GraphQL Schema to JSON Schema 
graphql-2-json-schema package
Transform a GraphQL Schema introspection file to a valid JSON Schema.
Usage
import {
graphqlSync,
getIntrospectionQuery,
IntrospectionQuery
} from 'graphql';
import { fromIntrospectionQuery } from 'graphql-2-json-schema';
const options = {
// Whether or not to ignore GraphQL internals that are probably not relevant
// to documentation generation.
// Defaults to `true`
ignoreInternals: true,
// Whether or not to properly represent GraphQL Lists with Nullable elements
// as type "array" with items being an "anyOf" that includes the possible
// type and a "null" type.
// Defaults to `false` for backwards compatibility, but in future versions
// the effect of `true` is likely going to be the default and only way. It is
// highly recommended that new implementations set this value to `true`.
nullableArrayItems: true,
// Indicates how to define the `ID` scalar as part of a JSON Schema. Valid options
// are `string`, `number`, or `both`. Defaults to `string`
idTypeMapping: 'string'
}
// schema is your GraphQL schema.
const introspection = graphqlSync(schema, getIntrospectionQuery()).data as IntrospectionQuery;
const jsonSchema = fromIntrospectionQuery(introspection, options);Example
Input
type Todo {
id: ID!
name: String!
completed: Boolean
color: Color
"A field that requires an argument"
colors(
filter: [Color!]!
): [Color!]!
}
type SimpleTodo {
id: ID!
name: String!
}
union TodoUnion = Todo | SimpleTodo
input TodoInputType {
name: String!
completed: Boolean
color: Color=RED
}
enum Color {
"Red color"
RED
"Green color"
GREEN
}
type Query {
"A Query with 1 required argument and 1 optional argument"
todo(
id: ID!,
"A default value of false"
isCompleted: Boolean=false
): Todo
"Returns a list (or null) that can contain null values"
todos(
"Required argument that is a list that cannot contain null values"
ids: [String!]!
): [Todo]
}
type Mutation {
"A Mutation with 1 required argument"
create_todo(
todo: TodoInputType!
): Todo!
"A Mutation with 2 required arguments"
update_todo(
id: ID!,
data: TodoInputType!
): Todo!
"Returns a list (or null) that can contain null values"
update_todos(
ids: [String!]!
data: TodoInputType!
): [Todo]
}Output
// Output is from call to fromIntrospectionQuery with the following options:
const options = { nullableArrayItems: true }
{
'$schema': 'http://json-schema.org/draft-06/schema#',
properties: {
Query: {
type: 'object',
properties: {
todo: {
description: 'A Query with 1 required argument and 1 optional argument',
type: 'object',
properties: {
return: { '$ref': '#/definitions/Todo' },
arguments: {
type: 'object',
properties: {
id: { '$ref': '#/definitions/ID' },
isCompleted: {
description: 'A default value of false',
'$ref': '#/definitions/Boolean',
default: false
}
},
required: [ 'id' ]
}
},
required: []
},
todos: {
description: 'Returns a list (or null) that can contain null values',
type: 'object',
properties: {
return: {
type: 'array',
items: {
anyOf: [ { '$ref': '#/definitions/Todo' }, { type: 'null' } ]
}
},
arguments: {
type: 'object',
properties: {
ids: {
description: 'Required argument that is a list that cannot contain null values',
type: 'array',
items: { '$ref': '#/definitions/String' }
}
},
required: [ 'ids' ]
}
},
required: []
}
},
required: []
},
Mutation: {
type: 'object',
properties: {
create_todo: {
description: 'A Mutation with 1 required argument',
type: 'object',
properties: {
return: { '$ref': '#/definitions/Todo' },
arguments: {
type: 'object',
properties: { todo: { '$ref': '#/definitions/TodoInputType' } },
required: [ 'todo' ]
}
},
required: []
},
update_todo: {
description: 'A Mutation with 2 required arguments',
type: 'object',
properties: {
return: { '$ref': '#/definitions/Todo' },
arguments: {
type: 'object',
properties: {
id: { '$ref': '#/definitions/ID' },
data: { '$ref': '#/definitions/TodoInputType' }
},
required: [ 'id', 'data' ]
}
},
required: []
},
update_todos: {
description: 'Returns a list (or null) that can contain null values',
type: 'object',
properties: {
return: {
type: 'array',
items: {
anyOf: [ { '$ref': '#/definitions/Todo' }, { type: 'null' } ]
}
},
arguments: {
type: 'object',
properties: {
ids: {
type: 'array',
items: { '$ref': '#/definitions/String' }
},
data: { '$ref': '#/definitions/TodoInputType' }
},
required: [ 'ids', 'data' ]
}
},
required: []
}
},
required: []
}
},
definitions: {
Todo: {
type: 'object',
properties: {
id: {
type: 'object',
properties: {
return: { '$ref': '#/definitions/ID' },
arguments: { type: 'object', properties: {}, required: [] }
},
required: []
},
name: {
type: 'object',
properties: {
return: { '$ref': '#/definitions/String' },
arguments: { type: 'object', properties: {}, required: [] }
},
required: []
},
completed: {
type: 'object',
properties: {
return: { '$ref': '#/definitions/Boolean' },
arguments: { type: 'object', properties: {}, required: [] }
},
required: []
},
color: {
type: 'object',
properties: {
return: { '$ref': '#/definitions/Color' },
arguments: { type: 'object', properties: {}, required: [] }
},
required: []
},
colors: {
description: 'A field that requires an argument',
type: 'object',
properties: {
return: { type: 'array', items: { '$ref': '#/definitions/Color' } },
arguments: {
type: 'object',
properties: {
filter: {
type: 'array',
items: { '$ref': '#/definitions/Color' }
}
},
required: [ 'filter' ]
}
},
required: []
}
},
required: [ 'id', 'name', 'colors' ]
},
ID: {
description: 'The `ID` scalar type represents a unique identifier, often used to refetch an object or as key for a cache. The ID type appears in a JSON response as a String; however, it is not intended to be human-readable. When expected as an input type, any string (such as `"4"`) or integer (such as `4`) input value will be accepted as an ID.',
type: 'string',
title: 'ID'
},
SimpleTodo: {
type: 'object',
properties: {
id: {
type: 'object',
properties: {
return: { '$ref': '#/definitions/ID' },
arguments: { type: 'object', properties: {}, required: [] }
},
required: []
},
name: {
type: 'object',
properties: {
return: { '$ref': '#/definitions/String' },
arguments: { type: 'object', properties: {}, required: [] }
},
required: []
}
},
required: [ 'id', 'name' ]
},
TodoUnion: {
oneOf: [
{ '$ref': '#/definitions/Todo' },
{ '$ref': '#/definitions/SimpleTodo' }
]
},
TodoInputType: {
type: 'object',
properties: {
name: { '$ref': '#/definitions/String' },
completed: { '$ref': '#/definitions/Boolean' },
color: { '$ref': '#/definitions/Color', default: 'RED' }
},
required: [ 'name' ]
},
Color: {
type: 'string',
anyOf: [
{
description: 'Red color',
enum: [ 'RED' ],
title: 'Red color'
},
{
description: 'Green color',
enum: [ 'GREEN' ],
title: 'Green color'
}
]
},
String: {
description: 'The `String` scalar type represents textual data, represented as UTF-8 character sequences. The String type is most often used by GraphQL to represent free-form human-readable text.',
type: 'string',
title: 'String'
},
Boolean: {
description: 'The `Boolean` scalar type represents `true` or `false`.',
type: 'boolean',
title: 'Boolean'
}
}
}