/
snapshot.ts
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/
snapshot.ts
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/**
* @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 { newQueryComparator } from '../core/query';
import { ChangeType, ViewSnapshot } from '../core/view_snapshot';
import { FieldPath } from '../lite-api/field_path';
import {
DocumentData,
PartialWithFieldValue,
Query,
queryEqual,
SetOptions,
WithFieldValue
} from '../lite-api/reference';
import {
DocumentSnapshot as LiteDocumentSnapshot,
fieldPathFromArgument,
FirestoreDataConverter as LiteFirestoreDataConverter
} from '../lite-api/snapshot';
import { UntypedFirestoreDataConverter } from '../lite-api/user_data_reader';
import { AbstractUserDataWriter } from '../lite-api/user_data_writer';
import { Document } from '../model/document';
import { DocumentKey } from '../model/document_key';
import { debugAssert, fail } from '../util/assert';
import { Code, FirestoreError } from '../util/error';
import { Firestore } from './database';
import { SnapshotListenOptions } from './reference_impl';
/**
* Converter used by `withConverter()` to transform user objects of type `T`
* into Firestore data.
*
* Using the converter allows you to specify generic type arguments when
* storing and retrieving objects from Firestore.
*
* @example
* ```typescript
* class Post {
* constructor(readonly title: string, readonly author: string) {}
*
* toString(): string {
* return this.title + ', by ' + this.author;
* }
* }
*
* const postConverter = {
* toFirestore(post: WithFieldValue<Post>): DocumentData {
* return {title: post.title, author: post.author};
* },
* fromFirestore(
* snapshot: QueryDocumentSnapshot,
* options: SnapshotOptions
* ): Post {
* const data = snapshot.data(options)!;
* return new Post(data.title, data.author);
* }
* };
*
* const postSnap = await firebase.firestore()
* .collection('posts')
* .withConverter(postConverter)
* .doc().get();
* const post = postSnap.data();
* if (post !== undefined) {
* post.title; // string
* post.toString(); // Should be defined
* post.someNonExistentProperty; // TS error
* }
* ```
*/
export interface FirestoreDataConverter<T>
extends LiteFirestoreDataConverter<T> {
/**
* Called by the Firestore SDK to convert a custom model object of type `T`
* into a plain JavaScript object (suitable for writing directly to the
* Firestore database). To use `set()` with `merge` and `mergeFields`,
* `toFirestore()` must be defined with `PartialWithFieldValue<T>`.
*
* The `WithFieldValue<T>` type extends `T` to also allow FieldValues such as
* {@link (deleteField:1)} to be used as property values.
*/
toFirestore(modelObject: WithFieldValue<T>): DocumentData;
/**
* Called by the Firestore SDK to convert a custom model object of type `T`
* into a plain JavaScript object (suitable for writing directly to the
* Firestore database). Used with {@link (setDoc:1)}, {@link (WriteBatch.set:1)}
* and {@link (Transaction.set:1)} with `merge:true` or `mergeFields`.
*
* The `PartialWithFieldValue<T>` type extends `Partial<T>` to allow
* FieldValues such as {@link (arrayUnion:1)} to be used as property values.
* It also supports nested `Partial` by allowing nested fields to be
* omitted.
*/
toFirestore(
modelObject: PartialWithFieldValue<T>,
options: SetOptions
): DocumentData;
/**
* Called by the Firestore SDK to convert Firestore data into an object of
* type T. You can access your data by calling: `snapshot.data(options)`.
*
* @param snapshot - A `QueryDocumentSnapshot` containing your data and metadata.
* @param options - The `SnapshotOptions` from the initial call to `data()`.
*/
fromFirestore(
snapshot: QueryDocumentSnapshot<DocumentData>,
options?: SnapshotOptions
): T;
}
/**
* Options that configure how data is retrieved from a `DocumentSnapshot` (for
* example the desired behavior for server timestamps that have not yet been set
* to their final value).
*/
export interface SnapshotOptions {
/**
* If set, controls the return value for server timestamps that have not yet
* been set to their final value.
*
* By specifying 'estimate', pending server timestamps return an estimate
* based on the local clock. This estimate will differ from the final value
* and cause these values to change once the server result becomes available.
*
* By specifying 'previous', pending timestamps will be ignored and return
* their previous value instead.
*
* If omitted or set to 'none', `null` will be returned by default until the
* server value becomes available.
*/
readonly serverTimestamps?: 'estimate' | 'previous' | 'none';
}
/**
* Metadata about a snapshot, describing the state of the snapshot.
