GraphQL Connection :

@connection :

The @connection directive enables you to specify relationships between @model types. Currently, this supports one-to-one, one-to-many, and many-to-one relationships. You may implement many-to-many relationships using two one-to-many connections and a joining @model .

Relationships between types are specified by annotating fields on an @model object type with the @connection directive.

Has One :

Example :

type Project @model { id: ID! name: String team: Team @connection }

type Team @model { id: ID! name: String! }

Has Many :

type Post @model { id: ID! title: String! comments: [Comment] @connection(keyName: “byPost”, fields: [“id”]) }

type Comment @model @key(name: “byPost”, fields: [“postID”, “content”]) { id: ID! postID: ID! content: String! }

Belongs to :

You can make a connection bi-directional by adding a many-to-one connection to types that already have a one-to-many connection. In this case you add a connection from Comment to Post since each comment belongs to a post:

type Post @model { id: ID! title: String! comments: [Comment] @connection(keyName: “byPost”, fields: [“id”]) }

type Comment @model @key(name: “byPost”, fields: [“postID”, “content”]) { id: ID! postID: ID! content: String! post: Post @connection(fields: [“postID”]) }

Many-to-Many connections :

Example :

type Post @model { id: ID! title: String! editors: [PostEditor] @connection(keyName: “byPost”, fields: [“id”]) }

Create a join model and disable queries as you don’t need them

and can query through Post.editors and User.posts

type PostEditor @model(queries: null) @key(name: “byPost”, fields: [“postID”, “editorID”]) @key(name: “byEditor”, fields: [“editorID”, “postID”]) { id: ID! postID: ID! editorID: ID! post: Post! @connection(fields: [“postID”]) editor: User! @connection(fields: [“editorID”]) }

type User @model { id: ID! username: String! posts: [PostEditor] @connection(keyName: “byEditor”, fields: [“id”]) }

Limit :

The default number of nested objects is 100. You can override this behavior by setting the limit argument. For example:

type Post @model { id: ID! title: String! comments: [Comment] @connection(limit: 50) }

type Comment @model { id: ID! content: String! }