File: /var/www/api.javaapp.co.uk/node_modules/@firebase/database/dist/src/api/Reference_impl.d.ts
/**
* @license
* Copyright 2020 Google LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import { Repo } from '../core/Repo';
import { Index } from '../core/snap/indexes/Index';
import { Node } from '../core/snap/Node';
import { Path } from '../core/util/Path';
import { Change } from '../core/view/Change';
import { CancelEvent, DataEvent, EventType } from '../core/view/Event';
import { CallbackContext, EventRegistration, QueryContext } from '../core/view/EventRegistration';
import { QueryParams } from '../core/view/QueryParams';
import { Database } from './Database';
import { OnDisconnect } from './OnDisconnect';
import { ListenOptions, Query as Query, DatabaseReference, Unsubscribe, ThenableReference } from './Reference';
/**
* @internal
*/
export declare class QueryImpl implements Query, QueryContext {
readonly _repo: Repo;
readonly _path: Path;
readonly _queryParams: QueryParams;
readonly _orderByCalled: boolean;
/**
* @hideconstructor
*/
constructor(_repo: Repo, _path: Path, _queryParams: QueryParams, _orderByCalled: boolean);
get key(): string | null;
get ref(): DatabaseReference;
get _queryIdentifier(): string;
/**
* An object representation of the query parameters used by this Query.
*/
get _queryObject(): object;
isEqual(other: QueryImpl | null): boolean;
toJSON(): string;
toString(): string;
}
/**
* @internal
*/
export declare class ReferenceImpl extends QueryImpl implements DatabaseReference {
/** @hideconstructor */
constructor(repo: Repo, path: Path);
get parent(): ReferenceImpl | null;
get root(): ReferenceImpl;
}
/**
* A `DataSnapshot` contains data from a Database location.
*
* Any time you read data from the Database, you receive the data as a
* `DataSnapshot`. A `DataSnapshot` is passed to the event callbacks you attach
* with `on()` or `once()`. You can extract the contents of the snapshot as a
* JavaScript object by calling the `val()` method. Alternatively, you can
* traverse into the snapshot by calling `child()` to return child snapshots
* (which you could then call `val()` on).
*
* A `DataSnapshot` is an efficiently generated, immutable copy of the data at
* a Database location. It cannot be modified and will never change (to modify
* data, you always call the `set()` method on a `Reference` directly).
*/
export declare class DataSnapshot {
readonly _node: Node;
/**
* The location of this DataSnapshot.
*/
readonly ref: DatabaseReference;
readonly _index: Index;
/**
* @param _node - A SnapshotNode to wrap.
* @param ref - The location this snapshot came from.
* @param _index - The iteration order for this snapshot
* @hideconstructor
*/
constructor(_node: Node,
/**
* The location of this DataSnapshot.
*/
ref: DatabaseReference, _index: Index);
/**
* Gets the priority value of the data in this `DataSnapshot`.
*
* Applications need not use priority but can order collections by
* ordinary properties (see
* {@link https://firebase.google.com/docs/database/web/lists-of-data#sorting_and_filtering_data |Sorting and filtering data}
* ).
*/
get priority(): string | number | null;
/**
* The key (last part of the path) of the location of this `DataSnapshot`.
*
* The last token in a Database location is considered its key. For example,
* "ada" is the key for the /users/ada/ node. Accessing the key on any
* `DataSnapshot` will return the key for the location that generated it.
* However, accessing the key on the root URL of a Database will return
* `null`.
*/
get key(): string | null;
/** Returns the number of child properties of this `DataSnapshot`. */
get size(): number;
/**
* Gets another `DataSnapshot` for the location at the specified relative path.
*
* Passing a relative path to the `child()` method of a DataSnapshot returns
* another `DataSnapshot` for the location at the specified relative path. The
* relative path can either be a simple child name (for example, "ada") or a
* deeper, slash-separated path (for example, "ada/name/first"). If the child
* location has no data, an empty `DataSnapshot` (that is, a `DataSnapshot`
* whose value is `null`) is returned.
*
* @param path - A relative path to the location of child data.
*/
child(path: string): DataSnapshot;
/**
* Returns true if this `DataSnapshot` contains any data. It is slightly more
* efficient than using `snapshot.val() !== null`.
*/
exists(): boolean;
/**
* Exports the entire contents of the DataSnapshot as a JavaScript object.
*
* The `exportVal()` method is similar to `val()`, except priority information
* is included (if available), making it suitable for backing up your data.
*
* @returns The DataSnapshot's contents as a JavaScript value (Object,
* Array, string, number, boolean, or `null`).
*/
exportVal(): any;
/**
* Enumerates the top-level children in the `IteratedDataSnapshot`.
*
* Because of the way JavaScript objects work, the ordering of data in the
* JavaScript object returned by `val()` is not guaranteed to match the
* ordering on the server nor the ordering of `onChildAdded()` events. That is
* where `forEach()` comes in handy. It guarantees the children of a
* `DataSnapshot` will be iterated in their query order.
*
* If no explicit `orderBy*()` method is used, results are returned
* ordered by key (unless priorities are used, in which case, results are
* returned by priority).
*
* @param action - A function that will be called for each child DataSnapshot.
* The callback can return true to cancel further enumeration.
* @returns true if enumeration was canceled due to your callback returning
* true.
*/
forEach(action: (child: IteratedDataSnapshot) => boolean | void): boolean;
/**
* Returns true if the specified child path has (non-null) data.
*
* @param path - A relative path to the location of a potential child.
* @returns `true` if data exists at the specified child path; else
* `false`.
*/
hasChild(path: string): boolean;
/**
* Returns whether or not the `DataSnapshot` has any non-`null` child
* properties.
