SyntaxError: JSON.parse: unexpected character for null results

Question

I know that the same topic is asked by several people, but I cannot find an answer for my problem from these questions. I have the following code,

$.post("show_search_results.php", {location_name: ""+location_name+"", key: ""+key+"", category_id: ""+category_id+"", page_number: ""+page_number+""}, function(data){
if(data.length >0){
    var dataArray = JSON.parse(data);
    var result_count=(dataArray.root.data.partners).length;
    if(result_count > 0){
        //block a;
    }else if(s_limit==0){
        //block b;
    }else{
        //block c;
    }
}});

I am using php as back end. this code works fine in my local server and works fine in live server with the following json.

{"root": {"success":"1","message":"Successfully retrieved data.","data":{"partners":[{"store_name":"Mega Mart (Readymade Brands)","store_address":"Next to SBI, Vyttila, Ernakulam","store_phone":"","item_name":"Festival of Young at 999","item_description":"Megamart celebrates the spirit of being young. Take home 4 groovy T-shirts or 2 stylish shirts  or 3 women kurtas for just rupees 999.","item_offer":"999 Offer","offer_expiry":"2014-06-08","tag1":"T-shirt","tag2":"Dress","tag3":"Jeans","store_id":"a9e12c46-ee00-11e3-a5e4-bc305be6e93e"}]}}}

But for this json,

{"root": {"success":"2","message":"no results found","data":{"partners":[]}}}

in live server it shows,

SyntaxError: JSON.parse: unexpected character
var dataArray = JSON.parse(data);

I have tried to remove JSON.parse from my code but it shows

TypeError: dataArray.root is undefined
var array_locations=dataArray.root.data.locations;

Please help me to find a solution. Thanks.

Answer 1

So you shouldn't really need to be doing JSON.parse by hand - jQuery can do this for you if you tell it to expect JSON. It usually uses the Content-Type header in the return response but you can tell it to parse JSON:

$.post({
    url: "show_search_results.php", 
    data: {
        location_name: ""+location_name+"", 
        key: ""+key+"", 
        category_id: ""+category_id+"", 
        page_number: ""+page_number+""
    }, 
    dataType: "json",
    success: function(data){
        // do something with data here...
        alert(data.root.message);
    }
});

By the way - I tried putting the JSON you specify there into the JSON.parse on the Chrome debug console and it worked fine. There's nothing wrong with that JSON.

Answer 2

Change your condition like this.

if(data.length >0){
    var dataArray = JSON.parse(data);

    if(typeof dataArray.root != undefined && dataArray.root.success == 1) {
        // Success
    }
    else {
       // Failure
    }
}