Getting Started

Installation

Start by installing the plugin package, which includes everything you need:

npm i -D @graphql-eslint/eslint-plugin

Configuration

To get started, define an override in your ESLint config to apply this plugin to .graphql files. Add the rules you want applied.

{
  "overrides": [
    {
      "files": ["*.graphql"],
      "parser": "@graphql-eslint/eslint-plugin",
      "plugins": ["@graphql-eslint"],
      "rules": {
        "@graphql-eslint/known-type-names": "error"
      }
    }
  ]
}

If your GraphQL definitions are defined only in .graphql files, and you’re only using rules that apply to individual files, you should be good to go 👍. If you would like use a remote schema or use rules that apply across the entire collection of definitions at once, see here.

Apply Plugin to GraphQL Definitions Defined in Code Files

If you are defining GraphQL schema or GraphQL operations in code files, you’ll want to define an additional override to extend the functionality of this plugin to the schema and operations in those files.

{
  "overrides": [
+   {
+     "files": ["*.js"],
+     "processor": "@graphql-eslint/graphql"
+   },
    {
      "files": ["*.graphql"],
      "parser": "@graphql-eslint/eslint-plugin",
      "plugins": ["@graphql-eslint"],
      "rules": {
        "@graphql-eslint/known-type-names": "error"
      }
    }
  ]
}

Under the hood, specifying the @graphql-eslint/graphql processor for code files will cause graphql-eslint/graphql to extract the schema and operation definitions from these files into virtual GraphQL documents with .graphql extensions. This will allow the overrides you’ve defined for .graphql files, via "files": ["*.graphql"], to get applied to the definitions defined in your code files.

Extended Linting Rules with GraphQL Schema

Some rules require an understanding of the entire schema at once. For example, no-unreachable-types checks that all types are reachable by root-level fields.

To use these rules, you’ll need to tell ESLint how to identify the entire set of schema definitions.

If you are using graphql-config, you are good to go. graphql-eslint integrates with it automatically and will use it to load your schema!

Alternatively, you can define parserOptions.schema in the *.graphql override in your ESLint config.

The parser allows you to specify a json file / graphql files(s) / url / raw string to locate your schema (We are using graphql-tools to do that). Just add parserOptions.schema to your configuration file:

{
  "files": ["*.graphql"],
  "parser": "@graphql-eslint/eslint-plugin",
  "plugins": ["@graphql-eslint"],
  "rules": {
    "@graphql-eslint/no-unreachable-types": "error"
  },
+ "parserOptions": {
+   "schema": "./schema.graphql"
+ }
}

You can find a complete documentation of the parserOptions here.

Some rules require type information to operate, it’s marked in the docs for each rule!

Extended Linting Rules with Siblings Operations

While implementing this tool, we had to find solutions for a better integration of the GraphQL ecosystem and ESLint core.

GraphQL’s operations can be distributed across many files, while ESLint operates on one file at a time. If you are using GraphQL fragments in separate files, some rules might yield incorrect results, due the missing information.

To workaround that, we allow you to provide additional information on your GraphQL operations, making it available for rules while doing the actual linting.

To provide that, we are using graphql-tools loaders to load your sibling operations and fragments, just specify a glob expression(s) that points to your code/.graphql files:

{
  "files": ["*.graphql"],
  "parser": "@graphql-eslint/eslint-plugin",
  "plugins": ["@graphql-eslint"],
  "rules": {
    "@graphql-eslint/unique-operation-name": "error"
  },
  "parserOptions": {
+   "operations": "./src/**/*.graphql",
    "schema": "./schema.graphql"
  }
}

Disabling Rules

The graphql-eslint parser looks for GraphQL comments syntax (marked with #) and will send it to ESLint as directives. That means, you can use ESLint directives syntax to hint ESLint, just like in any other type of files.

To disable ESLint for a specific line, you can do:

# eslint-disable-next-line
type Query {
  foo: String!
}

You can also specify specific rules to disable, apply it over the entire file, eslint-disable-next-line or current eslint-disable-line.

You can find a list of ESLint directives here.

VSCode Integration

Use ESLint VSCode extension to integrate ESLint into VSCode.

For syntax highlighting you need a GraphQL extension (which may potentially have its own linting), for example GraphQL (by GraphQL Foundation).

Further Reading

If you wish to learn more about this project, how the parser works, how to add custom rules and more please refer to the below links:

• Writing Custom Rules
• How the parser works?
• parserOptions