GraphQL-ly

Local GraphQL schema validation for VS Code — catch syntax errors, schema issues, and directive problems in .graphql and .gql files before they reach your API. Built-in AWS AppSync directive support.

Getting Started

1. Install GraphQL-ly from the VS Code Marketplace
2. Open any .graphql or .gql file
3. Errors appear instantly — red squiggles inline, red filenames in the explorer, and error messages right next to the problem line

No configuration files needed. No cloud connection. Just open a file and go.

Features

✅ Syntax Validation

Catches parse-level errors — missing braces, invalid tokens, malformed definitions.

# ❌ Missing closing brace
type Query {
  id: ID!
  name: String
          ← Syntax Error: Expected "}", found <EOF>.

# ❌ Missing colon between field name and type
type Query {
  name String
       ← Syntax Error: Expected ":", found Name "String".

# ❌ Unterminated string
type Query {
  name: "this string never closes
        ← Syntax Error: Unterminated string.

✅ Undefined Type Detection

Flags fields, arguments, and union members that reference types not defined in the schema.

# ❌ "Post" is never defined
type Query {
  getPost: Post
           ← Unknown type "Post".
}

# ❌ Input type doesn't exist
type Query {
  getUser(input: UserInput): String
                 ← Unknown type "UserInput".
}

# ❌ Union references undefined types
union SearchResult = Post | Comment
                     ← Unknown type "Post".

✅ Duplicate Type Detection

Catches when the same type name is defined more than once.

# ❌ "User" defined twice
type User {
  name: String
}

type User {
  email: String
}
← Type "User" was defined more than once.

✅ Duplicate Field Detection

Catches when the same field appears twice in a type.

# ❌ "name" defined twice in Query
type Query {
  name: String
  name: Int
  ← Field "Query.name" can only be defined once.
}

✅ Interface Compliance

Detects when a type claims to implement an interface but is missing required fields.

# ❌ User is missing "createdAt" from Node
interface Node {
  id: ID!
  createdAt: String!
}

type User implements Node {
  id: ID!
  name: String
  ← Type "User" is missing field "Node.createdAt".
}

✅ Undefined Interface / Union Member Detection

Flags when a type implements an interface that doesn't exist, or a union references missing types.

# ❌ "Animal" interface doesn't exist
type Dog implements Animal {
  name: String
}
← Type "Dog" interfaces must be defined. "Animal" is not defined.

✅ Unknown Directive Detection

Flags directives that aren't recognized.

# ❌ @nonexistent is not a known directive
type Query {
  id: ID @nonexistent
         ← Unknown directive "@nonexistent".
}

✅ Directive Misuse Detection

Catches directives used in the wrong location or with missing required arguments.

# ❌ @aws_subscribe belongs on a field, not a type
type Subscription @aws_subscribe(mutations: ["addPost"]) {
  onAddPost: String
}
← Directive "@aws_subscribe" may not be used on OBJECT.

✅ AWS AppSync Directive Support

Recognizes all AppSync authorization and subscription directives — no false positives:

✅ AWS AppSync Scalar Type Support

Recognizes all AppSync built-in scalar types — no false positives:

# ✅ All valid — no errors
type Post @aws_api_key @aws_iam {
  id: ID!
  title: String!
  secret: String @aws_iam
}

type Query {
  publicGet: String @aws_api_key
  authGet: String @aws_auth(cognito_groups: ["Admin"])
}

type Subscription {
  onAdd: String @aws_subscribe(mutations: ["addItem"])
}

✅ File-Level Error Indicators

Files with errors show red in the explorer and tab bar — just like ESLint or TypeScript. You can spot problems without opening the file.

✅ Inline Error Messages

Error descriptions appear in red italic text right next to the problem line — no need to hover or open the Problems panel.

✅ Background Validation

Files stay validated even when they're not the active tab. Switch between files freely — diagnostics persist.

Configuration

Change via Settings → search graphql-ly → select your preferred mode.

When to use multi-file mode: If your schema is split across multiple files (e.g., types.graphql, queries.graphql, mutations.graphql) and they reference each other's types, use "multi" so cross-file references are validated.

Supported File Types

• .graphql
• .gql

Contributing

Found a bug? Have a feature idea? Contributions are welcome!

1. Fork the repo
2. Create a branch (git checkout -b my-feature)
3. Make your changes
4. Run tests (npm test)
5. Commit and push
6. Open a Pull Request

See CONTRIBUTING.md for detailed guidelines.

Development

npm install
npm run build
npm test        # 54 unit tests
# Press F5 in VS Code to launch Extension Development Host

License

MIT