# graphile-utils

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This package contains helpers for building plugins for GraphQL schemas
utilising Graphile Engine, such as the one produced by
[PostGraphile](https://graphile.org/postgraphile).

Documentation is currently available
[here](https://graphile.org/postgraphile/extending/).

PRs to improve documentation are always welcome!

### `gql`

Similar to the default export from `graphql-tag`, this export can be used to
form tagged template literals that are useful when building schema
extensions. `gql` in `graphile-utils` differs from `graphql-tag` in a number
of ways, most notably: it can use interpolation to generate dynamically named
fields and types, and it can embed raw values using the `embed` helper.

### `embed`

Used to wrap a value to be included in a `gql` AST, e.g. for use in GraphQL
directives.

### `makeExtendSchemaPlugin`

Docs: https://www.graphile.org/postgraphile/make-extend-schema-plugin/

Enables you to add additonal types or extend existing types within your
Graphile Engine GraphQL schema.

```js
const {
  makeExtendSchemaPlugin,
  gql,
} = require('graphile-utils');

const MySchemaExtensionPlugin =
  makeExtendSchemaPlugin(
    build => ({
      typeDefs: gql`...`,
      resolvers: ...
    })
  );

module.exports = MySchemaExtensionPlugin;
```

e.g.:

```js
makeExtendSchemaPlugin(build => ({
  typeDefs: gql`
    type Random {
      float: Float!
      number(min: Int!, max: Int!): Int!
    }
    extend type Query {
      random: Random
    }
  `,
  resolvers: {
    Query: {
      random() {
        return {};
      },
    },
    Random: {
      float() {
        return Math.random();
      },
      number(_parent, { min, max }) {
        return min + Math.floor(Math.random() * (max - min + 1));
      },
    },
  },
}));
```

### `makeAddInflectorsPlugin`

Docs: https://www.graphile.org/postgraphile/make-add-inflectors-plugin/

If you don't like the default naming conventions that come with a Graphile
Engine GraphQL schema then it's easy for you to override them using the
inflector.

### `makeChangeNullabilityPlugin`

Docs: https://www.graphile.org/postgraphile/make-change-nullability-plugin/

Use this plugin to override the nullability of fields in your GraphQL schema.

### `makeProcessSchemaPlugin`

Docs: https://www.graphile.org/postgraphile/make-process-schema-plugin/

Enables you to process the schema after it's built, e.g. print it to a file,
augment it with a third party library (e.g. graphql-shield), etc.

### `makeWrapResolversPlugin`

Docs: https://www.graphile.org/postgraphile/make-wrap-resolvers-plugin/

Enables you to wrap the field resolvers in the generated GraphQL API,
allowing you to take an action before or after the resolver, or even modify
the resolver result.