*
* You can use `hasChildren()` to determine if a `DataSnapshot` has any
* children. If it does, you can enumerate them using `forEach()`. If it
* doesn't, then either this snapshot contains a primitive value (which can be
* retrieved with `val()`) or it is empty (in which case, `val()` will return
* `null`).
*
* @returns true if this snapshot has any children; else false.
*/
hasChildren(): boolean;
/**
* Returns a JSON-serializable representation of this object.
*/
toJSON(): object | null;
/**
* Extracts a JavaScript value from a `DataSnapshot`.
*
* Depending on the data in a `DataSnapshot`, the `val()` method may return a
* scalar type (string, number, or boolean), an array, or an object. It may
* also return null, indicating that the `DataSnapshot` is empty (contains no
* data).
*
* @returns The DataSnapshot's contents as a JavaScript value (Object,
* Array, string, number, boolean, or `null`).
*/
val(): any;
}
/**
* Represents a child snapshot of a `Reference` that is being iterated over. The key will never be undefined.
*/
export interface IteratedDataSnapshot extends DataSnapshot {
key: string;
}
/**
*
* Returns a `Reference` representing the location in the Database
* corresponding to the provided path. If no path is provided, the `Reference`
* will point to the root of the Database.
*
* @param db - The database instance to obtain a reference for.
* @param path - Optional path representing the location the returned
* `Reference` will point. If not provided, the returned `Reference` will
* point to the root of the Database.
* @returns If a path is provided, a `Reference`
* pointing to the provided path. Otherwise, a `Reference` pointing to the
* root of the Database.
*/
export declare function ref(db: Database, path?: string): DatabaseReference;
/**
* Returns a `Reference` representing the location in the Database
* corresponding to the provided Firebase URL.
*
* An exception is thrown if the URL is not a valid Firebase Database URL or it
* has a different domain than the current `Database` instance.
*
* Note that all query parameters (`orderBy`, `limitToLast`, etc.) are ignored
* and are not applied to the returned `Reference`.
*
* @param db - The database instance to obtain a reference for.
* @param url - The Firebase URL at which the returned `Reference` will
* point.
* @returns A `Reference` pointing to the provided
* Firebase URL.
*/
export declare function refFromURL(db: Database, url: string): DatabaseReference;
/**
* Gets a `Reference` for the location at the specified relative path.
*
* The relative path can either be a simple child name (for example, "ada") or
* a deeper slash-separated path (for example, "ada/name/first").
*
* @param parent - The parent location.
* @param path - A relative path from this location to the desired child
* location.
* @returns The specified child location.
*/
export declare function child(parent: DatabaseReference, path: string): DatabaseReference;
/**
* Returns an `OnDisconnect` object - see
* {@link https://firebase.google.com/docs/database/web/offline-capabilities | Enabling Offline Capabilities in JavaScript}
* for more information on how to use it.
*
* @param ref - The reference to add OnDisconnect triggers for.
*/
export declare function onDisconnect(ref: DatabaseReference): OnDisconnect;
export interface ThenableReferenceImpl extends ReferenceImpl, Pick<Promise<ReferenceImpl>, 'then' | 'catch'> {
}
/**
* Generates a new child location using a unique key and returns its
* `Reference`.
*
* This is the most common pattern for adding data to a collection of items.
*
* If you provide a value to `push()`, the value is written to the
* generated location. If you don't pass a value, nothing is written to the
* database and the child remains empty (but you can use the `Reference`
* elsewhere).
*
* The unique keys generated by `push()` are ordered by the current time, so the
* resulting list of items is chronologically sorted. The keys are also
* designed to be unguessable (they contain 72 random bits of entropy).
*
* See {@link https://firebase.google.com/docs/database/web/lists-of-data#append_to_a_list_of_data | Append to a list of data}.
* See {@link https://firebase.googleblog.com/2015/02/the-2120-ways-to-ensure-unique_68.html | The 2^120 Ways to Ensure Unique Identifiers}.
*
* @param parent - The parent location.
* @param value - Optional value to be written at the generated location.
* @returns Combined `Promise` and `Reference`; resolves when write is complete,
* but can be used immediately as the `Reference` to the child location.
*/
export declare function push(parent: DatabaseReference, value?: unknown): ThenableReference;
/**
* Removes the data at this Database location.
*
* Any data at child locations will also be deleted.
*
* The effect of the remove will be visible immediately and the corresponding
* event 'value' will be triggered. Synchronization of the remove to the
* Firebase servers will also be started, and the returned Promise will resolve
* when complete. If provided, the onComplete callback will be called
* asynchronously after synchronization has finished.
*
* @param ref - The location to remove.
* @returns Resolves when remove on server is complete.
*/
export declare function remove(ref: DatabaseReference): Promise<void>;
/**
* Writes data to this Database location.
*
* This will overwrite any data at this location and all child locations.
*
* The effect of the write will be visible immediately, and the corresponding
* events ("value", "child_added", etc.) will be triggered. Synchronization of
* the data to the Firebase servers will also be started, and the returned
* Promise will resolve when complete. If provided, the `onComplete` callback
* will be called asynchronously after synchronization has finished.
*
* Passing `null` for the new value is equivalent to calling `remove()`; namely,
* all data at this location and all child locations will be deleted.
*
* `set()` will remove any priority stored at this location, so if priority is
* meant to be preserved, you need to use `setWithPriority()` instead.
*
* Note that modifying data with `set()` will cancel any pending transactions
* at that location, so extreme care should be taken if mixing `set()` and
* `transaction()` to modify the same data.
