Can't Use MAP data structure in Node.js

Question

I have getting some issue in map program in node.js. I am trying to use MAP into node.js program and I am not getting value.I have write some code to use map however I think it not working as its not go into the loop to fetch the key-value.

Please find below program

  async CreateProduceMVPRateAsset(data, callback) {

     var ProducePRICE = {};

             var MVPPRICE =[];
             var MVPPRICE_BS ={};
             var MVPPRICE_LB ={};
             //var ASKINGPRICE= {}// put all the things which need to go to blockchain
            const walletPath = path.join(process.cwd(), 'wallet');
            const wallet = new FileSystemWallet(walletPath);
            console.log(`Wallet path: ${walletPath}`);
            console.log('Data', data);
            console.log('Username', data.username);

 var PRODUCENAME = data.PRODUCE
            console.log('PRODUCENAME', PRODUCENAME);

            var COUNTRY = data.COUNTRY;
            console.log('COUNTRY', COUNTRY);
            var STATE = data.STATE;
            console.log('STATE', STATE);


          var MVPRATES =  data.MVPRATES;  

             console.log('MVPRATERATE', MVPRATES);

             const MVPRATE = new Map(MVPRATES);

// program could not go inside the for loop
             for (const [k, v] of MVPRATE.entries()) {
                 console.log("Inside map", k, v)
                 MVPPRICE = v.RATE  // should go in  MVPPRICE 

                  var Value =  MVPPRICE[0].value // want to get first element value from MVPPRICE array 
                  console.log('Value', Value);

                 var value_lb = Value/40;
                 console.log('value_lb', value_lb);

                 value_lb = Number((value_lb).toFixed(4));

                    console.log('If the value of BS provided controller come here');

                    MVPPRICE_LB.Value = value_lb
                    MVPPRICE_LB.QuantityUnit = 'LB'
                    MVPPRICE_LB.uidisplay = false
                    MVPPRICE_LB.CurrencyUnit = 'USD'

                    MVPPRICE.push(MVPPRICE_LB);
                    ProducePRICE.MVPPRICE = MVPPRICE

                        console.log('MVPPRICE',MVPPRICE);
                   console.log('ProducePRICE',ProducePRICE);

                    // mvpprice.totalPrice = totalPrice;
                    console.log('for pricing',totalPrice);

                    // ProducePRICE.VARIETY = VARIETY;
                    ProducePRICE.PRODUCENAME = PRODUCENAME;
                    ProducePRICE.STATE = STATE;
                    ProducePRICE.COUNTRY = COUNTRY;

              }

JSON structure which I am sending using postman

{
"username": "admin2",
  "PRODUCE": "Apple",
  "STATE": "MI",
  "COUNTRY": "US",
  "MVPRATES": {
    "fuji": {
      "VARIETY": "fuji",
      "RATE": [
        {
          "UNIT": "Bussel",
          "CURRENCY": "USD",
          "VALUE": 10.25,
          "UIDISPLAY": true
        }
      ]
    },
    "gala": {
      "VARIETY": "gala",
      "RATE": [
        {
          "UNIT": "Bussel",
          "CURRENCY": "USD",
          "VALUE": 10.25,
          "UIDISPLAY": true
        }
      ]
    }
  }
}

Output which I am getting:

odd you don't get an error TypeError: object is not iterable considering data.MVPRATES is not iterable — Bravo
– Bravo, Commented Oct 7, 2019 at 9:09
@ Bravo I don't get this error as its not go inside the loop I think — Abhirocks
– Abhirocks, Commented Oct 7, 2019 at 9:11
Oh, the error should come from const MVPRATE = new Map(MVPRATES); ... before the loop - are you calling CreateProduceMVPRateAsset in a try/catch perhaps, and ignoring the error? and why is CreateProduceMVPRateAsset declared async since a) it doesn't do any await and b) there is no reason for it to be asynchronouos — Bravo
– Bravo, Commented Oct 7, 2019 at 9:12
Ok @ I made it like const MVPRATE = new Map(); It run but still its not go inside the for loop and skip the loop . — Abhirocks
– Abhirocks, Commented Oct 7, 2019 at 9:15
of course, because the Map is empty, therefore nothing to iterate - what is the purpose of using Map? new toy? or is there a particular reason you want to do that? — Bravo
– Bravo, Commented Oct 7, 2019 at 9:16

Bravo · Accepted Answer · 2019-10-07 09:22:07Z

1

Seems like you may want to do the following, this creates a Map with two entries, fuji and gala

const MVPRATES = {
  "fuji": {
    "VARIETY": "fuji",
    "RATE": [{
      "UNIT": "Bussel",
      "CURRENCY": "USD",
      "VALUE": 10.25,
      "UIDISPLAY": true
    }]
  },
  "gala": {
    "VARIETY": "gala",
    "RATE": [{
      "UNIT": "Bussel",
      "CURRENCY": "USD",
      "VALUE": 10.25,
      "UIDISPLAY": true
    }]
  }
}
const MVPRATE = new Map(Object.entries(MVPRATES));
for (const [k, v] of MVPRATE.entries()) {
  console.log("Inside map", k, v)
}

Though, the need for Map is still unclear, as you can achieve the above with

const MVPRATES = {
  "fuji": {
    "VARIETY": "fuji",
    "RATE": [{
      "UNIT": "Bussel",
      "CURRENCY": "USD",
      "VALUE": 10.25,
      "UIDISPLAY": true
    }]
  },
  "gala": {
    "VARIETY": "gala",
    "RATE": [{
      "UNIT": "Bussel",
      "CURRENCY": "USD",
      "VALUE": 10.25,
      "UIDISPLAY": true
    }]
  }
}
for (const [k, v] of Object.entries(MVPRATES)) {
  console.log("Inside map", k, v)
}

answered Oct 7, 2019 at 9:22

Bravo

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3 Comments

Abhirocks Over a year ago

Thanks soo much @ Bravo I have to check with my need, however your solution helpful

Abhirocks Over a year ago

Hi @ Bravo I have small issue here , I have used var Value = MVPPRICE[0].value, which is give undefined could you please suggest me why? if possible

Bravo Over a year ago

oh ... becauase value is not VALUE as they are two different things (javascript is case sensitive)

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