GraphQL-Ruby ships with a few implementations of the connection pattern that you can use out of the box. They support Ruby Arrays, Mongoid, Sequel, and ActiveRecord.
Additionally, connections allow you to limit the number of items returned with
.connection_type to generate a connection type for paginating over objects of a given type:
field :items, Types::ItemType.connection_type, null: false
The generated return type will be called
ItemConnection. Since it ends in
field(...) will automatically be configured with
connection: true. If the connection type’s name doesn’t end in
Connection, you have to add that configuration yourself:
# here's a custom type whose name doesn't end in "Connection", so `connection: true` is required: field :items, Types::ItemConnectionPage, null: false, connection: true
The field will be given some arguments by default:
With connection fields, you can return collection objects from fields or resolvers:
def items object.items # => eg, returns an ActiveRecord Relation end
The collection object (Array, Mongoid relation, Sequel dataset, ActiveRecord relation) will be automatically paginated with the provided arguments. Cursors will be generated based on the offset of nodes in the collection.
If you want to paginate something that isn’t supported out-of-the-box, you can implement your own pagination wrapper and hook it up to GraphQL-Ruby. Read more in Custom Connections.
Sometimes, you have one collection that needs special handling, unlike other instances of its class. For cases like this, you can manually apply the connection wrapper in the resolver. For example:
def items # Get the ActiveRecord relation to paginate relation = object.items # Apply a custom wrapper Connections::ItemsConnection.new(relation) end
This way, you can handle this particular
relation with custom code.
You can apply
max_page_size to limit the number of items returned, regardless of what the client requests.
class MyAppSchema < GraphQL::Schema default_max_page_size 50 end
At runtime, that value will be applied to every connection, unless an override is provided as described below.
field :items, Item.connection_type, null: false, max_page_size: 25
max_page_size:when you apply custom connection wrappers:
def items relation = object.items Connections::ItemsConnection.new(relation, max_page_size: 10) end
To remove a
max_page_size setting, you can pass
nil. That will allow unbounded collections to be returned to clients.