gql-types-generator

gql-types-generator

Package to generate TypeScript types depending on GraphQL scheme, mutations and queries.

Currently supported GraphQL entities: type, interface, input, type and interface fields arguments, operations (of any kind and selections).

GraphQL entities to be supported in near future: fragments, inline fragments, directives.

TLDR;

If you dont want to read a lot of text and documentation, try to compile your scheme and look what happens. You can find an example here. Just use command in command file.

Install

npm install --save gql-types-generator

yarn add gql-types-generator

Usage

Command line interface

After installation of package is done, gql-types-generator command becomes available. Type to get help:

$ gql-types-generator --help
Usage: gql-types-generator [options] <schema-globs>

Options:
  --operations <globs>             globs to find queries and mutations
  --operations-file <filename>     operations file name. If passed, all operations will be placed into a single file
  --operations-wrap                wraps operations with graphql-tag, making exports from operations not strings, but graphql's DocumentNode (default: false)
  --operations-selection-separate  creates separated types for each selection set (default: false)
  --schema-file <filename>         schema file name
  --remove-description             states if description should be removed (default: false)
  --display <sort>                 how to display compiled types. Valid values are "as-is" and "default". By default, generator compiles scalars first, then enums, interfaces, inputs, unions and then types. "as-is" places types as they are placed in schema
                                   (default: "default")
  --scalars <scalars>              defines scalars types. Must be a JSON, where key is scalar name and value is its type
  --output-directory <path>        path to directory where typings will be saved
  -h, --help                       display help for command

When using CLI, each glob will be formatted as process.cwd() + glob. You can pass an array of globs using comma between them like src/schema1.graphql,src/schema2.graphql.

If an error occurring during types compilation, library returns code 1.

Programmatic control

Library provides such functions as compile, compileSchema and compileOperations to generate types. Type definitions for these functions.

compile(options: CompileOptions)

Name	Type	Description
options.outputDirectory	string	Full path to output directory
options.removeDescription	boolean?	Should library remove descriptions
options.display	DisplayType?	How to display compiled types. Valid values are "as-is" and "default". By default, generator compiles scalars first, then enums, interfaces, inputs, unions and then types. "as-is" places types as they are placed in schema
options.schemaPath	PathType	Defines paths to schema
options.operationsPath	PathType?	Defines paths to operations
options.schemaFileName	string?	Defines schema file name. For example - schema.ts
options.operationsFileName	string?	Defines operations file name. For example - operation.ts. If passed, all operations will be placed into a single file
options.operationsWrap	boolean?	States of compiled types should be graphqls DocumentNode and not string
options.scalars	ScalarsMap?	Defines types of scalars

Example

import {compile} from 'gql-types-generator';
import * as path from 'path';

compile({
  outputDirectory:  path.resolve(__dirname, 'compiled'),
  removeDescription: false,
  display: 'as-is',
  operationsPath: {
    glob: {
      cwd: process.cwd(),
      glob: 'gql/operations/*.graphql'
    }
  },
  schemaPath: {
    path: [
      path.resolve(__dirname, 'gql/schema/part1.graphql'),
      path.resolve(__dirname, 'gql/schema/part2.graphql'),
     ]
  },
  // Or pass schema glob
  schemaPath: {
    glob: {
      cwd: process.cwd(),
      glob: 'gql/schema/*.graphql'
    }
  },
  // Or pass schema definition directly
  schemaPath: {
    definition: 'type Query { ... }'
  },
  operationsPath: {
    path: path.resolve(__dirname, 'gql/getUsers.graphql'),
  },
  schemaFileName: 'my-compiled-schema.ts',
  operationsFileName: 'my-compiled-operations.ts',
  operationsWrap: true,
  scalars: {
    MyCustomScalar: 'Date',
    AnotherScalar: 'number | string | Record<string, string>',
    AndAnotherOneScalar: '"string literal"',
  }
});

compileSchema(options: CompileSchemaOptions)

Name	Type	Description
options.schema	string	Schema definition
options.outputDirectory	string	Full path to output directory
options.fileName	string?	Output schema file name
options.display	DisplayType?	How to display compiled types. Valid values are "as-is" and "default". By default, generator compiles scalars first, then enums, interfaces, inputs, unions and then types. "as-is" places types as they are placed in schema
options.removeDescription	boolean?	Should library remove descriptions
options.scalars	ScalarsMap?	Defines types of scalars

Example

import {compileSchema} from 'gql-types-generator';
import * as path from 'path';

compileSchema({
  schema: 'type Query { ... }',
  outputDirectory: path.resolve(__dirname, 'gql/compiled'),
  fileName: 'my-compiled-schema.ts',
  display: 'default',
  removeDescription: true,
});

compileOperations(options: CompileOperationsOptions)

Name	Type	Description
options.operations	string	Operations definition
options.outputDirectory	string	Full path to output directory
options.schema	GraphQLSchema	Built GQL schema
options.schemaFileName	string	Schema file name. Used to pass in relative imports if they are required
options.removeDescription	boolean?	Should library remove descriptions
options.fileName	string?	Output operations file name. If passed, all operations will be placed into a single file
options.wrapWithTag	boolean?	States of compiled types should be graphqls DocumentNode and not string

Example

import {compileOperations} from 'gql-types-generator';
import * as path from 'path';

compileOperations({
  operations: 'query getUser() { ... } mutation register() { ... }',
  outputDirectory: path.resolve(__dirname, 'gql/compiled'),
  // We can get this value via compileSchema
  schema: gqlSchema,
  schemaFileName: 'my-compiled-schema.ts',
  removeDescription: true,
  fileName: 'my-compiled-operations.ts',
  wrapWithTag: false,
});

Compilation result

Schema

Command creates a directory on passed --output-directory path, generates d.ts definition file and compiled js code. Name of these files are taken from --schema-file argument (schema.ts by default).

d.ts contains all schema types and by default exports constant schema which is a text representation of schema.

Each schema type definition consists of interface and namespace with the same name. All interface fields refers to namespace fields. So, if you want to get some Query field type you could use Query['someField'] or Query.SomeField. They return the same thing. It is recommended to use Query.*-like syntax for better experience.

If --scalars passed, compiled type of scalar will be taken from this map. If scalar not found, it will be any. Must be a JSON with values of type string or number.

Operations

To compile operations, it is required to use --operations argument. This values must be a glob which refers to files where operations are defined.

Library creates single file with name --operations-file if it is passed or 2 separate files d.ts and js for each command with name computed as operationName + toCamelCase(operationType) in directory on passed --output-directory. So, if operation was query getUsers { ... }, created files will be getUsersQuery.d.ts and getUsersQuery.js.

• d.ts exports selection and namespace with Arguments if they exist. Additionally namespace contains subselections represented as other namespaces
• js exports representation of operation

If --operations-wrap passed, wraps each operation string with graphql-tag package making each operation not string, but graphqls Document Node. Useful when you use these operations on frontend with Apollo client.