Graphql nested query issue using node.js-CodePudding

Hi noobie to graphql ive created a simple node.js project that communicates with apollo Server. The issues is that i want to nest comments that relate to each product. As you can see ive added productId in both types.

below in Apollo Explorer i want to run the below query to nest comment relating to each product my plan is store each products and comments in seperates db tables eventually.

query {

    allProducts {
      product_Description
      comment {
        commentBody
      }
    }
  }


const { ApolloServer, gql } = require('apollo-server')



let products = [
    {
        productId : 101,
        productTitle : "EasyJet Summer Flight Sale 2023 - 100,000 flights on offer - From £29.99",
        product_Description : " cheaps flights available",
        price : "£302",
    },
    {
        productId : 102,
        productTitle : "Apple Leather Case with MagSafe for iPhone 13 Pro Max  Midnight",
        product_Description : "Aple leather case get this deal!!!",
        price : "£29"
    },
    {
        productId : 103,
        productTitle : "Xiaomi Redmi Note 10 Pro - Mobile Phone 6 128 GB",
        product_Description : "Another chinese mobile phone yarn !!!",
        price : "£120"
    }
]

let comments = [
    {
        commentId   : 1,
        commentBody : "amazing product really cheap flights",
        productId : 101,
    },
    {
        commentId   : 2,
        commentBody : "amazing product really cheap flights",
        productId : 102,
    },
    {
        commentId   : "3",
        commentBody : "amazing product really cheap flights",
        productId : 103,
    },
]


const typeDefs = gql  `

type Product {
    productId: ID!,
    productTitle: String!,
    product_Description: String!,
    price: String!
    comment: [Comment]
}

type Comment {
    commentId: Int!,
    commentBody: String!,
}

type Query {
    productCount: Int!
    allProducts: [Product!]!
    allComments: [Comment!]!
    findProduct(productTitle: String!): Product
}
`

const resolvers = {
    Query: {
        productCount: () => products.length,
        allProducts: () => products,
        allComments: () => comments,
        findProduct: (root, args) => products.find(p => p.productTitle === args.productTitle),
    },
    Product: {
        comment: parent => {
            console.log('parent data',parent)
            return parent.comment.map(commentList => parent.productId === commentList.productId)
        }
    }
}


const server = new ApolloServer({
    typeDefs,
    resolvers,
  })
  
  server.listen().then(({ url }) => {
    console.log(`Server ready at ${url}`)
  })

this is error im getting

{
  "errors": [
    {
      "message": "Cannot return null for non-nullable field Comment.commentId.",
      "locations": [
        {
          "line": 6,
          "column": 9

any help greatfully appreciated :)

CodePudding user response：

You're mapping when you should be filtering. Also your comments aren't attached to the parent, they are just a variable in scope.

Change:

return parent.comment.map(
  commentList => parent.productId === commentList.productId
)

to:

return comments.filter(
  el => parent.productId === el.productId
)