react-native-firebase/lib/modules/database/snapshot.js

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/**
* @flow
*/
import Reference from './reference.js';
import { isObject, deepGet, deepExists } from './../../utils';
/**
* @class DataSnapshot
* @link https://firebase.google.com/docs/reference/js/firebase.database.DataSnapshot
*/
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export default class Snapshot {
ref: Object;
key: string;
_value: any;
_priority: any;
_childKeys: Array<string>;
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constructor(ref: Reference, snapshot: Object) {
this.key = snapshot.key;
if (ref.key !== snapshot.key) {
this.ref = ref.child(snapshot.key);
} else {
this.ref = ref;
}
// internal use only
this._value = snapshot.value;
this._priority = snapshot.priority === undefined ? null : snapshot.priority;
this._childKeys = snapshot.childKeys || [];
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}
/**
* Extracts a JavaScript value from a DataSnapshot.
* @link https://firebase.google.com/docs/reference/js/firebase.database.DataSnapshot#val
* @returns {any}
*/
val(): any {
// clone via JSON stringify/parse - prevent modification of this._value
if (isObject(this._value) || Array.isArray(this._value)) return JSON.parse(JSON.stringify(this._value));
return this._value;
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}
/**
* Gets another DataSnapshot for the location at the specified relative path.
* @param path
* @link https://firebase.google.com/docs/reference/js/firebase.database.DataSnapshot#forEach
* @returns {Snapshot}
*/
child(path: string): Snapshot {
const value = deepGet(this._value, path);
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const childRef = this.ref.child(path);
return new Snapshot(childRef, {
value,
key: childRef.key,
exists: value !== null,
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// todo this is wrong - child keys needs to be the ordered keys, from FB
// todo potential solution is build up a tree/map of a snapshot and its children
// todo natively and send that back to JS to be use in this class.
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childKeys: isObject(value) ? Object.keys(value) : [],
});
}
/**
* Returns true if this DataSnapshot contains any data.
* @link https://firebase.google.com/docs/reference/js/firebase.database.DataSnapshot#exists
* @returns {boolean}
*/
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exists(): boolean {
return this._value !== null;
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}
/**
* Enumerates the top-level children in the DataSnapshot.
* @link https://firebase.google.com/docs/reference/js/firebase.database.DataSnapshot#forEach
* @param action
*/
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forEach(action: (key: any) => any): boolean {
if (!this._childKeys.length) return false;
let cancelled = false;
for (let i = 0, len = this._childKeys.length; i < len; i++) {
const key = this._childKeys[i];
const childSnapshot = this.child(key);
const returnValue = action(childSnapshot);
if (returnValue === true) {
cancelled = true;
break;
}
}
return cancelled;
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}
/**
* Gets the priority value of the data in this DataSnapshot.
* @link https://firebase.google.com/docs/reference/js/firebase.database.DataSnapshot#getPriority
* @returns {String|Number|null}
*/
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getPriority(): string | number | null {
return this._priority;
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}
/**
* Returns true if the specified child path has (non-null) data.
* @link https://firebase.google.com/docs/reference/js/firebase.database.DataSnapshot#hasChild
* @param path
* @returns {Boolean}
*/
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hasChild(path: string): boolean {
return deepExists(this._value, path);
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}
/**
* Returns whether or not the DataSnapshot has any non-null child properties.
* @link https://firebase.google.com/docs/reference/js/firebase.database.DataSnapshot#hasChildren
* @returns {boolean}
*/
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hasChildren(): boolean {
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return this.numChildren() > 0;
}
/**
* Returns the number of child properties of this DataSnapshot.
* @link https://firebase.google.com/docs/reference/js/firebase.database.DataSnapshot#numChildren
* @returns {Number}
*/
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numChildren(): number {
if (!isObject(this._value)) return 0;
return Object.keys(this._value).length;
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}
/**
* Returns a JSON-serializable representation of this object.
* @link https://firebase.google.com/docs/reference/js/firebase.database.DataSnapshot#toJSON
* @returns {any}
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*/
toJSON(): any {
return this.val();
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}
}