Parsing GraphQL

Lanexio Parser parses both GraphQL executable documents and SDL (Schema Definition Language) with automatic detection. A single function handles both modes.

Quick start

1. Install the package.

   pnpm

   pnpm add @lanexio/parser-grammar-graphql

   npm

   npm install @lanexio/parser-grammar-graphql

   yarn

   yarn add @lanexio/parser-grammar-graphql

2. Parse a query.

   import { parseGraphql } from '@lanexio/parser-grammar-graphql';
   
   const encoder = new TextEncoder();
   const tree = parseGraphql(encoder.encode(`
     query getUser($id: ID!) {
       user(id: $id) {
         name
         email
       }
     }
   `));

3. Parse a schema.

   import { parseGraphql } from '@lanexio/parser-grammar-graphql';
   
   const tree = parseGraphql(encoder.encode(`
     type User {
       id: ID!
       name: String!
       email: String
     }
   `));

Auto-detection

The parser inspects the input and routes to the executable-document parser or the SDL parser automatically. You do not need to specify which mode to use. Input starting with {, query, mutation, subscription, or fragment is treated as an executable document. Input starting with type, interface, enum, union, input, schema, scalar, directive, or extend is treated as SDL.

Inspecting the tree

Each top-level definition is a node in the tree. Operations, fragments, fields, arguments, types, and directives are all represented with GraphqlKind constants. The tree is a zero-copy flat AST — traverse it with a cursor.

const cursor = tree.cursor();
cursor.gotoFirstChild(); // first operation or definition

while (cursor.gotoNextSibling()) {
  console.log(cursor.current.kind);
}

See also

• GraphQL reference page
• GraphQL conformance