*
* A single `set()` will generate a single "value" event at the location where
* the `set()` was performed.
*
* @param ref - The location to write to.
* @param value - The value to be written (string, number, boolean, object,
* array, or null).
* @returns Resolves when write to server is complete.
*/
export declare function set(ref: DatabaseReference, value: unknown): Promise<void>;
/**
* Sets a priority for the data at this Database location.
*
* Applications need not use priority but can order collections by
* ordinary properties (see
* {@link https://firebase.google.com/docs/database/web/lists-of-data#sorting_and_filtering_data | Sorting and filtering data}
* ).
*
* @param ref - The location to write to.
* @param priority - The priority to be written (string, number, or null).
* @returns Resolves when write to server is complete.
*/
export declare function setPriority(ref: DatabaseReference, priority: string | number | null): Promise<void>;
/**
* Writes data the Database location. Like `set()` but also specifies the
* priority for that data.
*
* Applications need not use priority but can order collections by
* ordinary properties (see
* {@link https://firebase.google.com/docs/database/web/lists-of-data#sorting_and_filtering_data | Sorting and filtering data}
* ).
*
* @param ref - The location to write to.
* @param value - The value to be written (string, number, boolean, object,
* array, or null).
* @param priority - The priority to be written (string, number, or null).
* @returns Resolves when write to server is complete.
*/
export declare function setWithPriority(ref: DatabaseReference, value: unknown, priority: string | number | null): Promise<void>;
/**
* Writes multiple values to the Database at once.
*
* The `values` argument contains multiple property-value pairs that will be
* written to the Database together. Each child property can either be a simple
* property (for example, "name") or a relative path (for example,
* "name/first") from the current location to the data to update.
*
* As opposed to the `set()` method, `update()` can be use to selectively update
* only the referenced properties at the current location (instead of replacing
* all the child properties at the current location).
*
* The effect of the write will be visible immediately, and the corresponding
* events ('value', 'child_added', etc.) will be triggered. Synchronization of
* the data to the Firebase servers will also be started, and the returned
* Promise will resolve when complete. If provided, the `onComplete` callback
* will be called asynchronously after synchronization has finished.
*
* A single `update()` will generate a single "value" event at the location
* where the `update()` was performed, regardless of how many children were
* modified.
*
* Note that modifying data with `update()` will cancel any pending
* transactions at that location, so extreme care should be taken if mixing
* `update()` and `transaction()` to modify the same data.
*
* Passing `null` to `update()` will remove the data at this location.
*
* See
* {@link https://firebase.googleblog.com/2015/09/introducing-multi-location-updates-and_86.html | Introducing multi-location updates and more}.
*
* @param ref - The location to write to.
* @param values - Object containing multiple values.
* @returns Resolves when update on server is complete.
*/
export declare function update(ref: DatabaseReference, values: object): Promise<void>;
/**
* Gets the most up-to-date result for this query.
*
* @param query - The query to run.
* @returns A `Promise` which resolves to the resulting DataSnapshot if a value is
* available, or rejects if the client is unable to return a value (e.g., if the
* server is unreachable and there is nothing cached).
*/
export declare function get(query: Query): Promise<DataSnapshot>;
/**
* Represents registration for 'value' events.
*/
export declare class ValueEventRegistration implements EventRegistration {
private callbackContext;
constructor(callbackContext: CallbackContext);
respondsTo(eventType: string): boolean;
createEvent(change: Change, query: QueryContext): DataEvent;
getEventRunner(eventData: CancelEvent | DataEvent): () => void;
createCancelEvent(error: Error, path: Path): CancelEvent | null;
matches(other: EventRegistration): boolean;
hasAnyCallback(): boolean;
}
/**
* Represents the registration of a child_x event.
*/
export declare class ChildEventRegistration implements EventRegistration {
private eventType;
private callbackContext;
constructor(eventType: string, callbackContext: CallbackContext | null);
respondsTo(eventType: string): boolean;
createCancelEvent(error: Error, path: Path): CancelEvent | null;
createEvent(change: Change, query: QueryContext): DataEvent;
getEventRunner(eventData: CancelEvent | DataEvent): () => void;
matches(other: EventRegistration): boolean;
hasAnyCallback(): boolean;
}
/**
* Listens for data changes at a particular location.
*
* This is the primary way to read data from a Database. Your callback
* will be triggered for the initial data and again whenever the data changes.
* Invoke the returned unsubscribe callback to stop receiving updates. See
* {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
* for more details.
*
* An `onValue` event will trigger once with the initial data stored at this
* location, and then trigger again each time the data changes. The
* `DataSnapshot` passed to the callback will be for the location at which
* `on()` was called. It won't trigger until the entire contents has been
* synchronized. If the location has no data, it will be triggered with an empty
* `DataSnapshot` (`val()` will return `null`).
*
* @param query - The query to run.
* @param callback - A callback that fires when the specified event occurs. The
* callback will be passed a DataSnapshot.
* @param cancelCallback - An optional callback that will be notified if your
* event subscription is ever canceled because your client does not have
* permission to read this data (or it had permission but has now lost it).
* This callback will be passed an `Error` object indicating why the failure
* occurred.
* @returns A function that can be invoked to remove the listener.
*/
export declare function onValue(query: Query, callback: (snapshot: DataSnapshot) => unknown, cancelCallback?: (error: Error) => unknown): Unsubscribe;
/**
* Listens for data changes at a particular location.
*
* This is the primary way to read data from a Database. Your callback
* will be triggered for the initial data and again whenever the data changes.
* Invoke the returned unsubscribe callback to stop receiving updates. See
* {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
* for more details.
