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https://github.com/aerogear/graphql-metadata

Annotate your graphql schema with lightweight directives
https://github.com/aerogear/graphql-metadata

annotations graphql graphql-schema hacktoberfest

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Annotate your graphql schema with lightweight directives

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# graphql-metadata

Attach metadata to your GraphQL schema using directive like syntax.

Library supoports following formats:

- (**DEPRECATED**) Annotations: Group of elements with common namespace. For example `@db.length: 200`
- Marker: Single instance (key) with multiple values. For example `@db length:200`
- Metadata: Directive-like config. For example `@db(length: 200, columns: ['id', 'name'])`

## Installation

```bash
npm i graphql-metadata
```

## Usage

### Marker parsing

Markers using different syntax for elements that do not support grouping.
For example `@marker true` etc.

Usage:
```js
const result = parseMarker('db', `
This is a description
@db length:200, unique: true
`)
```

No value usage:

```js
const result = parseMarker('db', `
This is a description
@db
`)
```

### Metadata parsing

Metadata uses the same syntax as GraphQL directives.

Usage:

```js
const field: GraphQLField = {
...,
description: `@db(length:200,
unique: true,
columns: ['id', 'name']
description: 'Some description'
)`
}
const result = parseMetadata('db', field)

// Returns:
{
length:200,
unique: true,
columns: ['id', 'name']
description: 'Some description'
}
```

No value usage:

```js
const field: GraphQLField = {
...,
description: '@db',
}
const result = parseMetadata('db', field)

// Returns true
```

Or with a string:

```js
const result = parseMetadata('db', '@db(name: "users")')
```

### [DEPRECATED] Annotations parsing

Here is a very basic example with a `namespace` (here `'db'`) and a `description` that needs to be parsed:

```js
const { parseAnnotations } = require('graphql-metadata')

const result = parseAnnotations('db', `
This is a description
@db.length: 200
@db.foo: 'bar'
@db.unique
@db.index: { name: 'foo', type: 'string' }
`)

console.log(result)
```

This will output an object containing the annotations:

```js
{
length: 200,
foo: 'bar',
unique: true,
index: { name: 'foo', type: 'string' }
}
```

In a GraphQL schema, you can use the `description` property on `GraphQLObjectType`, `GraphQLField`...

```js
const { parseAnnotations } = require('graphql-metadata')
const { buildSchema, isObjectType } = require('graphql')

const schema = buildSchema(`
"""
@db.table: 'users'
"""
type User {
"""
@db.primary
"""
id: ID!
}
`)

const typeMap = schema.getTypeMap()
for (const key in typeMap) {
const type = typeMap[key]
// Tables
if (isObjectType(type)) {
const typeAnnotations = parseAnnotations('db', type.description)
console.log(type.name, typeAnnotations)
const fields = type.getFields()
for (const key in fields) {
const field = fields[key]
const fieldAnnotations = parseAnnotations('db', field.description)
console.log(field.name, fieldAnnotations)
}
}
}
```

Which will output:

```js
User { table: 'users' }
id { primary: true }
```

### Strip annotations

Sometimes it will be helpful to strip the annotations from the description. For example, you may not want to display them in a GraphQL schema explorer.

```js
const { stripAnnotations } = require('graphql-metadata')

const result = stripAnnotations('db', `
This is a description
@db.length: 200
@db.foo: 'bar'
@db.unique
@db.index: { name: 'foo', type: 'string' }
`)

console.log(result)
```

The result will be:

```js
`
This is a description
`
```