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Custom Queries

As a product gets more complicated, adding custom queries to the schema becomes essential. This shows how to do so.

Viewer

The Viewer, which was introduced earlier is never automatically exposed in the GraphQL schema because there's no uniformity in what can be exposed across different products. So if/when this needs to be exposed, it has to be done manually.

Here's an example which exposes Viewer :

src/graphql/resolvers/viewer.ts
@gqlObjectType({ name: "Viewer" })
export class ViewerType {
constructor(private viewer: Viewer) {}

@gqlField({ type: GraphQLID, nullable: true })
async viewerID() {

const user = await this.user();
if (!user) {
return null;
}
return encodeGQLID(user);

}

@gqlField({ type: User, nullable: true })
async user(): Promise<User | null> {

const v = this.viewer.viewerID;
if (!v) {
return null;
}
return User.loadX(this.viewer, v);

}
}

export default class ViewerResolver {
@gqlQuery({ name: "viewer", type: ViewerType })
viewer(@gqlContextType() context: RequestContext): ViewerType {

return new ViewerType(context.getViewer());

}
}

This updates the GraphQL schema as follows:

src/graphql/generated/schema.gql
type Viewer {
viewerID: ID
user: User
}

Here's what's happening here:

  • This adds a new object Viewer to the GraphQLSchema represented by the class ViewerType.
  • Viewer object has 2 fields:
    • nullable viewerID of type ID
    • nullable user of type User
  • New field viewer added to Query Type.

This uses the following concepts to implement this:

gqlQuery

This adds a new field to the GraphQL Query type. See example usage above.

Accepts the following options which overlap with gqlField:

  • name for the name of the GraphQL field
  • description of the field
  • type: type returned by the field

gqlObjectType

Adds a new object to the schema. See example usage above.

Options:

name

Name of the object. If not specified, defaults to the name of the class

description

Description of the object. Will be added to the Schema and exposed in tools like GraphiQL or Playground.