*
* An `onValue` event will trigger once with the initial data stored at this
* location, and then trigger again each time the data changes. The
* `DataSnapshot` passed to the callback will be for the location at which
* `on()` was called. It won't trigger until the entire contents has been
* synchronized. If the location has no data, it will be triggered with an empty
* `DataSnapshot` (`val()` will return `null`).
*
* @param query - The query to run.
* @param callback - A callback that fires when the specified event occurs. The
* callback will be passed a DataSnapshot.
* @param options - An object that can be used to configure `onlyOnce`, which
* then removes the listener after its first invocation.
* @returns A function that can be invoked to remove the listener.
*/
export declare function onValue(query: Query, callback: (snapshot: DataSnapshot) => unknown, options: ListenOptions): Unsubscribe;
/**
* Listens for data changes at a particular location.
*
* This is the primary way to read data from a Database. Your callback
* will be triggered for the initial data and again whenever the data changes.
* Invoke the returned unsubscribe callback to stop receiving updates. See
* {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
* for more details.
*
* An `onValue` event will trigger once with the initial data stored at this
* location, and then trigger again each time the data changes. The
* `DataSnapshot` passed to the callback will be for the location at which
* `on()` was called. It won't trigger until the entire contents has been
* synchronized. If the location has no data, it will be triggered with an empty
* `DataSnapshot` (`val()` will return `null`).
*
* @param query - The query to run.
* @param callback - A callback that fires when the specified event occurs. The
* callback will be passed a DataSnapshot.
* @param cancelCallback - An optional callback that will be notified if your
* event subscription is ever canceled because your client does not have
* permission to read this data (or it had permission but has now lost it).
* This callback will be passed an `Error` object indicating why the failure
* occurred.
* @param options - An object that can be used to configure `onlyOnce`, which
* then removes the listener after its first invocation.
* @returns A function that can be invoked to remove the listener.
*/
export declare function onValue(query: Query, callback: (snapshot: DataSnapshot) => unknown, cancelCallback: (error: Error) => unknown, options: ListenOptions): Unsubscribe;
/**
* Listens for data changes at a particular location.
*
* This is the primary way to read data from a Database. Your callback
* will be triggered for the initial data and again whenever the data changes.
* Invoke the returned unsubscribe callback to stop receiving updates. See
* {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
* for more details.
*
* An `onChildAdded` event will be triggered once for each initial child at this
* location, and it will be triggered again every time a new child is added. The
* `DataSnapshot` passed into the callback will reflect the data for the
* relevant child. For ordering purposes, it is passed a second argument which
* is a string containing the key of the previous sibling child by sort order,
* or `null` if it is the first child.
*
* @param query - The query to run.
* @param callback - A callback that fires when the specified event occurs.
* The callback will be passed a DataSnapshot and a string containing the key of
* the previous child, by sort order, or `null` if it is the first child.
* @param cancelCallback - An optional callback that will be notified if your
* event subscription is ever canceled because your client does not have
* permission to read this data (or it had permission but has now lost it).
* This callback will be passed an `Error` object indicating why the failure
* occurred.
* @returns A function that can be invoked to remove the listener.
*/
export declare function onChildAdded(query: Query, callback: (snapshot: DataSnapshot, previousChildName?: string | null) => unknown, cancelCallback?: (error: Error) => unknown): Unsubscribe;
/**
* Listens for data changes at a particular location.
*
* This is the primary way to read data from a Database. Your callback
* will be triggered for the initial data and again whenever the data changes.
* Invoke the returned unsubscribe callback to stop receiving updates. See
* {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
* for more details.
*
* An `onChildAdded` event will be triggered once for each initial child at this
* location, and it will be triggered again every time a new child is added. The
* `DataSnapshot` passed into the callback will reflect the data for the
* relevant child. For ordering purposes, it is passed a second argument which
* is a string containing the key of the previous sibling child by sort order,
* or `null` if it is the first child.
*
* @param query - The query to run.
* @param callback - A callback that fires when the specified event occurs.
* The callback will be passed a DataSnapshot and a string containing the key of
* the previous child, by sort order, or `null` if it is the first child.
* @param options - An object that can be used to configure `onlyOnce`, which
* then removes the listener after its first invocation.
* @returns A function that can be invoked to remove the listener.
*/
export declare function onChildAdded(query: Query, callback: (snapshot: DataSnapshot, previousChildName: string | null) => unknown, options: ListenOptions): Unsubscribe;
/**
* Listens for data changes at a particular location.
*
* This is the primary way to read data from a Database. Your callback
* will be triggered for the initial data and again whenever the data changes.
* Invoke the returned unsubscribe callback to stop receiving updates. See
* {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
* for more details.
*
* An `onChildAdded` event will be triggered once for each initial child at this
* location, and it will be triggered again every time a new child is added. The
* `DataSnapshot` passed into the callback will reflect the data for the
* relevant child. For ordering purposes, it is passed a second argument which
* is a string containing the key of the previous sibling child by sort order,
* or `null` if it is the first child.
*
* @param query - The query to run.
* @param callback - A callback that fires when the specified event occurs.
* The callback will be passed a DataSnapshot and a string containing the key of
* the previous child, by sort order, or `null` if it is the first child.
* @param cancelCallback - An optional callback that will be notified if your
* event subscription is ever canceled because your client does not have
* permission to read this data (or it had permission but has now lost it).
* This callback will be passed an `Error` object indicating why the failure
* occurred.
* @param options - An object that can be used to configure `onlyOnce`, which
* then removes the listener after its first invocation.
* @returns A function that can be invoked to remove the listener.