*/
export class SnapshotMetadata {
/**
* True if the snapshot contains the result of local writes (for example
* `set()` or `update()` calls) that have not yet been committed to the
* backend. If your listener has opted into metadata updates (via
* `SnapshotListenOptions`) you will receive another snapshot with
* `hasPendingWrites` equal to false once the writes have been committed to
* the backend.
*/
readonly hasPendingWrites: boolean;
/**
* True if the snapshot was created from cached data rather than guaranteed
* up-to-date server data. If your listener has opted into metadata updates
* (via `SnapshotListenOptions`) you will receive another snapshot with
* `fromCache` set to false once the client has received up-to-date data from
* the backend.
*/
readonly fromCache: boolean;
/** @hideconstructor */
constructor(hasPendingWrites: boolean, fromCache: boolean) {
this.hasPendingWrites = hasPendingWrites;
this.fromCache = fromCache;
}
/**
* Returns true if this `SnapshotMetadata` is equal to the provided one.
*
* @param other - The `SnapshotMetadata` to compare against.
* @returns true if this `SnapshotMetadata` is equal to the provided one.
*/
isEqual(other: SnapshotMetadata): boolean {
return (
this.hasPendingWrites === other.hasPendingWrites &&
this.fromCache === other.fromCache
);
}
}
/**
* The type of a `DocumentChange` may be 'added', 'removed', or 'modified'.
*/
export type DocumentChangeType = 'added' | 'removed' | 'modified';
/**
* A `DocumentChange` represents a change to the documents matching a query.
* It contains the document affected and the type of change that occurred.
*/
export interface DocumentChange<T = DocumentData> {
/** The type of change ('added', 'modified', or 'removed'). */
readonly type: DocumentChangeType;
/** The document affected by this change. */
readonly doc: QueryDocumentSnapshot<T>;
/**
* The index of the changed document in the result set immediately prior to
* this `DocumentChange` (i.e. supposing that all prior `DocumentChange` objects
* have been applied). Is `-1` for 'added' events.
*/
readonly oldIndex: number;
/**
* The index of the changed document in the result set immediately after
* this `DocumentChange` (i.e. supposing that all prior `DocumentChange`
* objects and the current `DocumentChange` object have been applied).
* Is -1 for 'removed' events.
*/
readonly newIndex: number;
}
/**
* A `DocumentSnapshot` contains data read from a document in your Firestore
* database. The data can be extracted with `.data()` or `.get(<field>)` to
* get a specific field.
*
* For a `DocumentSnapshot` that points to a non-existing document, any data
* access will return 'undefined'. You can use the `exists()` method to
* explicitly verify a document's existence.
*/
export class DocumentSnapshot<
T = DocumentData
> extends LiteDocumentSnapshot<T> {
private readonly _firestoreImpl: Firestore;
/**
* Metadata about the `DocumentSnapshot`, including information about its
* source and local modifications.
*/
readonly metadata: SnapshotMetadata;
/** @hideconstructor protected */
constructor(
readonly _firestore: Firestore,
userDataWriter: AbstractUserDataWriter,
key: DocumentKey,
document: Document | null,
metadata: SnapshotMetadata,
converter: UntypedFirestoreDataConverter<T> | null
) {
super(_firestore, userDataWriter, key, document, converter);
this._firestoreImpl = _firestore;
this.metadata = metadata;
}
/**
* Property of the `DocumentSnapshot` that signals whether or not the data
* exists. True if the document exists.
*/
exists(): this is QueryDocumentSnapshot<T> {
return super.exists();
}
/**
* Retrieves all fields in the document as an `Object`. Returns `undefined` if
* the document doesn't exist.
*
* By default, `serverTimestamp()` values that have not yet been
* set to their final value will be returned as `null`. You can override
* this by passing an options object.
*
* @param options - An options object to configure how data is retrieved from
* the snapshot (for example the desired behavior for server timestamps that
* have not yet been set to their final value).
* @returns An `Object` containing all fields in the document or `undefined` if
* the document doesn't exist.
*/
data(options: SnapshotOptions = {}): T | undefined {
if (!this._document) {
return undefined;
} else if (this._converter) {
// We only want to use the converter and create a new DocumentSnapshot
// if a converter has been provided.
const snapshot = new QueryDocumentSnapshot(
this._firestore,
this._userDataWriter,
this._key,
this._document,
this.metadata,
/* converter= */ null
);
return this._converter.fromFirestore(snapshot, options);
} else {
return this._userDataWriter.convertValue(
this._document.data.value,
options.serverTimestamps
) as T;
}
}
/**
* Retrieves the field specified by `fieldPath`. Returns `undefined` if the
* document or field doesn't exist.
