@apollographql/graphql-language-service-parser

What is @apollographql/graphql-language-service-parser?

@apollographql/graphql-language-service-parser is a parser for GraphQL language services. It provides tools to parse GraphQL queries, mutations, and subscriptions, making it easier to build GraphQL language services, linters, and other tools that need to understand GraphQL syntax.

What are @apollographql/graphql-language-service-parser's main functionalities?

Parsing GraphQL Queries

This feature allows you to parse a GraphQL query string into an Abstract Syntax Tree (AST). The AST can then be used for further analysis or transformation.

const { parse } = require('@apollographql/graphql-language-service-parser');
const query = `
  query GetUser($id: ID!) {
    user(id: $id) {
      name
      email
    }
  }
`;
const ast = parse(query);
console.log(JSON.stringify(ast, null, 2));

Handling Syntax Errors

This feature demonstrates how to handle syntax errors when parsing a GraphQL query. If the query is invalid, an error will be thrown, which can be caught and handled appropriately.

const { parse } = require('@apollographql/graphql-language-service-parser');
const invalidQuery = `
  query GetUser($id: ID!) {
    user(id: $id) {
      name
      email
    }
`;
try {
  const ast = parse(invalidQuery);
} catch (error) {
  console.error('Syntax Error:', error.message);
}

Parsing GraphQL Fragments

This feature allows you to parse GraphQL fragments, which can be reused in multiple queries or mutations. The parsed AST can be used to understand the structure of the fragment.

const { parse } = require('@apollographql/graphql-language-service-parser');
const fragment = `
  fragment UserFields on User {
    name
    email
  }
`;
const ast = parse(fragment);
console.log(JSON.stringify(ast, null, 2));

Other packages similar to @apollographql/graphql-language-service-parser

graphql

The 'graphql' package is the reference implementation of GraphQL for JavaScript. It includes a parser, schema utilities, and execution engine. While it provides similar parsing capabilities, it is more comprehensive and includes tools for executing GraphQL queries and building schemas.

graphql-tools

The 'graphql-tools' package provides a set of utilities for building and manipulating GraphQL schemas. It includes schema stitching, mocking, and other advanced features. While it does not focus solely on parsing, it offers a broader set of tools for working with GraphQL.

graphql-tag

The 'graphql-tag' package is used to parse GraphQL query strings into ASTs. It is commonly used in client-side applications to define GraphQL queries. While it offers similar parsing capabilities, it is more lightweight and focused on client-side usage.

README

graphql-language-service-parser

An online immutable parser for GraphQL, designed to be used as part of syntax-highlighting and code intelligence tools such as for the GraphQL Language Service and codemirror-graphql.