Limitations of Apollo Connectors

Apollo Connectors have the following limitations.

Some supergraphs are unsupported

A small fraction of supergraphs will not compose when adding a Connector. If you add a Connector and see a number of unrelated errors after composing (usually related to SATISFIABILITY), then you've likely encountered this limitation.

Abstract schema types are unsupported

Abstract schema types (interface and union) are currently not supported in subgraphs that contain Connectors.

Support for @interfaceObject was added in preview.3.

A workaround for union types is to create a new type that combines all the properties from each possible return type and mark any non-overlapping fields as nullable.

1type Query {
2  products: [Product]
3    @connect(
4      http: { GET: "/products" }
5      selection: """
6      $.results {
7        id
8        title
9        author { name }
10        director { name }
11      }
12      """
13    )
14}
15
16union Product = Book | Film
17
18type Book {
19  id: ID!
20  title: String
21  author: Person!
22}
23
24type Film {
25  id: ID!
26  title: String
27  director: Person!
28}
29
30type Person {
31  id: ID
32  name: String
33}

1type Query {
2  products: [Product]
3    @connect(
4      http: { GET: "https://api.example.com/products" }
5      selection: """
6      $.results {
7        id
8        title
9        author { name }
10        director { name }
11      }
12      """
13    )
14}
15
16type Product {
17  id: ID!
18  title: String!
19  author: Person # nullable
20  director: Person # nullable
21}
22
23type Person {
24  id: ID
25  name: String
26}

Circular references are unsupported

Connectors don't yet support circular references in GraphQL schemas. See troubleshooting for details.

Subscriptions are unsupported

Currently, you can use @connect on fields of the Query and Mutation types, but not on fields of the Subscription type.

Unsupported federation directives

The following Apollo Federation directives are unsupported or partially supported.

@context and @fromContext are unsupported

Support is on the roadmap.

@override is partially unsupported

It's not currently possible to override fields in a subgraph with Connectors.

1type Query {
2  products: [Product] @override(from: "subgraph-b") # ⛔️
3}

1type Query {
2  products: [Product] @connect(...)
3}

The other direction is supported:

1type Query {
2  products: [Product]
3}

1type Query {
2  products: [Product]
3    @override(from: "subgraph-a") # ✅
4    @connect(...)
5}

Interactions with GraphOS Router features

The following GraphOS Router features are not yet supported with Connectors:

• Entity caching

• Rhai scripting & coprocessors

  Extensibility for Connectors is on the roadmap. The router, supergraph, and execution hooks still work as expected, but the Connector equivalent to the subgraph hook is not yet available.