We use GraphQL transformers. Examples are Graphback, Dgraph, AWS Amplify. This library provides function that given any GraphQL schema creates new GraphQL schemas basing on transformer functions.
npm i transform-graphqlProvide original schema with your transformer directives and an array of transformer functions defined by TransformerDef type
import { TransformGraphQLSchema } from 'transform-graphql'; const transformedSchema = TransformGraphQLSchema({ schema: inputSchema, transformers: [transformerCRUD] }); This short example simply shows what transform GraphQL is about:
Given the schema:
type Post @model{ name: String! content: String! createdAt: String! } type Query{ version:String } type Mutation{ version:String } directive @model on OBJECTwhere model is our actual transformer
We expect schema to be transformed into
directive @model on OBJECT input CreatePost{ name: String! content: String! createdAt: String! } input DetailsPost{ id: String! } type Mutation{ version: String post: PostMutation } type Post @model{ name: String! content: String! createdAt: String! } type PostMutation{ create( post: CreatePost ): String! update( post: UpdatePost details: DetailsPost ): String! remove( details: DetailsPost ): String! } type PostQuery{ list: [Post!]! getByDetails( details: DetailsPost ): Post } type Query{ version: String post: PostQuery } input UpdatePost{ name: String! content: String! createdAt: String! } schema{ query: Query, mutation: Mutation }And the transformer code should look like this
const inputSchema = ` type Post @model{ name: String! content: String! createdAt: String! } type Query{ version:String } type Mutation{ version:String }` const transformerCRUD: TransformerDef = { transformer: ({ field, operations }) => { if (!field.args) { throw new Error('Model can be used only for types'); } if (!operations.query) { throw new Error('Query type required'); } if (!operations.mutation) { throw new Error('Query type required'); } return ` input Create${field.name}{ ${TreeToGraphQL.parse({ nodes: field.args })} } input Update${field.name}{ ${TreeToGraphQL.parse({ nodes: field.args })} } input Details${field.name}{ id: String! } type ${field.name}Query{ list: [${field.name}!]! getByDetails(details: Details${field.name}): ${field.name} } type ${field.name}Mutation{ create( ${field.name[0].toLowerCase() + field.name.slice(1)}: Create${field.name} ): String! update( ${field.name[0].toLowerCase() + field.name.slice(1)}: Update${field.name}, details: Details${ field.name } ): String! remove( details: Details${field.name} ): String! } extend type ${operations.query.name}{ ${field.name[0].toLowerCase() + field.name.slice(1)}: ${field.name}Query } extend type ${operations.mutation.name}{ ${field.name[0].toLowerCase() + field.name.slice(1)}: ${field.name}Mutation } `; }, directiveName: 'model', }; const transformedSchema = TransformGraphQLSchema({ schema: GraphQLTransform, transformers: [transformerCRUD] }); //transfomed schema should look like in the example- provide CLI
- provide examples