Versioning and conflict resolution

@versioned

The @versioned directive adds object versioning and conflict resolution to a type. Do not use this directive when leveraging DataStore as the conflict detection and resolution features are automatically handled inside AppSync and are incompatible with the @versioned directive.

Definition

directive @versioned(versionField: String = "version", versionInput: String = "expectedVersion") on OBJECT

Usage

Add @versioned to a type that is also annotate with @model to enable object versioning and conflict detection for a type.

type Post @model @versioned {
  id: ID!
  title: String!
  version: Int!   # <- If not provided, it is added for you.
}

Creating a Post automatically sets the version to 1

mutation Create {
  createPost(input:{
    title:"Conflict detection in the cloud!"
  }) {
    id
    title
    version  # will be 1
  }
}

Updating a Post requires passing the "expectedVersion" which is the object's last saved version

Note: When updating an object, the version number will automatically increment.

mutation Update($postId: ID!) {
  updatePost(
    input:{
      id: $postId,
      title: "Conflict detection in the cloud is great!",
      expectedVersion: 1
    }
  ) {
    id
    title
    version # will be 2
  }
}

Deleting a Post requires passing the "expectedVersion" which is the object's last saved version

mutation Delete($postId: ID!) {
  deletePost(
    input: {
      id: $postId,
      expectedVersion: 2
    }
  ) {
    id
    title
    version
  }
}

Update and delete operations will fail if the expectedVersion does not match the version stored in DynamoDB. You may change the default name of the version field on the type as well as the name of the input field via the versionField and versionInput arguments on the @versioned directive.

Generates

The @versioned directive manipulates resolver mapping templates and will store a version field in versioned objects.