Develop Reference

Cannot read property of undefined after JSON parse

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?

'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

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"
});

"Synchrounous" AJAX call and web2py

I need some help with "synchronizing" my AJAX calls. I have a function scripted that takes in a file with certain test parameters and uses those parameters to kick off test via an AJAX call/s. The way the code is suppose to work is thatonce the test run is complete, another AJAX call is suppose to update the eventLog with the test results for that run and then move to the next iteration of the for loop.
The ajax calls can be seen in the for loop towards the bottom of the code. I looked into some documentation on using the jQuery Deffered class, but I am pretty new to JavaScript in general and I'm having trouble understanding how that code works. Thanks in advance for any help.
function runTest(modelName, serialNum, passArea) {
//Pull in sequence file
var str = "";
var table = document.getElementById('taskTable');
var output = document.getElementById('outputStrArea');
var passFail = document.getElementById(passArea).innerHTML;
var rowCount = table.rows.length;
for(var i=1; i<rowCount; i++) {
var row = table.rows[i];
str+= row.innerHTML+"\n";
}
str = str.split("<td>");
delete str[0];
delete str[-1];
//Create a list of tests that can be read out
var testList = [];
for (var i=1; i <str.length; i++){
str[i]= str[i].replace("</td>", "");
str[i]= str[i].replace(" ", "");
if (str[i].search("checkbox") < 0){
testList.push(str[i]);
}
}
var model = document.getElementById(modelName).innerHTML;
model = model.replace("<b>", "");
model = model.replace("</b>", "");
model = model.replace(" ", "");
var serial = document.getElementById(serialNum).innerHTML;
var info = model+" "+serial+" ";
for(var k=0; k<testList.length; k+=5){
info+= testList[k]+" "+testList[k+1]+" "+testList[k+2]+" "+testList[k+3]+" "+testList[k+4]+" ";
ajax("loadTestSequence?info="+info, [], passArea);
ajax("loadEventLog", [], 'eventLog');
}
}

The ajax calls have a success callback in which you can invoke another ajax call id you want. Syntax is something like this:
$.ajax({
url: url,
data: data,
success: function(){
$.ajax({
url: url,
data: data,
success: success,
dataType: dataType
});
},
dataType: dataType
});
So now you can chain your respective ajax calls similarly. Hope that helps.

First Time Ajax request getting two url different elements

var memberURL;
var memberAva;
var memberName;
var members = data.find('.userdata');
for (var j = 0; j < members.length; j++) {
membername = $(members[j]).find('.username').text();
memberURL = $(members[j]).find('.username').attr('href');
}
memberAva = $('#advanced-profile-right img:eq[0]');
$.ajax({
url:"/viewonline",
type:"GET",
data: {memberURL, memberName}, //What should i do here?
success: function() {
$.ajax({
url: memberURL,
type:"GET",
data: memberAva
}).done(function() {
$('.user_info_on').append('<div class="on_name"><img src="' + memberAva + '"/></div>');
}
});
});
What I am trying to get from the first ajax request is the members URL and the Members name- then on success make another ajax request to the Members URL (each) and get the Members Avatar. Then on done post the data that is retrieved. Code is not working, and not sure what I should do?
I tried posting on two .get()s though I guess this is the only way? Anyways anyone have suggestions and tips for me?
The .get() that works-
$(function () {
$.get('/viewonline', function (data) {
data = $(data);
var members = data.find('.userdata');
for (var j = 0; j < members.length; j++) {
var membername = $(members[j]).find('.username').text();
var memberURL = $(members[j]).find('.username').attr('href');
});
$('.user_info_on').append('<div class="on_name"><img src=""/></div>'); //In between source of image would be memberAva from the other .get() request.
}
}, 'html');
});

Use a FOR loop within an AJAX call

So, what i'm trying to do is to send an AJAX request, but as you can see i have many fields in my form, and i use an array to make validations, i would like to use the same array, to pass the values to be sent via AJAX:
I never used the for loop in JS, but seems familiar anyway.
The way the loop is made, obviously wont work:
for (i=0;i<required.length;i++) {
var required[i] = $('#'+required[i]).attr('value');
This will create the variables i want, how to use them?
HOPEFULLY, you guys can help me!!! Thank you very much!
required = ['nome','sobrenome','endereco','codigopostal','localidade','telemovel','email','codigopostal2','localidade2','endereco2','nif','entidade','codigopostal3','localidade3','endereco3','nserie','modelo'];
function ajaxrequest() {
for (i = 0; i < required.length; i++) {
var required[i] = $('#' + required[i]).attr('value');
var dataString = 'nome=' + required[0] + '&sobrenome=' + required[1];
}
$.ajax({
type: "POST",
url: "ajaxload/como.php",
data: dataString,
success: function() {
$(".agendarleft").html("SUCESS");
}
});

