CODEWITHSUNDEEP
javascriptjsonnode.js
Amanda G
Amanda G

Reputation: 1981

Passing a external variable in JSON.parse function

I am trying to get a value from json by using the JSON.parse function. My json response is given below:

{
  "rows": 10,
  "os": "0",
  "page": "1",
  "total": "122",
  "projects": {
    "P143841": {
      "id": "P143841",
      "locations": [{
        "geoLocId": "0002220957",
        "latitude": "3.866667",
        "longitude": "11.516667"
      }],
    }
  }
}

I am able to get the value 10 if I do JSON.parse(obj.rows) but if I assign the rows to a variable say var value = rows and then I pass it to the JSON.parse(obj.value) function I got undefined.

P.S. I won't be knowing the names of the response parameters, i.e. i won't know if it will be rows or os quoting from the above example. I will be retrieving them from a database. If I perform the code below:

  for (var i=0;i<length;i++) {
    var value = responseParam_array[i];
    console.log(obj.value);
  }

I get the output but any help will be much appreciated.

Upvotes: 4

Views: 16214

Answers (3)

nnnnnn
nnnnnn

Reputation: 150070

As per the other answers you shouldn't need to parse individual properties, just parse the original JSON and then operate on the resulting object.

But as for this problem:

"if I assign the rows to a variable say var value = rows and then I pass it to the JSON.parse(obj.value) function I got undefined"

If value is a variable holding the name of a property of obj then you need:

obj[value]
// NOT
obj.value

When you use "dot" notation the part on the right of the dot is taken as the literal name of the property, not as a variable. Using the square-bracket syntax the expression in the brackets is evaluated and its result is taken as the property name.

Upvotes: 6

hunterloftis
hunterloftis

Reputation: 13809

If I understand your question:

var str = '{ "some": "JSON String like the one above with", "rows": 10 }';
var parsed = JSON.parse(str);
var whatYouWant = parsed.rows;

Upvotes: 0

hereandnow78
hereandnow78

Reputation: 14434

you should be json-parsing your whole object and using the parsed object afterwards (you dont need to parse every property for itself)

var strObj = '{"rows": 10,"os": "0","page": "1","total": "122","projects":{"P143841":{"id":"P143841",}}';

var obj = JSON.parse(strObj);
var rows = obj.rows;

Upvotes: 1

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