*
* By default, a `serverTimestamp()` that has not yet been set to
* its final value will be returned as `null`. You can override this by
* passing an options object.
*
* @param fieldPath - The path (for example 'foo' or 'foo.bar') to a specific
* field.
* @param options - An options object to configure how the field is retrieved
* from the snapshot (for example the desired behavior for server timestamps
* that have not yet been set to their final value).
* @returns The data at the specified field location or undefined if no such
* field exists in the document.
*/
// We are using `any` here to avoid an explicit cast by our users.
// eslint-disable-next-line @typescript-eslint/no-explicit-any
get(fieldPath: string | FieldPath, options: SnapshotOptions = {}): any {
if (this._document) {
const value = this._document.data.field(
fieldPathFromArgument('DocumentSnapshot.get', fieldPath)
);
if (value !== null) {
return this._userDataWriter.convertValue(
value,
options.serverTimestamps
);
}
}
return undefined;
}
}
/**
* A `QueryDocumentSnapshot` contains data read from a document in your
* Firestore database as part of a query. The document is guaranteed to exist
* and its data can be extracted with `.data()` or `.get(<field>)` to get a
* specific field.
*
* A `QueryDocumentSnapshot` offers the same API surface as a
* `DocumentSnapshot`. Since query results contain only existing documents, the
* `exists` property will always be true and `data()` will never return
* 'undefined'.
*/
export class QueryDocumentSnapshot<
T = DocumentData
> extends DocumentSnapshot<T> {
/**
* Retrieves all fields in the document as an `Object`.
*
* By default, `serverTimestamp()` values that have not yet been
* set to their final value will be returned as `null`. You can override
* this by passing an options object.
*
* @override
* @param options - An options object to configure how data is retrieved from
* the snapshot (for example the desired behavior for server timestamps that
* have not yet been set to their final value).
* @returns An `Object` containing all fields in the document.
*/
data(options: SnapshotOptions = {}): T {
return super.data(options) as T;
}
}
/**
* A `QuerySnapshot` contains zero or more `DocumentSnapshot` objects
* representing the results of a query. The documents can be accessed as an
* array via the `docs` property or enumerated using the `forEach` method. The
* number of documents can be determined via the `empty` and `size`
* properties.
*/
export class QuerySnapshot<T = DocumentData> {
/**
* Metadata about this snapshot, concerning its source and if it has local
* modifications.
*/
readonly metadata: SnapshotMetadata;
/**
* The query on which you called `get` or `onSnapshot` in order to get this
* `QuerySnapshot`.
*/
readonly query: Query<T>;
private _cachedChanges?: Array<DocumentChange<T>>;
private _cachedChangesIncludeMetadataChanges?: boolean;
/** @hideconstructor */
constructor(
readonly _firestore: Firestore,
readonly _userDataWriter: AbstractUserDataWriter,
query: Query<T>,
readonly _snapshot: ViewSnapshot
) {
this.metadata = new SnapshotMetadata(
_snapshot.hasPendingWrites,
_snapshot.fromCache
);
this.query = query;
}
/** An array of all the documents in the `QuerySnapshot`. */
get docs(): Array<QueryDocumentSnapshot<T>> {
const result: Array<QueryDocumentSnapshot<T>> = [];
this.forEach(doc => result.push(doc));
return result;
}
/** The number of documents in the `QuerySnapshot`. */
get size(): number {
return this._snapshot.docs.size;
}
/** True if there are no documents in the `QuerySnapshot`. */
get empty(): boolean {
return this.size === 0;
}
/**
* Enumerates all of the documents in the `QuerySnapshot`.
*
* @param callback - A callback to be called with a `QueryDocumentSnapshot` for
* each document in the snapshot.
* @param thisArg - The `this` binding for the callback.
*/
forEach(
callback: (result: QueryDocumentSnapshot<T>) => void,
thisArg?: unknown
): void {
this._snapshot.docs.forEach(doc => {
callback.call(
thisArg,
new QueryDocumentSnapshot<T>(
this._firestore,
this._userDataWriter,
doc.key,
doc,
new SnapshotMetadata(
this._snapshot.mutatedKeys.has(doc.key),
this._snapshot.fromCache
),
this.query.converter
)
);
});
}
/**
* Returns an array of the documents changes since the last snapshot. If this
* is the first snapshot, all documents will be in the list as 'added'
* changes.
*
* @param options - `SnapshotListenOptions` that control whether metadata-only
* changes (i.e. only `DocumentSnapshot.metadata` changed) should trigger
* snapshot events.