*/
export declare function onChildAdded(query: Query, callback: (snapshot: DataSnapshot, previousChildName: string | null) => unknown, cancelCallback: (error: Error) => unknown, options: ListenOptions): Unsubscribe;
/**
* Listens for data changes at a particular location.
*
* This is the primary way to read data from a Database. Your callback
* will be triggered for the initial data and again whenever the data changes.
* Invoke the returned unsubscribe callback to stop receiving updates. See
* {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
* for more details.
*
* An `onChildChanged` event will be triggered when the data stored in a child
* (or any of its descendants) changes. Note that a single `child_changed` event
* may represent multiple changes to the child. The `DataSnapshot` passed to the
* callback will contain the new child contents. For ordering purposes, the
* callback is also passed a second argument which is a string containing the
* key of the previous sibling child by sort order, or `null` if it is the first
* child.
*
* @param query - The query to run.
* @param callback - A callback that fires when the specified event occurs.
* The callback will be passed a DataSnapshot and a string containing the key of
* the previous child, by sort order, or `null` if it is the first child.
* @param cancelCallback - An optional callback that will be notified if your
* event subscription is ever canceled because your client does not have
* permission to read this data (or it had permission but has now lost it).
* This callback will be passed an `Error` object indicating why the failure
* occurred.
* @returns A function that can be invoked to remove the listener.
*/
export declare function onChildChanged(query: Query, callback: (snapshot: DataSnapshot, previousChildName: string | null) => unknown, cancelCallback?: (error: Error) => unknown): Unsubscribe;
/**
* Listens for data changes at a particular location.
*
* This is the primary way to read data from a Database. Your callback
* will be triggered for the initial data and again whenever the data changes.
* Invoke the returned unsubscribe callback to stop receiving updates. See
* {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
* for more details.
*
* An `onChildChanged` event will be triggered when the data stored in a child
* (or any of its descendants) changes. Note that a single `child_changed` event
* may represent multiple changes to the child. The `DataSnapshot` passed to the
* callback will contain the new child contents. For ordering purposes, the
* callback is also passed a second argument which is a string containing the
* key of the previous sibling child by sort order, or `null` if it is the first
* child.
*
* @param query - The query to run.
* @param callback - A callback that fires when the specified event occurs.
* The callback will be passed a DataSnapshot and a string containing the key of
* the previous child, by sort order, or `null` if it is the first child.
* @param options - An object that can be used to configure `onlyOnce`, which
* then removes the listener after its first invocation.
* @returns A function that can be invoked to remove the listener.
*/
export declare function onChildChanged(query: Query, callback: (snapshot: DataSnapshot, previousChildName: string | null) => unknown, options: ListenOptions): Unsubscribe;
/**
* Listens for data changes at a particular location.
*
* This is the primary way to read data from a Database. Your callback
* will be triggered for the initial data and again whenever the data changes.
* Invoke the returned unsubscribe callback to stop receiving updates. See
* {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
* for more details.
*
* An `onChildChanged` event will be triggered when the data stored in a child
* (or any of its descendants) changes. Note that a single `child_changed` event
* may represent multiple changes to the child. The `DataSnapshot` passed to the
* callback will contain the new child contents. For ordering purposes, the
* callback is also passed a second argument which is a string containing the
* key of the previous sibling child by sort order, or `null` if it is the first
* child.
*
* @param query - The query to run.
* @param callback - A callback that fires when the specified event occurs.
* The callback will be passed a DataSnapshot and a string containing the key of
* the previous child, by sort order, or `null` if it is the first child.
* @param cancelCallback - An optional callback that will be notified if your
* event subscription is ever canceled because your client does not have
* permission to read this data (or it had permission but has now lost it).
* This callback will be passed an `Error` object indicating why the failure
* occurred.
* @param options - An object that can be used to configure `onlyOnce`, which
* then removes the listener after its first invocation.
* @returns A function that can be invoked to remove the listener.
*/
export declare function onChildChanged(query: Query, callback: (snapshot: DataSnapshot, previousChildName: string | null) => unknown, cancelCallback: (error: Error) => unknown, options: ListenOptions): Unsubscribe;
/**
* Listens for data changes at a particular location.
*
* This is the primary way to read data from a Database. Your callback
* will be triggered for the initial data and again whenever the data changes.
* Invoke the returned unsubscribe callback to stop receiving updates. See
* {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
* for more details.
*
* An `onChildMoved` event will be triggered when a child's sort order changes
* such that its position relative to its siblings changes. The `DataSnapshot`
* passed to the callback will be for the data of the child that has moved. It
* is also passed a second argument which is a string containing the key of the
* previous sibling child by sort order, or `null` if it is the first child.
*
* @param query - The query to run.
* @param callback - A callback that fires when the specified event occurs.
* The callback will be passed a DataSnapshot and a string containing the key of
* the previous child, by sort order, or `null` if it is the first child.
* @param cancelCallback - An optional callback that will be notified if your
* event subscription is ever canceled because your client does not have
* permission to read this data (or it had permission but has now lost it).
* This callback will be passed an `Error` object indicating why the failure
* occurred.
* @returns A function that can be invoked to remove the listener.
*/
export declare function onChildMoved(query: Query, callback: (snapshot: DataSnapshot, previousChildName: string | null) => unknown, cancelCallback?: (error: Error) => unknown): Unsubscribe;
/**
* Listens for data changes at a particular location.
*
* This is the primary way to read data from a Database. Your callback
* will be triggered for the initial data and again whenever the data changes.
* Invoke the returned unsubscribe callback to stop receiving updates. See
* {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
* for more details.
