Cannot read property of undefined after JSON parse

Question

I have done an ajax request in my code and it works good. After that I want to extract only the necessary info and re-post it to another script. Until now here is my code:

$.ajax({
        type: "POST",
                url: url,
                data: {xhr_id: xhr_id},
                success: function (jsondata) {

                    var product_data = [];

                      for (var i = 0; i <= 3; i++) {

                        //alert(jsondata.products[i].product_description.toSource());

                        product_data[i] = {};
                        product_data[i]["product" + i] = jsondata.products[i].product_description;

                        //alert(product_data[i]["product" + i].toSource());
                    }
                },
                dataType: "json"
        });

The problem is that both the alerts work fine, displaying the information I want. However, I get an error message of "Uncaught TypeError: Cannot read property 'product_description' of undefined" which breaks the script and prevents me from doing anything else. What am I doing wrong, any ideas?

jsondata.products[i].product_description - you've got a hardcoded loop length your data is obviously less than that length. — tymeJV
– tymeJV, Commented Nov 4, 2016 at 14:33
@Phylogenesis - OP is already doing that. The array is declared and added to inside the success. — tymeJV
– tymeJV, Commented Nov 4, 2016 at 14:36
@tymeJV Oh Jesus, it wasn't the hardcoded loop (I was getting the same error even with dynamic counter), but the '=' operator... What a silly mistake. Thank you for pointing me to that direction. — Arkoudinos
– Arkoudinos, Commented Nov 4, 2016 at 14:40

Ein2012 · Accepted Answer · 2016-11-04 14:38:17Z

2

'product_description' of undefined" what it means is that your are trying to access property on undefined variable. That implies "jsondata.products[i]" resulted in undefined value which have occured due to index out of range.How many records are returned in jsondata 3 or 4,check and adjust the condition in for loop

answered Nov 4, 2016 at 14:38

Ein2012

1,1031 gold badge14 silver badges34 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Vanquished Wombat · Accepted Answer · 2016-11-04 19:34:45Z

The parameter in the success() function of $.ajax is a string. You have to put it through a parse function to make json. See your code below modified but not tested.

$.ajax({
        type: "POST",
                url: url,
                data: {xhr_id: xhr_id},
                success: function (jsondata) {
                    var oData;
                    try { oData=jQuery.parseJSON(jsondata) }
                    catch(err) {
                        alert("Problem parsing json string : " + jsondata)
                        return false
                    }

                    var product_data = [];

                      for (var i = 0; i <= 3; i++) {

                        //alert(oData.products[i].product_description.toSource());

                        product_data[i] = {};
                        product_data[i]["product" + i] = oData.products[i].product_description;

                        //alert(product_data[i]["product" + i].toSource());
                    }
                },
                dataType: "json"
        });

Collectives™ on Stack Overflow

Cannot read property of undefined after JSON parse

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related