walmartlabs / json-to-simple-graphql-schema

Transforms JSON input into a GraphQL schema

json-to-simple-graphql-schema

Transforms JSON input into a GraphQL schema. Try it here

Why would I use this?

Let's say you want to use an existing REST API in a GraphQL service and expose the data that API provides. You'll need to expose that data in a GraphQL schema. Without this tool, you'll have to slog through the JSON response and manually extract and convert the relevant types to GraphQL schema types. This tool attempts to provide an automated reasonable first-pass at that effort.

Installation:

For use as a command-line app use npx :) If you'd really like to install, you can do:

npm i -g @walmartlabs/json-to-simple-graphql-schema

For use in a project:

npm i @walmartlabs/json-to-simple-graphql-schema

Command Line Usage:

Pipe in some JSON. Here's a cURL JSON response piped in to this app:

curl "https://data.cityofnewyork.us/api/views/kku6-nxdu/rows.json?accessType=DOWNLOAD" \
| npx @walmartlabs/json-to-simple-graphql-schema

You'll still need to rename the resulting main Type in the schema, unless you like AutogeneratedMainType :)

Or pipe in some JSON from a JSON file.

curl https://data.cityofnewyork.us/api/views/kku6-nxdu/rows.json?accessType=DOWNLOAD > input.json

cat input.json | npx json-to-simple-graphql-schema > output.graphql

Optional parameters:

• baseType = "AutogeneratedMainType"
• prefix = ""

curl https://data.cityofnewyork.us/api/views/kku6-nxdu/rows.json?accessType=DOWNLOAD > input.json

cat input.json | npx json-to-simple-graphql-schema --baseType BaseType --prefix Prefix > output.graphql

Usage in front-end JS:

import { jsonToSchema } from "@walmartlabs/json-to-simple-graphql-schema/lib";

const schema = jsonToSchema({ jsonInput: '{"name": "Test"}' });
console.log(schema.value);

If you need more guidance, have a look at the source for our simple web-ui.

Example output:

Given this JSON:

{
  "id": "some-id-0",
  "name": "A fun object",
  "subType": {
    "id": "some-id-1",
    "name": "A fun sub-type"
  }
}

This app will send this to stdout:

type SubType {
  id: String
  name: String,
}
type AutogeneratedMainType {
  id: String
  name: String
  subType: SubType
}

Fun features: duplicate removal

Consider this JSON with 2 color types:

{
  "id": "some-id-0",
  "name": "A fun object",
  "color": {
    "id": "color-id-1",
    "name": "Test color"
  },
  "subType": {
    "id": "some-id-1",
    "name": "A fun sub-type",
    "color": {
      "id": "color-id-1",
      "name": "Test color",
      "hex": "#ff0000"
    }
  }
}

When piped to this app, the following schema is produced:

type Color {
  id: String
  name: String
  hex: String,
}
type SubType {
  id: String
  name: String
  color: Color,
}
type AutogeneratedMainType {
  id: String
  name: String
  subType: SubType
  color: Color
}

It kept the Color type with more fields.

Fun features: calls out possible duplicates

Consider this JSON with two types containing identical fields:

{
  "id": "some-id-0",
  "name": "A fun object",
  "color": {
    "id": "color-id-1",
    "name": "Test color"
  },
  "favoriteColor": {
    "id": "color-id-1",
    "name": "Test color"
  }
}

When piped to this app, the following schema is produced:

type FavoriteColor {
  id: String
  name: String
}

type Color {
  id: String
  name: String
}

type AutogeneratedMainType {
  id: String
  name: String
  favoriteColor: FavoriteColor
  color: Color
}

# Types with identical fields:
# FavoriteColor Color

It called out the two types with identical fields.

json-to-simple-graphql-schema's Issues

Adding an option "prefix" for Type object names

I'd like to append/merge differerent schemas generated by this tool. It would be useful to be able to create all new Type objects with a prefix string in order to not create conflicts with other schemas...

Is it possible to implement it?

Thanks in advance
Matteo

ability to assign custom data types for named fields

For instance, I'm using this tool to create a graphQL schema for use with AWS Amplify, and I would like to be able to specify all fields named createdAt with a custom data type AWSDateTime. Something like --type createdAt AWSDateTime would be useful.

some character that are not supported by graphql to be shown as any object

When we have the following data, it was not represented correctly.
For example,

    "exclude": {
      "**/.hg": true,
      "**/CVS": true,
      "**/.git": true,
      "**/.svn": true,
      "**/.DS_Store": true
    },

gets converted to

Current output

type  { hg: Boolean
  git: Boolean
  svn: Boolean
  DS_Store: Boolean }

type Exclude { **/:  **/CVS: Boolean }

Expected to be AnyObject or JSONObject

Invalid typeDefs created if json key contains string `type` at end of string

Firstly, nice little tool - thanks!

I think there's a small bug in the key name matching/splitting, where if a key in the source json has the string type at the end of it, then it's split like it's a new type definition in the output.

Example: (This causes an error in types, but doesn't throw an error in the tool)

const test = {
  "atype": {
    "here": "Now"
  }
}

results incorrectly in

type A

type {
  here: String
}

type RootTypeName {
  atype: Atype
}

---

If the source json had camelcased or similar, it seems to work ok.

Example: (This works ok)

const test = {
  "aType": {
    "here": "Now"
  }
}

Outputs correctly:

type AType {
  here: String
}

type Main {
  aType: AType
}

how can i use description for schema

i need to add description for this param
how to set

Change main type name of result

Is there a way or are you just considering telling the function how to name the main type instead of AutogeneratedMainType?

Something like:

const json = { jsonInput: '{"name": "Test"}' }
const schema = jsonToSchema("useThisMainTypeName", json);

Add gh pages to readme or so

Just fyi ... I have activated the ghpages off the docs folder. As requested...

https://walmartlabs.github.io/json-to-simple-graphql-schema/

you probably want to add it to the readme or so.

question: does node have to be set at 10+

Is it possible to downgrade the supported node engine down to LTS or is 10.0.0 a requirement?

Large JSON file appears to have issue processing.

Is there a limit on the size of JSON file we can provide?

make a simple webapp to use this on the browser

Please consider hosting a simple webapp to paste the json and get the schema back so one-time users don't have to download the lib from npm

Arrays does not produce valid Schema

Given this following JSON,

{
  "name": "Example.com",
  "data": [
    {
      "Property 1": "Example.com",
      "Property 3": "Something else"
    },
    {
      "Property 2": "Something else"
    },
    {
      "Property 2": "Something else",
      "Property 3": "Something else"
    }
  ]
}

This is the output,

type Data { Property1: String Property3: String }

type AutogeneratedMainType { name: String data: [Data ] }

Property2 is omitted and there is a Property3 instead.