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

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/**
* @flow
* Database representation wrapper
*/
import { NativeModules } from 'react-native';
import { Base } from './../base';
import { generatePushID } from './../../utils';
const FirebaseDatabase = NativeModules.RNFirebaseDatabase;
/**
* @class Database
*/
export default class TransactionHandler extends Base {
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constructor(firebase: Object, database: Object, FirebaseDatabaseEvt: Object) {
super(firebase, {});
this.transactions = {};
this.database = database;
this.namespace = 'firebase:database:transaction';
this.transactionListener = FirebaseDatabaseEvt.addListener(
'database_transaction_event',
event => this._handleTransactionEvent(event)
);
}
/**
* Add a new transaction and begin starts it natively.
* @param reference
* @param transactionUpdater
* @param onComplete
* @param applyLocally
*/
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add(
reference: Object,
transactionUpdater: Function,
onComplete?: Function,
applyLocally?: boolean = false
) {
const id = this._generateTransactionId();
this.transactions[id] = {
id,
reference,
transactionUpdater,
onComplete,
applyLocally,
completed: false,
started: true,
};
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FirebaseDatabase.startTransaction(reference.path, id, applyLocally);
}
/**
* INTERNALS
*/
/**
* Uses the push id generator to create a transaction id
* @returns {string}
* @private
*/
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_generateTransactionId(): string {
return generatePushID(this.database.serverTimeOffset);
}
/**
*
* @param event
* @returns {*}
* @private
*/
_handleTransactionEvent(event: Object = {}) {
switch (event.type) {
case 'update':
return this._handleUpdate(event);
case 'error':
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return this._handleError(event);
case 'complete':
return this._handleComplete(event);
default:
this.log.warn(`Unknown transaction event type: '${event.type}'`, event);
return undefined;
}
}
/**
*
* @param event
* @private
*/
_handleUpdate(event: Object = {}) {
let newValue;
const { id, value } = event;
try {
const transaction = this.transactions[id];
// todo handle when transaction no longer exists on js side?
newValue = transaction.transactionUpdater(value);
} finally {
let abort = false;
if (newValue === undefined) {
abort = true;
}
FirebaseDatabase.tryCommitTransaction(id, { value: newValue, abort });
}
}
/**
*
* @param event
* @private
*/
_handleError(event: Object = {}) {
const transaction = this.transactions[event.id];
if (transaction && !transaction.completed) {
transaction.completed = true;
try {
transaction.onComplete(new Error(event.message, event.code), null);
} finally {
setImmediate(() => {
delete this.transactions[event.id];
});
}
}
}
/**
*
* @param event
* @private
*/
_handleComplete(event: Object = {}) {
const transaction = this.transactions[event.id];
if (transaction && !transaction.completed) {
transaction.completed = true;
try {
transaction.onComplete(null, event.committed, Object.assign({}, event.snapshot));
} finally {
setImmediate(() => {
delete this.transactions[event.id];
});
}
}
}
}