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javascriptarraysjson
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Reputation: 1361

Delete JSON items based on array of allowed items

I have an array of allowedFields based on the names of the keys from a JSON array generated from a form.

A number of the retrieved fields are not required at this stage and therefore should not go through the validation process, therefore I want to match the values of the JSON array with the values of the allowedFields array

Returned JSON from form

{"reference":"sdfsdfsdfsd",
"start_date":"04/22/2014",
"end_date":"05//2014",
"status":"1","frequency":"M",
"day":"sat",
"contract_type":"S",
"notice_period":"1M"}

allowedFields = array(
     reference,
     start_date,
     end_date,
     contract_type
)

Basically I need to strip out any fields that are not listed in the allowedFields javascript array

Upvotes: 0

Views: 44

Answers (3)

Mosho
Mosho

Reputation: 7078

underscore.js solution:

_.pick(obj,allowedFields)

http://underscorejs.org/#pick

demo

There is also _.omit(obj,string|string[]) that does the opposite.

underscore.js is extremely useful and I use it quite a bit, but you can also pick just the tools you need and include those in your code. The library is quite optimized and there is no need to write your own.

Here is the implementation (from here)

_.pick = function(obj, iterator, context) {
    var result = {};
    if (_.isFunction(iterator)) {
      for (var key in obj) {
        var value = obj[key];
        if (iterator.call(context, value, key, obj)) result[key] = value;
      }
    } else {
      var keys = concat.apply([], slice.call(arguments, 1));
      for (var i = 0, length = keys.length; i < length; i++) {
        var key = keys[i];
        if (key in obj) result[key] = obj[key];
      }
    }
    return result;
  };

Upvotes: 0

Andy
Andy

Reputation: 63589

1) Parse the JSON to an object.

var obj = JSON.parse(json);

2) Ensure that you've defined your array correctly.

var allowedFields = ['reference','start_date','end_date','contract_type'];

3) Loop over the object and if the key is not in the array delete it.

for (var k in obj) {
  if (allowedFields.indexOf(k) < 0) delete obj[k];
}

4) Stringify your object back to JSON.

var str = JSON.stringify(obj);

Output

{"reference":"sdfsdfsdfsd","start_date":"04/22/2014","end_date":"05//2014","contract_type":"S"}

Fiddle

Upvotes: 1

Phil H
Phil H

Reputation: 20151

var all = {"reference":"sdfsdfsdfsd",
           "status":"1"};
var allowedFields = ['reference']; // note quote marks to create strings

function filter(data, allowed) {
   var filtered = {};
   for(var id=0; id < allowed.length; ++id) {
      var allowedField = allowed[id];
      if(data.hasOwnProperty(allowedField)) {
         filtered[allowedField] = data[allowedField];
      }
   }
   return filtered;
}

console.log(filter(all, allowedFields));
>> [object Object] {
>>  reference: "sdfsdfsdfsd"
>> }

Demo

Upvotes: 1

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