*/
docChanges(options: SnapshotListenOptions = {}): Array<DocumentChange<T>> {
const includeMetadataChanges = !!options.includeMetadataChanges;
if (includeMetadataChanges && this._snapshot.excludesMetadataChanges) {
throw new FirestoreError(
Code.INVALID_ARGUMENT,
'To include metadata changes with your document changes, you must ' +
'also pass { includeMetadataChanges:true } to onSnapshot().'
);
}
if (
!this._cachedChanges ||
this._cachedChangesIncludeMetadataChanges !== includeMetadataChanges
) {
this._cachedChanges = changesFromSnapshot(this, includeMetadataChanges);
this._cachedChangesIncludeMetadataChanges = includeMetadataChanges;
}
return this._cachedChanges;
}
}
/** Calculates the array of `DocumentChange`s for a given `ViewSnapshot`. */
export function changesFromSnapshot<T>(
querySnapshot: QuerySnapshot<T>,
includeMetadataChanges: boolean
): Array<DocumentChange<T>> {
if (querySnapshot._snapshot.oldDocs.isEmpty()) {
// Special case the first snapshot because index calculation is easy and
// fast
let lastDoc: Document;
let index = 0;
return querySnapshot._snapshot.docChanges.map(change => {
debugAssert(
change.type === ChangeType.Added,
'Invalid event type for first snapshot'
);
debugAssert(
!lastDoc ||
newQueryComparator(querySnapshot._snapshot.query)(
lastDoc,
change.doc
) < 0,
'Got added events in wrong order'
);
const doc = new QueryDocumentSnapshot<T>(
querySnapshot._firestore,
querySnapshot._userDataWriter,
change.doc.key,
change.doc,
new SnapshotMetadata(
querySnapshot._snapshot.mutatedKeys.has(change.doc.key),
querySnapshot._snapshot.fromCache
),
querySnapshot.query.converter
);
lastDoc = change.doc;
return {
type: 'added' as DocumentChangeType,
doc,
oldIndex: -1,
newIndex: index++
};
});
} else {
// A `DocumentSet` that is updated incrementally as changes are applied to use
// to lookup the index of a document.
let indexTracker = querySnapshot._snapshot.oldDocs;
return querySnapshot._snapshot.docChanges
.filter(
change => includeMetadataChanges || change.type !== ChangeType.Metadata
)
.map(change => {
const doc = new QueryDocumentSnapshot<T>(
querySnapshot._firestore,
querySnapshot._userDataWriter,
change.doc.key,
change.doc,
new SnapshotMetadata(
querySnapshot._snapshot.mutatedKeys.has(change.doc.key),
querySnapshot._snapshot.fromCache
),
querySnapshot.query.converter
);
let oldIndex = -1;
let newIndex = -1;
if (change.type !== ChangeType.Added) {
oldIndex = indexTracker.indexOf(change.doc.key);
debugAssert(oldIndex >= 0, 'Index for document not found');
indexTracker = indexTracker.delete(change.doc.key);
}
if (change.type !== ChangeType.Removed) {
indexTracker = indexTracker.add(change.doc);
newIndex = indexTracker.indexOf(change.doc.key);
}
return {
type: resultChangeType(change.type),
doc,
oldIndex,
newIndex
};
});
}
}
export function resultChangeType(type: ChangeType): DocumentChangeType {
switch (type) {
case ChangeType.Added:
return 'added';
case ChangeType.Modified:
case ChangeType.Metadata:
return 'modified';
case ChangeType.Removed:
return 'removed';
default:
return fail('Unknown change type: ' + type);
}
}
// TODO(firestoreexp): Add tests for snapshotEqual with different snapshot
// metadata
/**
* Returns true if the provided snapshots are equal.
*
* @param left - A snapshot to compare.
* @param right - A snapshot to compare.
* @returns true if the snapshots are equal.
*/
export function snapshotEqual<T>(
left: DocumentSnapshot<T> | QuerySnapshot<T>,
right: DocumentSnapshot<T> | QuerySnapshot<T>
): boolean {
if (left instanceof DocumentSnapshot && right instanceof DocumentSnapshot) {
return (
left._firestore === right._firestore &&
left._key.isEqual(right._key) &&
(left._document === null
? right._document === null
: left._document.isEqual(right._document)) &&
left._converter === right._converter
);
} else if (left instanceof QuerySnapshot && right instanceof QuerySnapshot) {
return (
left._firestore === right._firestore &&
queryEqual(left.query, right.query) &&
left.metadata.isEqual(right.metadata) &&
left._snapshot.isEqual(right._snapshot)
);
}
return false;
}