*
* An `onChildMoved` event will be triggered when a child's sort order changes
* such that its position relative to its siblings changes. The `DataSnapshot`
* passed to the callback will be for the data of the child that has moved. It
* is also passed a second argument which is a string containing the key of the
* previous sibling child by sort order, or `null` if it is the first child.
*
* @param query - The query to run.
* @param callback - A callback that fires when the specified event occurs.
* The callback will be passed a DataSnapshot and a string containing the key of
* the previous child, by sort order, or `null` if it is the first child.
* @param options - An object that can be used to configure `onlyOnce`, which
* then removes the listener after its first invocation.
* @returns A function that can be invoked to remove the listener.
*/
export declare function onChildMoved(query: Query, callback: (snapshot: DataSnapshot, previousChildName: string | null) => unknown, options: ListenOptions): Unsubscribe;
/**
* Listens for data changes at a particular location.
*
* This is the primary way to read data from a Database. Your callback
* will be triggered for the initial data and again whenever the data changes.
* Invoke the returned unsubscribe callback to stop receiving updates. See
* {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
* for more details.
*
* An `onChildMoved` event will be triggered when a child's sort order changes
* such that its position relative to its siblings changes. The `DataSnapshot`
* passed to the callback will be for the data of the child that has moved. It
* is also passed a second argument which is a string containing the key of the
* previous sibling child by sort order, or `null` if it is the first child.
*
* @param query - The query to run.
* @param callback - A callback that fires when the specified event occurs.
* The callback will be passed a DataSnapshot and a string containing the key of
* the previous child, by sort order, or `null` if it is the first child.
* @param cancelCallback - An optional callback that will be notified if your
* event subscription is ever canceled because your client does not have
* permission to read this data (or it had permission but has now lost it).
* This callback will be passed an `Error` object indicating why the failure
* occurred.
* @param options - An object that can be used to configure `onlyOnce`, which
* then removes the listener after its first invocation.
* @returns A function that can be invoked to remove the listener.
*/
export declare function onChildMoved(query: Query, callback: (snapshot: DataSnapshot, previousChildName: string | null) => unknown, cancelCallback: (error: Error) => unknown, options: ListenOptions): Unsubscribe;
/**
* Listens for data changes at a particular location.
*
* This is the primary way to read data from a Database. Your callback
* will be triggered for the initial data and again whenever the data changes.
* Invoke the returned unsubscribe callback to stop receiving updates. See
* {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
* for more details.
*
* An `onChildRemoved` event will be triggered once every time a child is
* removed. The `DataSnapshot` passed into the callback will be the old data for
* the child that was removed. A child will get removed when either:
*
* - a client explicitly calls `remove()` on that child or one of its ancestors
* - a client calls `set(null)` on that child or one of its ancestors
* - that child has all of its children removed
* - there is a query in effect which now filters out the child (because it's
* sort order changed or the max limit was hit)
*
* @param query - The query to run.
* @param callback - A callback that fires when the specified event occurs.
* The callback will be passed a DataSnapshot and a string containing the key of
* the previous child, by sort order, or `null` if it is the first child.
* @param cancelCallback - An optional callback that will be notified if your
* event subscription is ever canceled because your client does not have
* permission to read this data (or it had permission but has now lost it).
* This callback will be passed an `Error` object indicating why the failure
* occurred.
* @returns A function that can be invoked to remove the listener.
*/
export declare function onChildRemoved(query: Query, callback: (snapshot: DataSnapshot) => unknown, cancelCallback?: (error: Error) => unknown): Unsubscribe;
/**
* Listens for data changes at a particular location.
*
* This is the primary way to read data from a Database. Your callback
* will be triggered for the initial data and again whenever the data changes.
* Invoke the returned unsubscribe callback to stop receiving updates. See
* {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
* for more details.
*
* An `onChildRemoved` event will be triggered once every time a child is
* removed. The `DataSnapshot` passed into the callback will be the old data for
* the child that was removed. A child will get removed when either:
*
* - a client explicitly calls `remove()` on that child or one of its ancestors
* - a client calls `set(null)` on that child or one of its ancestors
* - that child has all of its children removed
* - there is a query in effect which now filters out the child (because it's
* sort order changed or the max limit was hit)
*
* @param query - The query to run.
* @param callback - A callback that fires when the specified event occurs.
* The callback will be passed a DataSnapshot and a string containing the key of
* the previous child, by sort order, or `null` if it is the first child.
* @param options - An object that can be used to configure `onlyOnce`, which
* then removes the listener after its first invocation.
* @returns A function that can be invoked to remove the listener.
*/
export declare function onChildRemoved(query: Query, callback: (snapshot: DataSnapshot) => unknown, options: ListenOptions): Unsubscribe;
/**
* Listens for data changes at a particular location.
*
* This is the primary way to read data from a Database. Your callback
* will be triggered for the initial data and again whenever the data changes.
* Invoke the returned unsubscribe callback to stop receiving updates. See
* {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
* for more details.
*
* An `onChildRemoved` event will be triggered once every time a child is
* removed. The `DataSnapshot` passed into the callback will be the old data for
* the child that was removed. A child will get removed when either:
*
* - a client explicitly calls `remove()` on that child or one of its ancestors
* - a client calls `set(null)` on that child or one of its ancestors
* - that child has all of its children removed
* - there is a query in effect which now filters out the child (because it's
* sort order changed or the max limit was hit)
*
* @param query - The query to run.
* @param callback - A callback that fires when the specified event occurs.
* The callback will be passed a DataSnapshot and a string containing the key of
* the previous child, by sort order, or `null` if it is the first child.
* @param cancelCallback - An optional callback that will be notified if your
* event subscription is ever canceled because your client does not have
* permission to read this data (or it had permission but has now lost it).
