@microbackend/plugin-graphql-core

Microbackend plugin to add core support for GraphQL, without any specific server implementation.

Installation

npx microbackend plugin add @microbackend/plugin-graphql-core

Usage

Directive

Define new directives under src/extension/graphql/directive:

• Using MicrobackendSchemaTransformer:

// extension/graphql/directive/always_return_3.ts
import { getDirective, MapperKind, mapSchema } from "@graphql-tools/utils";
import { MicrobackendSchemaTransformer } from "@microbackend/plugin-graphql-core";
import gql from "graphql-tag";

export default class AlwaysReturn3 extends MicrobackendSchemaTransformer {
  get transformer(): MicrobackendSchemaTransformer["transformer"] {
    return ({ schema }) => {
      return mapSchema(schema, {
        [MapperKind.OBJECT_FIELD]: (fieldConfig) => {
          const directive = getDirective(
            schema,
            fieldConfig,
            this.args.directiveName
          );

          if (directive != null) {
            fieldConfig.resolve = async () => {
              return 3;
            };

            return fieldConfig;
          }

          return undefined;
        },
      });
    };
  }

  get typeDefs() {
    return gql`
    directive @${this.args.directiveName} on FIELD_DEFINITION
    `;
  }
}

• Using IMicrobackendSchemaTransformerCreator:

// extension/graphql/directive/always_return_1.ts
import { getDirective, MapperKind, mapSchema } from "@graphql-tools/utils";
import gql from "graphql-tag";
import { IMicrobackendSchemaTransformerCreator } from "@microbackend/plugin-graphql-core";

export default ((): IMicrobackendSchemaTransformerCreator => {
  return ({ directiveName }) => {
    return {
      transformer: ({ schema }) => {
        return mapSchema(schema, {
          [MapperKind.OBJECT_FIELD]: (fieldConfig) => {
            const directive = getDirective(schema, fieldConfig, directiveName);

            if (directive != null) {
              fieldConfig.resolve = async () => {
                return 1;
              };

              return fieldConfig;
            }

            return undefined;
          },
        });
      },
      typeDefs: gql`
      directive @${directiveName} on FIELD_DEFINITION
      `,
    };
  };
})();

These directives will be loaded at runtime automatically; the names of the directive files shall become the names of the directives themselves, like so:

extend type Query {
  test1: Int! @always_return_1;
  test2: Int! @always_return_3;
}