Data Validation

Learn how to validate data before it's written to Firestore.

Basic Validation

service cloud.firestore {
  match /databases/{database}/documents {
    match /posts/{postId} {
      allow write: if request.auth != null
        && request.resource.data.title is string
        && request.resource.data.title.size() > 0
        && request.resource.data.title.size() <= 100;
    }
  }
}

This rule ensures property title from the written data:

• Is a string
• Is not empty
• Is not too long

Advanced Validation

service cloud.firestore {
  match /databases/{database}/documents {
    match /users/{userId} {
      allow write: if request.auth != null
        && request.resource.data.email is string
        && request.resource.data.email.matches('^[^@]+@[^@]+\\.[^@]+$')
        && request.resource.data.age is number
        && request.resource.data.age >= 18;
    }
  }
}

This rule:

• validates email format
• age is a number and greater than 18