graphql-schema-from-json
Guess a GraphQL schema from json data.
Installation
npm install --save graphql-schema-from-json
or
yarn add graphql-schema-from-json
Usage
import getSchemaFromData from 'graphql-schema-from-json';
import { printSchema } from 'graphql';
const data = {
posts: [
{ id: 1, title: "Lorem Ipsum", views: 254, user_id: 123 },
{ id: 2, title: "Sic Dolor amet", views: 65, user_id: 456 },
],
users: [
{ id: 123, name: "John Doe" },
{ id: 456, name: "Jane Doe" }
],
comments: [
{ id: 987, post_id: 1, body: "Consectetur adipiscing elit", date: new Date('2017-07-03') },
{ id: 995, post_id: 1, body: "Nam molestie pellentesque dui", date: new Date('2017-08-17') }
]
}
// Get the schema as a JSON object
const schema = getSchemaFromData(data);
// Print the GQL for this schema
console.log(printSchema(schema));Generated Types and Queries
Based on your data, graphql-schema-from-json will generate a schema with one type per entity, as well as 3 query types and 3 mutation types. For instance for the Post entity:
type Query {
Post(id: ID!): Post
allPosts(page: Int, perPage: Int, sortField: String, sortOrder: String, filter: PostFilter): [Post]
_allPostsMeta(page: Int, perPage: Int, sortField: String, sortOrder: String, filter: PostFilter): ListMetadata
}
type Mutation {
createPost(data: String): Post
updatePost(data: String): Post
removePost(id: ID!): Boolean
}
type Post {
id: ID!
title: String!
views: Int!
user_id: ID!
User: User
Comments: [Comment]
}
type PostFilter {
q: String
id: ID
title: String
views: Int
views_lt: Int
views_lte: Int
views_gt: Int
views_gte: Int
user_id: ID
}
type ListMetadata {
count: Int!
}
scalar DateBy convention, graphql-schema-from-json expects all entities to have an id field that is unique for their type - it's the entity primary key. The type of every field is inferred from the values, so for instance, Post.title is a String!, and Post.views is an Int!. When all entities have a value for a field, graphql-schema-from-json makes the field type non nullable (that's why Post.views type is Int! and not Int).
For every field named *_id, graphql-schema-from-json creates a two-way relationship, to let you fetch related entities from both sides. For instance, the presence of the user_id field in the posts entity leads to the ability to fetch the related User for a Post - and the related Posts for a User.
The all* queries accept parameters to let you sort, paginate, and filter the list of results. You can filter by any field, not just the primary key. For instance, you can get the posts written by user 123. graphql-schema-from-json also adds a full-text query field named q, and created range filter fields for numeric and date fields. The detail of all available filters can be seen in the generated *Filter type.
GraphQL Usage
Here is how you can use the queries and mutations generated for your data, using Post as an example:
| Query / Mutation | Result |
|---|---|
// get a single entity, by id
{
Post(id: 1) {
id
title
views
user_id
}
}
|
{
"data": {
"Post": {
"id": 1,
"title": "Lorem Ipsum",
"views": 254,
"user_id": 123
}
}
}
|
// include many-to-one relationships
{
Post(id: 1) {
title
User {
name
}
}
}
|
{
"data": {
"Post": {
"title": "Lorem Ipsum",
"User": {
"name": "John Doe"
}
}
}
}
|
// include one-to-many relationships
{
Post(id: 1) {
title
Comments {
body
}
}
}
|
{
"data": {
"Post": {
"title": "Lorem Ipsum",
"Comments": [
{ "body": "Consectetur adipiscing elit" },
{ "body": "Nam molestie pellentesque dui" },
]
}
}
}
|
// get a list of entities for a type
{
allPosts {
title
views
}
}
|
{
"data": {
"allPosts": [
{ "title": "Lorem Ipsum", views: 254 },
{ "title": "Sic Dolor amet", views: 65 }
]
}
}
|
// paginate the results
{
allPosts(page: 0, perPage: 1) {
title
views
}
}
|
{
"data": {
"allPosts": [
{ "title": "Lorem Ipsum", views: 254 },
]
}
}
|
// sort the results by field
{
allPosts(sortField: "title", sortOrder: "desc") {
title
views
}
}
|
{
"data": {
"allPosts": [
{ "title": "Sic Dolor amet", views: 65 }
{ "title": "Lorem Ipsum", views: 254 },
]
}
}
|
// filter the results using the full-text filter
{
allPosts({ filter: { q: "lorem" }}) {
title
views
}
}
|
{
"data": {
"allPosts": [
{ "title": "Lorem Ipsum", views: 254 },
]
}
}
|
// filter the result using any of the entity fields
{
allPosts(views: 254) {
title
views
}
}
|
{
"data": {
"allPosts": [
{ "title": "Lorem Ipsum", views: 254 },
]
}
}
|
// number fields get range filters
// -lt, _lte, -gt, and _gte
{
allPosts(views_gte: 200) {
title
views
}
}
|
{
"data": {
"allPosts": [
{ "title": "Lorem Ipsum", views: 254 },
]
}
}
|
Roadmap
- Allow to override the primary key for each entity
- Allow to override the relationship detection
Contributing
Use Prettier formatting and make sure you include unit tests. The project includes a Makefile to automate usual developer tasks:
make install
make build
make test
make watch
make formatLicense
graphql-schema-from-json is licensed under the MIT Licence, sponsored and supported by marmelab.