03 Data Persistence.md

# Data Persistence

```shell
$ firebase init database
  ? What file should be used for Database Rules? (database.rules.json)
  ? File database.rules.json already exists. Do you want to overwrite it
    with the Database Rules for  from the Firebase Console? (y)
  ✔   Database Rules for  have been downloaded to database.rules.json.
      Future modifications to database.rules.json will update Database Rules
      when you run firebase deploy.

  i   Writing configuration info to firebase.json...
  i   Writing project information to .firebaserc...

  ✔   Firebase initialization complete!
```

Now you will need to log onto the firebase console for your app and make the following changes:

1. Access the **Database** tab and click on the **Create database** button.
2. Choose to _start in production mode_.
3. For region choose _eur3 (europe-west)_.
4. Wait for the provisioning process to complete.

At present the permissions are restrictive and prevent anyone from adding or viewing the documents. Access the **Rules** tab and change the rules to the following:

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

This gives any logged in user read/write access to all documents.


```
// allow any authorised user to read and write the documents
service cloud.firestore {
  match /databases/{database}/documents {
    match /{document=**} {
      allow read, write: if request.auth != null;
    }
  }
}
```

```javascript
// updating a record
db.collection('todo')  
  .doc('qIIz49uGTyHg737BYNSP')   
  .update({        
     title: "JavScript MVC Design Pattern"     
  })
```