Check if Specific Key Exists in Json Array

Question

I an trying to produce a check to determine if a specific key exists in a json array using jQuery. Specifically, if I see this key, I know that that no objects that I want to display on the page were returned from the server.

The simple check that I'm trying to use looks like this:

 if (data.hasOwnProperty('Error - No records found in table')) {
  alert('true');
 }

The array that is returned from the server looks like this:

[{"Error - No records found in table": ""}]

Full Code:

var url = 'https://blahblah.com';
var postData = $('#BranchSpecials').serialize();
var spinnerBig = $('.loadingSpinner');

var getClearanceItems = $.ajax({
 type: 'Post',
 url: url,
 xhrFields: {
  withCredentials: true
 },
 crossDomain: true,
 data: postData,
 dataType: 'json',
 beforeSend: function(xhr) {
  spinnerBig.show();
 }
});

getClearanceItems.done(function(data, jqXHR) {
 var clearance = $("#clearance");
 spinnerBig.hide();
 clearance.empty();

 if (data.hasOwnProperty('Error - No records found in table')) {
  alert('true');
 }

 var items = [];
 $.each(data, function(i, item) {
  items.push('<div class="item-block"><a href="' + url + item.ProdLink + '"><img src="https://blahblah.com/Data/' + item.ProdImage + '" width="104" height="104"/></a><div class="item-meta"><p class="desc"><a href="' + url + item.ProdLink + '">' + item.ProductDesc + '</a></p><p class="itemID">Item #: <a href="' + url + item.ProdLink + '" class="uline">' + item.ProductID + '</a></p></div></div>');
 });

 clearance.append(items.join(''));

 clearance.slick({
  infinite: true,
  slidesToShow: 4,
  slidesToScroll: 4,
  dots: true,
  appendArrows: $('#controls'),
  prevArrow: '<button type="button" class="btn btn-default"><i class="material-icons">chevron_left</i></button>',
  nextArrow: '<button type="button" class="btn btn-default"><i class="material-icons">chevron_right</i></button>'
 });
});

Question: What is wrong with this check?

try if (data[0].hasOwnProperty('Error - No records found in table')) — Pranav C Balan
– Pranav C Balan, Commented May 24, 2016 at 13:21

Pranav C Balan · Accepted Answer · 2016-05-24 13:36:38Z

1

You are checking the property defined for the array not the object, if the array contains single object then get the first object from array and check

if(data[0].hasOwnProperty('Error - No records found in table'))

if multiple elements are there then try the other answer using some() by @AmirPopovich.

edited May 24, 2016 at 13:36

answered May 24, 2016 at 13:34

Pranav C Balan

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1 Comment

Pranav C Balan Over a year ago

@dentalhero : glad to help :)

Amir Popovich · Accepted Answer · 2016-05-24 13:22:03Z

0

The problem is that data is an array and you want to perform the check on the array's items.

Use Array.prototype.some in order to determine is any object in the array contains a key with the error.

var data = [{"Error - No records found in table": ""}];
if (data.some(function(item){ return item.hasOwnProperty('Error - No records found in table') })) {
  alert('true');
 }

answered May 24, 2016 at 13:22

Amir Popovich

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2 Comments

dentalhero Over a year ago

I think Pranav's solution is more efficient in this case since I know that I will only have a single object in the error response. I imagine if I don't know how many objects to expect that your solution would be appropriate. Do you agree?

Amir Popovich Over a year ago

@dentalhero - I think that if you have a single object, there is no need for an array.

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