Cordova Firestore Plugin (for Capacitor v2+)

A Google Firebase Firestore plugin to enable realtime synchronisation between app and cloud and automatically handle limited connectivity.

What is Firestore?

From the Google documentation (https://firebase.google.com/docs/firestore/):

Cloud Firestore is a flexible, scalable database for mobile, web, and server development from Firebase and Google Cloud Platform. Like Firebase Realtime Database, it keeps your data in sync across client apps through realtime listeners and offers offline support for mobile and web so you can build responsive apps that work regardless of network latency or Internet connectivity. Cloud Firestore also offers seamless integration with other Firebase and Google Cloud Platform products, including Cloud Functions

Supported platforms

This plugin supports the following platforms:

• Android
• iOS

Installation

Install the plugin

yarn add cordova-plugin-firestore

Android specific installation

Download google-services.json to (your_project_dir)/google-services.json

Hint: Get a config file for your Android App

You must ensure that google-services.json is put in the correct location: app/google-services.json.

iOS specific installation

Download GoogleService-Info.plist to (your_project_dir)/GoogleService-Info.plist

Hint: Get a config file for your iOS App

Firestore configuration

It is good practice to make sure your Firestore database is only accessible for authorised users, at least for write operations. It is recommended you take time to understand Firestore rules.

An example that only allows access for authorised users is shown below:

service cloud.firestore {
  match /databases/{database}/documents {
    match /{document=**} {
      allow read, write : if request.auth != null;
    }
  }
}

Authenticating users is beyond the scope of this plugin, but the cordova-plugin-firebaseui-auth is one such plugin you can use to achieve this which will work alongside this plugin.

Dependencies

Promises

This plugin uses Promises. If you want to use this with Android 4.4 then you will need to include a Promise polyfill.

Example

A simple example is shown below which sets up the necessary options, initialises the database and then adds a document to a users collection:

var options = {
  "datePrefix": '__DATE:',
  "fieldValueDelete": "__DELETE",
  "fieldValueServerTimestamp" : "__SERVERTIMESTAMP",
  "persist": true
};

Firestore.initialise(options).then(function(db) {
  // Add a second document with a generated ID.
  db.get().collection("users").add({
      first: "Alan",
      middle: "Mathison",
      last: "Turing",
      born: 1912
  })
  .then(function(docRef) {
      console.log("Document written with ID: ", docRef.id);
  })
  .catch(function(error) {
      console.error("Error adding document: ", error);
  });
});

options.config

In the above example this is being used for the browser version, but it can also be used for Android and iOS to specify different databases than the default in the google-services.json and GoogleService-Info.plist files.

What is supported?

Firestore

• collection(collectionPath)
• runTransaction(updateFunction)
• doc(id)

DocumentSnapshot and QueryDataSnapshot

• data()
• get(fieldPath)
• exists
• id
• ref

QuerySnapshot

• docs
• empty
• size

DocumentReference

• collection(collectionPath)
• delete()
• get()
• onSnapshot(optionsOrObserverOrOnNext, observerOrOnNextOrOnError, onError)
• set(data, options)
• update(data)
• id
• parent

Query

• endAt(snapshotOrVarArgs)
• endBefore(snapshotOrVarArgs)
• limit(limit)
• orderBy(field, direction)
• get()
• onSnapshot(optionsOrObserverOrOnNext, observerOrOnNextOrOnError, onError)
• startAfter(snapshotOrVarArgs)
• startAt(snapshotOrVarArgs)
• where(fieldPath, opStr, passedValue)

CollectionReference (inherits from Query)

• add(data)
• id
• doc(id)
• parent

Transaction

• get()
• delete()
• set()
• update()

FieldValue

• FieldValue.delete()
• FieldValue.serverTimestamp()

GeoPoint

• Firestore.GeoPoint(latitude, longitude)

Timestamp

• Firestore.Timestamp(seconds, nanoseconds)

Dates

Because data is transferred to the client as JSON there is extra logic in place to handle the conversion of dates for some operations.

When initialising the plugin you can set up a prefix that is applied to a string value which is used to identify it as a date. The default prefix is __DATE:

Therefore, when a date field is retrieved from the database by the native code it will be transferred in the JSON looking similar to the following:

{
    "dateField" : "__DATE:123456789"
}

The number is seconds since epoch.

The client will receive the field as a Javascript Date.

This conversion also happens when specifying a field in a where condition.

The behavior for Date objects stored in Firestore is going to change
AND YOUR APP MAY BREAK.
To hide this warning and ensure your app does not break, you need to add the
following code to your app before calling any other Cloud Firestore methods:

  const firestore = firebase.firestore();
  const settings = {/* your settings... */ timestampsInSnapshots: true};
  firestore.settings(settings);

With this change, timestamps stored in Cloud Firestore will be read back as
Firebase Timestamp objects instead of as system Date objects. So you will also
need to update code expecting a Date to instead expect a Timestamp. For example:

  // Old:
  const date = snapshot.get('created_at');
  // New:
  const timestamp = snapshot.get('created_at');
  const date = timestamp.toDate();

Please audit all existing usages of Date when you enable the new behavior. In a
future release, the behavior will change to the new behavior, so if you do not
follow these steps, YOUR APP MAY BREAK.

FieldValue constants

Similar to the situation with dates, there are special values used for FieldValue values:

• FieldValue.delete() equates to __DELETE
• FieldValue.serverTimestamp() equates to __SERVERTIMESTAMP

These values can be changed when initialisation is performed.

Nested collections

Nested collections are supported. This can take either form as follows:

db.get().collection("mycollection").doc("mydoc").collection("mysubcollection");
db.get().collection("mycollection/mydoc/mysubcollection");

Note that the second form is slightly more efficient as it results in less objects being instantiated.

Learnings and notes

I have learnt a number of things whilst implementing this:

• The documentation states that the database cannot be initialised in a seperate thread when using persistence. In my experience this should say it cannot be used in multiple threads.
• Yes, I did spell initialise() with an 's' - Original plugin developer @ReallySmallSoftware is from the UK