> For the complete documentation index, see [llms.txt](https://lionstudios.gitbook.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://lionstudios.gitbook.io/readme/features/remote-storage/firestore.md).

# Firestore

### **Introduction**

A flexible, scalable database for our games. Like realtime database, it keeps user data in sync across client apps.

### **Prerequisites**

* You must have access to Firebase console project of the game

### Create Firestore Database

1. Go to the Firestore Database on the sidebar
2. Click on “Create database”

<figure><img src="/files/eFpsk74KN7FZaVZuY6rB" alt="" width="563"><figcaption></figcaption></figure>

3. It will present a popup to select the location of the database. Keep the default values
4. Click Next

<figure><img src="/files/1bR05o647sDxIEbvDwC0" alt="" width="563"><figcaption></figcaption></figure>

5. Select “Start in production mode” and click "Create"

<figure><img src="/files/xrWd47bdaO6PTOON7GYC" alt="" width="563"><figcaption></figcaption></figure>

6. Copy-paste the code block given below into the `Rules` window of your Firestore Database.

```firestore-security-rules
rules_version = '2';
service cloud.firestore 
{
  match /databases/{database}/documents 
  {
    function signedIn() { return request.auth != null; }
  
    // Device-like IDs: 32-hex OR UUID-with-dashes OR generic 16–64 hex
    function isDeviceId(id) {
      return
        id.matches('^[0-9A-Fa-f]{32}$') ||                         // 32 hex
        id.matches('^[0-9A-Fa-f]{8}-[0-9A-Fa-f]{4}-[0-9A-Fa-f]{4}-[0-9A-Fa-f]{4}-[0-9A-Fa-f]{12}$') || // UUID
        id.matches('^[0-9A-Fa-f]{16,64}$');                         // other hex lengths (e.g., 16, 40, 64)
    }
       
    // /<anyCollection>/<UID or deviceId>
    match /{collectionId}/{userId} {
      allow read, write: if signedIn() && (
        request.auth.uid == userId ||      // own UID doc
        isDeviceId(userId)                 // any deviceId doc (see caveat)
      );
    }
       
    // Any depth under those docs
    match /{collectionId}/{userId}/{document=**} {
      allow read, write: if signedIn() && (
        request.auth.uid == userId ||
        isDeviceId(userId)
      );
    }
       
    // Deny everything else
    match /{document=**} {
      allow read, write: if false;
    }
  }
}
```

7. Click on `Authentication/Sign-in method` and click the "Add new provider" button. Enable the following providers:

   <figure><img src="/files/7Ww81TI3XIHSdq8IZTFR" alt=""><figcaption></figcaption></figure>

   * [**Email/Password Auth**](/readme/features/remote-storage/firestore/email-password-auth.md) — **Required**. Base authentication for Remote Storage.
   * [**Facebook Auth**](/readme/features/remote-storage/firestore/facebook-auth.md) — Optional. Enables cross-device data sync via Facebook login.

<p align="center"><br><strong>At this point, Firestore &#x26; Firebase Auth dashboard setup is complete!!</strong></p>

### Configure Firestore in Unity

1. Install the Cloud Firestore & Firebase Authentication packages from Lion Registry under My Registries→ Lion Studios - Third Party SDKs→ Cloud Firestore.

<figure><img src="/files/Uo6st1vndL25mstkuEAu" alt="" width="563"><figcaption><p>Install Firestore And Auth</p></figcaption></figure>

### Implementation

#### Merge Conflict Data

If you're using Firestore as your save data backend, pass a `MergeConflictData` object to your `RemoteStorage.Save(MergeConflictData)` calls. This data drives automatic conflict resolution when syncing data between devices.

This **MergeConflictData** object has the following fields you can set.

* **`PlayerXP`**: This is where you pass information about the players progression in the game. If you have any internal progression tracking metric then use that here.
  * **Tip:** In the case that if your game doesn't have a PlayerXP equivalent, you should pass some data variable that increases every time the save method is called.
* **`LastPurchaseUtc`**: Set this to the timestamp of the user's most recent in-app purchase. You will have to keep track of this timestamp internally.

Below is an example of how to use it:

```csharp
MergeConflictData data = new MergeConflictData();
data = RemoteStorage.CurrentMergeConflictData ?? new MergeConflictData();
data.PlayerXP += amount;
data.LastPurchaseUtc = InternalDataManager.GetLastPurchaseTime(); // Your logic here
bool synced = await RemoteStorage.Save(data);
```

If there is a conflict between two device's data, then our system chooses user data depending upon,

* Whichever device has the most recent IAP purchase time
* Higher value of playerXP
* Most recent save time (This save time is tracked internally by us)


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