This template shows how to keep track of the date at which the Firebase Database or a subset of a firebase Database was last modified.

See file functions/index.js for the code.

This is done by simply updating a lastmodified attribute on the parent of the node which is tracked (for instance at the root of the Database).

The dependencies are listed in functions/package.json .

As an example we'll be using a simple chat database structure:

/functions-project-12345
    /chat
        /key-123456
            username: "Mat"
            text: "Hey Bob!"
        /key-123457
            username: "Bob"
            text: "Hey Mat"

The function will write to /lastmodified :

/functions-project-12345
    /lastmodified: 1234567890
    /chat
        /key-123456
            username: "Mat"
            text: "Hey Bob!"
        /key-123457
            username: "Bob"
            text: "Hey Mat"

The following security rules ensures only a Function with admin access can update the lastmodified attribute.

{
  "rules": {
    "lastmodified": {
        ".write": "false",
        ".read": "true"
    }
  }
}