JSON - object in array in object - how to parse through loop with JS?

Question

If I had this schema:

[{
    "Id": 2,
    "Prizes": [{
        "Id": 5,
        "Status": 0,
        "ClaimCode": "PN0016CXC1WPM64P",
        "User": {
            "FirstName": "John",
            "SecondName": "Doe",
        },
        "DrawId": 2,
        "PrizeId": 22,
        "Prize": null
    }]
}]

How could I get the first name or any value under object User that is in array prizes, that is in the main JSON?

I have tried this:

 const response = JSON.parse(this.responseText);
 response.Prizes[0].User.forEach(function(a) {
     output += `<li>${a.FirstName}</li>`;
 });

But getting the error undefined, I believe it can be extracted but only need right syntax. Or this can't be done with for loop?

response is an Array, not a plain Object. forEach should be used on an Array. — StackSlave
– StackSlave, Commented May 7, 2018 at 22:27
for(let key in response[0].Prizes[0].User), but I don't think you neeed a loop for this. — StackSlave
– StackSlave, Commented May 7, 2018 at 22:33
I have >1000 entries and I want to make a table so I believe I do need xD — Hotshot
– Hotshot, Commented May 7, 2018 at 22:39

Narendra Jadhav · Accepted Answer · 2018-05-08 17:39:11Z

1

First of all Response is an Array and User is an object, this should be working :

const response = JSON.parse(this.responseText);

response.map((resp) => {
    resp.Prizes.map((prize) => {
        output += `<li>${prize.User.FirstName}</li>`;

    })
})

edited May 8, 2018 at 17:39

Narendra Jadhav

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answered May 7, 2018 at 22:30

tjadli

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6 Comments

Hotshot Over a year ago

still returning Uncaught TypeError: Cannot read property '0' of undefined

tjadli Over a year ago

try it with loops added !

tjadli Over a year ago

Are you sure about the schema? Is it case sensitive?

Hotshot Over a year ago

100%sure I only remove some lines of info to shorten the code...it is case sensitive

tjadli Over a year ago

can u post a log of the response object ?

|

Ori Drori · Accepted Answer · 2018-05-07 22:31:01Z

0

Since you have an array of objects, and inside the object an array of values (Prizes), you can use nested Array.forEach() calls to get the internal values, wrap them with a string, and push to the items array:

const response = [{"Id":2,"Prizes":[{"Id":5,"Status":0,"ClaimCode":"PN0016CXC1WPM64P","User":{"FirstName":"John","SecondName":"Doe"},"DrawId":2,"PrizeId":22,"Prize":null}]}];

const items = [];

response.forEach((o) => 
  o.Prizes.forEach((p) =>
    items.push(`<li>${p.User.FirstName}</li>`)
  ));
  
list.innerHTML = items.join('');

<ul id="list"></ul>

answered May 7, 2018 at 22:31

Ori Drori

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Comments

Narendra Jadhav · Accepted Answer · 2018-05-08 17:37:02Z

0

As you have multidimensional array and you need to use Prizes as inside of array.

So first you can combine all Prizes into one using reduce() and the Spread_syntax then after you use map() with join mehod to get the required result.

DEMO

const response = [{"Id":2,"Prizes":[{"Id":5,"Status":0,"ClaimCode":"PN0016CXC1WPM64P","User":{"FirstName":"John","SecondName":"Doe"},"DrawId":2,"PrizeId":22,"Prize":null}]}];

let res = response.reduce((r,{Prizes}) =>[...r,...Prizes],[]).map(({User})=>`<li>${User.FirstName}</li>`).join('');

document.querySelector('ul').innerHTML =res ;

<ul></ul>

answered May 8, 2018 at 17:37

Narendra Jadhav

10.3k15 gold badges35 silver badges45 bronze badges

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