Node GraphQL resolve null data from API

Question

I am learning GraphQL through their official website.

The purpose of my graphql on this code is as wrapper for my existing REST API. To do that, i already have a rest api with this response:

GET: /people/:id
RESPONSE: 
{
  "person": [
    {
      "id": "1",
      "userName": "mark1",
      "firstName": "Mark",
      "lastName": "Zuckerberg",
      "email": "mark@facebook.com",
      "friends": [
        "/people/2",
        "/people/3"
      ]
    }
  ]
}

and this following code is my graphql schema

import {
    GraphQLList,
    GraphQLObjectType,
    GraphQLString,
    GraphQLSchema
} from "graphql";

import fetch from "node-fetch";

const BASE_URL = "http://localhost:5000";

function getPersonByURL(relativeUrl) {
    return fetch(`${BASE_URL}${relativeUrl}`)
        .then(res => res.json())
        .then(json => json.person);
}

const PersonType = new GraphQLObjectType({
    name: "Person",
    type: "Somebody",
    fields: () => ({
        firstName: {
            type: GraphQLString,
            resolve: person => person.firstName
        },
        lastName: {
            type: GraphQLString,
            resolve: person => person.lastName
        },
        email: {
            type: GraphQLString
        },
        id: {
            type: GraphQLString
        },
        userName: {
            type: GraphQLString
        },
        friends: {
            type: new GraphQLList(PersonType),
            resolve: (person) => person.friends.map(getPersonByURL)
        }
    })
});

const QueryType = new GraphQLObjectType({
    name: "Query",
    description: "the root of all queries",
    fields: () => ({
        person: {
            type: PersonType,
            args: {
                id: { type: GraphQLString }
            },
            resolve: (root, args) => getPersonByURL(`/people/${args.id}`)
        }
    })
});

export default new GraphQLSchema({
    query: QueryType
});

when i execute a request using Graphiql it returned null on each field. I believe i made mistake on how i represent my json response or how i accesing my json response from rest api.

These are the request and the result from graphiql

REQUEST
{
  person(id: "1") {
    firstName
  }
}

RESPONSE
{
  "data": {
    "person": {
      "firstName": null
    }
  }
}

Can you please help with any hint?

score 1 · Accepted Answer · answered May 27 '17 at 14:12

To find the issue I have put your json to gist and modified your code as bellow:

// ...
firstName: {
  type: GraphQLString,
  resolve: person => JSON.stringify(person)
},
// ...

After running the following query:

{
  person(id: "1") {
    firstName
  }
}

here was the result:

{
"data": {
    "person": {
      "firstName": "[{\"id\":\"1\",\"userName\":\"mark1\",\"firstName\":\"Mark\",\"lastName\":\"Zuckerberg\",\"email\":\"mark@facebook.com\",\"friends\":[\"/people/2\",\"/people/3\"]}]"
    }
  }
}

You can notice that person is an array so obviously it doesn't have firstName and other properties. You have to unwrap array either in each field resolver or in the root type resolver:

resolve: (root, args) => getPersonByURL(`/people${args.id}.json`)
  .then(persons => persons[0])

Here is GraphQL Launchpad with working code: https://launchpad.graphql.com/j1v0kprrp

yes that is the answer, thank you for the help – lloistborn May 27 '17 at 14:18 — lloistborn, May 27 '17 at 14:18

Node GraphQL resolve null data from API

1 Answers1