* This callback will be passed an `Error` object indicating why the failure
* occurred.
* @param options - An object that can be used to configure `onlyOnce`, which
* then removes the listener after its first invocation.
* @returns A function that can be invoked to remove the listener.
*/
export declare function onChildRemoved(query: Query, callback: (snapshot: DataSnapshot) => unknown, cancelCallback: (error: Error) => unknown, options: ListenOptions): Unsubscribe;
export { EventType };
/**
* Detaches a callback previously attached with the corresponding `on*()` (`onValue`, `onChildAdded`) listener.
* Note: This is not the recommended way to remove a listener. Instead, please use the returned callback function from
* the respective `on*` callbacks.
*
* Detach a callback previously attached with `on*()`. Calling `off()` on a parent listener
* will not automatically remove listeners registered on child nodes, `off()`
* must also be called on any child listeners to remove the callback.
*
* If a callback is not specified, all callbacks for the specified eventType
* will be removed. Similarly, if no eventType is specified, all callbacks
* for the `Reference` will be removed.
*
* Individual listeners can also be removed by invoking their unsubscribe
* callbacks.
*
* @param query - The query that the listener was registered with.
* @param eventType - One of the following strings: "value", "child_added",
* "child_changed", "child_removed", or "child_moved." If omitted, all callbacks
* for the `Reference` will be removed.
* @param callback - The callback function that was passed to `on()` or
* `undefined` to remove all callbacks.
*/
export declare function off(query: Query, eventType?: EventType, callback?: (snapshot: DataSnapshot, previousChildName?: string | null) => unknown): void;
/** Describes the different query constraints available in this SDK. */
export declare type QueryConstraintType = 'endAt' | 'endBefore' | 'startAt' | 'startAfter' | 'limitToFirst' | 'limitToLast' | 'orderByChild' | 'orderByKey' | 'orderByPriority' | 'orderByValue' | 'equalTo';
/**
* A `QueryConstraint` is used to narrow the set of documents returned by a
* Database query. `QueryConstraint`s are created by invoking {@link endAt},
* {@link endBefore}, {@link startAt}, {@link startAfter}, {@link
* limitToFirst}, {@link limitToLast}, {@link orderByChild},
* {@link orderByChild}, {@link orderByKey} , {@link orderByPriority} ,
* {@link orderByValue} or {@link equalTo} and
* can then be passed to {@link query} to create a new query instance that
* also contains this `QueryConstraint`.
*/
export declare abstract class QueryConstraint {
/** The type of this query constraints */
abstract readonly type: QueryConstraintType;
/**
* Takes the provided `Query` and returns a copy of the `Query` with this
* `QueryConstraint` applied.
*/
abstract _apply<T>(query: QueryImpl): QueryImpl;
}
/**
* Creates a `QueryConstraint` with the specified ending point.
*
* Using `startAt()`, `startAfter()`, `endBefore()`, `endAt()` and `equalTo()`
* allows you to choose arbitrary starting and ending points for your queries.
*
* The ending point is inclusive, so children with exactly the specified value
* will be included in the query. The optional key argument can be used to
* further limit the range of the query. If it is specified, then children that
* have exactly the specified value must also have a key name less than or equal
* to the specified key.
*
* You can read more about `endAt()` in
* {@link https://firebase.google.com/docs/database/web/lists-of-data#filtering_data | Filtering data}.
*
* @param value - The value to end at. The argument type depends on which
* `orderBy*()` function was used in this query. Specify a value that matches
* the `orderBy*()` type. When used in combination with `orderByKey()`, the
* value must be a string.
* @param key - The child key to end at, among the children with the previously
* specified priority. This argument is only allowed if ordering by child,
* value, or priority.
*/
export declare function endAt(value: number | string | boolean | null, key?: string): QueryConstraint;
/**
* Creates a `QueryConstraint` with the specified ending point (exclusive).
*
* Using `startAt()`, `startAfter()`, `endBefore()`, `endAt()` and `equalTo()`
* allows you to choose arbitrary starting and ending points for your queries.
*
* The ending point is exclusive. If only a value is provided, children
* with a value less than the specified value will be included in the query.
* If a key is specified, then children must have a value less than or equal
* to the specified value and a key name less than the specified key.
*
* @param value - The value to end before. The argument type depends on which
* `orderBy*()` function was used in this query. Specify a value that matches
* the `orderBy*()` type. When used in combination with `orderByKey()`, the
* value must be a string.
* @param key - The child key to end before, among the children with the
* previously specified priority. This argument is only allowed if ordering by
* child, value, or priority.
*/
export declare function endBefore(value: number | string | boolean | null, key?: string): QueryConstraint;
/**
* Creates a `QueryConstraint` with the specified starting point.
*
* Using `startAt()`, `startAfter()`, `endBefore()`, `endAt()` and `equalTo()`
* allows you to choose arbitrary starting and ending points for your queries.
*
* The starting point is inclusive, so children with exactly the specified value
* will be included in the query. The optional key argument can be used to
* further limit the range of the query. If it is specified, then children that
* have exactly the specified value must also have a key name greater than or
* equal to the specified key.
*
* You can read more about `startAt()` in
* {@link https://firebase.google.com/docs/database/web/lists-of-data#filtering_data | Filtering data}.
*
* @param value - The value to start at. The argument type depends on which
* `orderBy*()` function was used in this query. Specify a value that matches
* the `orderBy*()` type. When used in combination with `orderByKey()`, the
* value must be a string.
* @param key - The child key to start at. This argument is only allowed if
* ordering by child, value, or priority.
*/
export declare function startAt(value?: number | string | boolean | null, key?: string): QueryConstraint;
/**
* Creates a `QueryConstraint` with the specified starting point (exclusive).
