GraphQL

Implements GraphQL over HTTP. Single POST /graphql endpoint with query and mutation routing. The serializer filters response fields to match the client’s selection set.

• Spec: graphql.org
• MIME: application/json
• Serializer: GraphQLSerializer
• Routing: Body-matched (single endpoint)

Setup

import crate.protocols.graphql.policy;

auto crateRouter = router.crateSetup!GraphQL;
crateRouter.add(userCrate);

Generated Operations

All operations use POST /graphql:

Queries:

• user(id: ID!): User — get one
• users: [User] — list all

Mutations:

• createUser(input: UserInput!): User
• updateUser(id: ID!, input: UserInput!): User
• replaceUser(id: ID!, input: UserInput!): User
• deleteUser(id: ID!): Boolean

Request Format

Query:

{
  "query": "{ users { _id name email } }"
}

Mutation:

{
  "query": "mutation { createUser(input: { name: \"Alice\" }) { _id name } }"
}

Field Selection

The GraphQLSerializer filters the response to only include fields requested in the selection set. If you query { users { _id name } }, the response omits email and other fields.

Schema Introspection

GraphQL registers a base operation via onRouterInit to handle schema introspection queries. The schema is built from all registered models.

Not Yet Supported

• Subscriptions: No WebSocket subscription support
• Fragments: No named fragment support
• Introspection: No __schema or __type queries
• Custom scalars: No custom scalar type definitions
• Directives: No @deprecated, @skip, @include, or custom directives
• Union / interface types: Not supported
• Batched queries: No multiple queries per request

Custom Base URL

auto crateRouter = router.crateSetup!(GraphQLPolicy!(PolicyConfig("/api")));
// Endpoint at POST /api/graphql