GraphQL processing array json data

Question

I am new to GraphQL and not really sure if this problem is my lack of JavaScript knowledge or GraphQL.

My GraphQL queries an external service and when the response is a scalar json object everything works great. The problem comes when the external service returns an array of json.

This works for a single json result:

const transform = (json) => {
  return {
    id: json.id,
    fullname: json.fullName,
    email: json.email
}

But for an array like this the mapping code is inadequate.

[{id:...fullname:...email:...},{id:...etc},{id:...etc}]

Now I can detect that the return is an array and I can loop through the array just not sure how to map into a GraphQLList.

So after Googling I found GraphQLList but it doesn't work either.

...snip from Schema...
UserData: {
        type: GraphQLLIst(UserType),

same mapping code as above.

message": "Expected Iterable, but did not find one for field RootQueryType.investorData.

But I'm confused because the console log clearly shows a json array?

GraphQLSchema

const RootQueryType = new GraphQLObjectType({
   name: 'RootQueryType',
   fields:{
    investorData: {
        type: new GraphQLList(UserType),
        description: 'Get investors by id',
        args:{key: {type: GraphQLString} },
        resolve: resolveInvestorData
       }
     }
   }
})

Could you post your GraphQL schema? What is the type you defined for investorData field? — Yevhenii Herasymchuk
– Yevhenii Herasymchuk, Commented Jan 27, 2019 at 12:23

GPGVM · Accepted Answer · 2019-01-27 23:32:23Z

Problem is solved but not by any genius on my part but rather dumb luck.

So by adding mapping code I am actually interfering with GraphQL's mapping.

This is wrong but posted here for before and after comparison.

GraphQLSchema:

const RootQueryType = new GraphQLObjectType({ name: 'RootQueryType',

fields: {    
    userData: {
        type: new GraphQLList(UserType),
        args:{key: {type: GraphQLString} },
        resolve: resolveUserData
       }
    }
  }
})

ResolveUserData:

return fetch(url)
   .then(response => {
      return response.json()
      })
   .then(json => {
      return transformUser(json)
      })
   .catch(err => {
      console.trace(err)
     })  
  }

const transformUser = (json) => {
  console.trace(json);
  return {
    id: json.id,
    portfolioid: json.portfolioID,
    fullname: json.fullName,
    email: json.email
   }
}

Correct returned data mapping. (Hint NO MAPPING)

return fetch(url)
   .then(response => {
      return response.json()
      })
   .catch(err => {
      console.trace(err)
     })  
  }

Now this is MY final solution as I wanted one endpoint to handle both a single lookup and a "Get All" request. Feel free to comment on this architecture.

const resolveUserData = (obj, args) => {

let url = '';

//if branch to determine if one user or all
if (typeof args.key === "undefined") {
    url = 'http://localhost:5001/api/users';
}
else
{
    url = 'http://localhost:5001/api/users/' + args.key;
}

return fetch(url)
.then(response => {
  return response.json()
})
.then(json => {
    if(!Array.isArray(json))
    {
        var jarray = [];
        jarray.push(json);
        return jarray;
    }
    return json
})
.catch(err => {
  console.trace(err)
})

}

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