*
* Using `startAt()`, `startAfter()`, `endBefore()`, `endAt()` and `equalTo()`
* allows you to choose arbitrary starting and ending points for your queries.
*
* The starting point is exclusive. If only a value is provided, children
* with a value greater than the specified value will be included in the query.
* If a key is specified, then children must have a value greater than or equal
* to the specified value and a a key name greater than the specified key.
*
* @param value - The value to start after. The argument type depends on which
* `orderBy*()` function was used in this query. Specify a value that matches
* the `orderBy*()` type. When used in combination with `orderByKey()`, the
* value must be a string.
* @param key - The child key to start after. This argument is only allowed if
* ordering by child, value, or priority.
*/
export declare function startAfter(value: number | string | boolean | null, key?: string): QueryConstraint;
/**
* Creates a new `QueryConstraint` that if limited to the first specific number
* of children.
*
* The `limitToFirst()` method is used to set a maximum number of children to be
* synced for a given callback. If we set a limit of 100, we will initially only
* receive up to 100 `child_added` events. If we have fewer than 100 messages
* stored in our Database, a `child_added` event will fire for each message.
* However, if we have over 100 messages, we will only receive a `child_added`
* event for the first 100 ordered messages. As items change, we will receive
* `child_removed` events for each item that drops out of the active list so
* that the total number stays at 100.
*
* You can read more about `limitToFirst()` in
* {@link https://firebase.google.com/docs/database/web/lists-of-data#filtering_data | Filtering data}.
*
* @param limit - The maximum number of nodes to include in this query.
*/
export declare function limitToFirst(limit: number): QueryConstraint;
/**
* Creates a new `QueryConstraint` that is limited to return only the last
* specified number of children.
*
* The `limitToLast()` method is used to set a maximum number of children to be
* synced for a given callback. If we set a limit of 100, we will initially only
* receive up to 100 `child_added` events. If we have fewer than 100 messages
* stored in our Database, a `child_added` event will fire for each message.
* However, if we have over 100 messages, we will only receive a `child_added`
* event for the last 100 ordered messages. As items change, we will receive
* `child_removed` events for each item that drops out of the active list so
* that the total number stays at 100.
*
* You can read more about `limitToLast()` in
* {@link https://firebase.google.com/docs/database/web/lists-of-data#filtering_data | Filtering data}.
*
* @param limit - The maximum number of nodes to include in this query.
*/
export declare function limitToLast(limit: number): QueryConstraint;
/**
* Creates a new `QueryConstraint` that orders by the specified child key.
*
* Queries can only order by one key at a time. Calling `orderByChild()`
* multiple times on the same query is an error.
*
* Firebase queries allow you to order your data by any child key on the fly.
* However, if you know in advance what your indexes will be, you can define
* them via the .indexOn rule in your Security Rules for better performance. See
* the{@link https://firebase.google.com/docs/database/security/indexing-data}
* rule for more information.
*
* You can read more about `orderByChild()` in
* {@link https://firebase.google.com/docs/database/web/lists-of-data#sort_data | Sort data}.
*
* @param path - The path to order by.
*/
export declare function orderByChild(path: string): QueryConstraint;
/**
* Creates a new `QueryConstraint` that orders by the key.
*
* Sorts the results of a query by their (ascending) key values.
*
* You can read more about `orderByKey()` in
* {@link https://firebase.google.com/docs/database/web/lists-of-data#sort_data | Sort data}.
*/
export declare function orderByKey(): QueryConstraint;
/**
* Creates a new `QueryConstraint` that orders by priority.
*
* Applications need not use priority but can order collections by
* ordinary properties (see
* {@link https://firebase.google.com/docs/database/web/lists-of-data#sort_data | Sort data}
* for alternatives to priority.
*/
export declare function orderByPriority(): QueryConstraint;
/**
* Creates a new `QueryConstraint` that orders by value.
*
* If the children of a query are all scalar values (string, number, or
* boolean), you can order the results by their (ascending) values.
*
* You can read more about `orderByValue()` in
* {@link https://firebase.google.com/docs/database/web/lists-of-data#sort_data | Sort data}.
*/
export declare function orderByValue(): QueryConstraint;
/**
* Creates a `QueryConstraint` that includes children that match the specified
* value.
*
* Using `startAt()`, `startAfter()`, `endBefore()`, `endAt()` and `equalTo()`
* allows you to choose arbitrary starting and ending points for your queries.
*
* The optional key argument can be used to further limit the range of the
* query. If it is specified, then children that have exactly the specified
* value must also have exactly the specified key as their key name. This can be
* used to filter result sets with many matches for the same value.
*
* You can read more about `equalTo()` in
* {@link https://firebase.google.com/docs/database/web/lists-of-data#filtering_data | Filtering data}.
*
* @param value - The value to match for. The argument type depends on which
* `orderBy*()` function was used in this query. Specify a value that matches
* the `orderBy*()` type. When used in combination with `orderByKey()`, the
* value must be a string.
* @param key - The child key to start at, among the children with the
* previously specified priority. This argument is only allowed if ordering by
* child, value, or priority.
*/
export declare function equalTo(value: number | string | boolean | null, key?: string): QueryConstraint;
/**
* Creates a new immutable instance of `Query` that is extended to also include
* additional query constraints.
*
* @param query - The Query instance to use as a base for the new constraints.
* @param queryConstraints - The list of `QueryConstraint`s to apply.
* @throws if any of the provided query constraints cannot be combined with the
* existing or new constraints.
*/
export declare function query(query: Query, ...queryConstraints: QueryConstraint[]): Query;