To help ensure that the appropriate element IDs and values are passed, loop through the various elements and add the data to an object first.
jQuery:
required = ['nome', 'sobrenome', 'endereco', 'codigopostal', 'localidade', 'telemovel', 'email', 'codigopostal2', 'localidade2', 'endereco2', 'nif', 'entidade', 'codigopostal3', 'localidade3', 'endereco3', 'nserie', 'modelo'];
function ajaxrequest() {
var params = {}; // initialize object
//loop through input array
for (var i=0; i < required.length; i++) {
// set the key/property (input element) for your object
var ele = required[i];
// add the property to the object and set the value
params[ele] = $('#' + ele).val();
}
$.ajax({
type: "POST",
url: "ajaxload/como.php",
data: params,
success: function() {
$(".agendarleft").html("SUCESS");
}
});
}
Demo: http://jsfiddle.net/kPR69/

What would be much cleaner would be to put a class on each of the fields you wish to save and use this to iterate through them. Then you wouldn't need to specify the input names either and you could send a json object directly to the Service;
var obj = {};
$('.save').each(function () {
var key = $(this).attr('id');
var val = $(this).val();
if (typeof (val) == "undefined")
val = "''"
obj[key] = val;
}
Then send obj as the data property of your AJAX call....

There are a few issues with your code. 'required' is being overwritten and is also being re-declared inside of the loop.
I would suggest using pre-written library, a few I included below.
http://jquery.malsup.com/form/#validation
https://github.com/posabsolute/jQuery-Validation-Engine
Otherwise the follow would get you close. You may need to covert the array into a string.
var required = ['nome','sobrenome'];
function ajaxrequest() {
var values;
for (i = 0; i < required.length; i++) {
var values[i] = $('#' + required[i]).attr('value');
}
$.ajax({
type: "POST",
url: "ajaxload/como.php",
data: values,
success: function() {
$(".agendarleft").html("SUCESS");
}
});
}

jQuery Ajax call in loop losing local variable reference

I am making several jQuery ajax calls within a loop. Each time one of the ajax calls return I need to reference a value corresponding to the original ajax call. My current code doesn't work properly, in that the value of the lskey variable has been altered by further loop iterations.
Here is the code:
for (var i = 0, len = localStorage.length; i < len; i++) {
var lskey = localStorage.key(i);
if (lskey.substr(0, 4) === 'form') {
var postdata = localStorage.getItem(lskey); // Get the form data
$.ajax({
type: "POST",
async: "false",
url: "/Profile/PostForm",
data: postdata,
success: function (data) {
$('#rollinginfo').append('<br>' + data + ',key=' + lskey);
localStorage.removeItem(lskey); // Remove the relevant localStorage entry
}
, error: function (data) { $('#rollinginfo').append('<br />ERR:' + data); }
});
}
}
The problem is that lskey is being altered each time the loop executes, and therefore the success callback does not have a reference to the value of lskey that existed at the time of the call.
How do I reference the correct value of lskey for each success callback?

for (var i = 0, len = localStorage.length; i < len; i++) {
var lskey = localStorage.key(i);
if (lskey.substr(0, 4) === 'form') {
var postdata = localStorage.getItem(lskey); // Get the form data
$.ajax({
type: "POST",
async: "false",
url: "/Profile/PostForm",
data: postdata,
local_lskey: lskey
success: function (data) {
$('#rollinginfo').append('<br>' + data + ',key=' + lskey);
localStorage.removeItem(this.local_lskey); // Remove the relevant localStorage entry
}
, error: function (data) { $('#rollinginfo').append('<br />ERR:' + data); }
});
}
}
This should work.

In the end I added the key info to the server posting, and then returned it from the server in JSON format so the success function could then simply refer to the key contained in the server response.

Have you considered chaining the AJAX calls? Basically you can make one AJAX call, process the result, modify lskey, etc. Then when you are ready, increment i and issue the second AJAX call. Loop this way instead of using the for loop...

You could put your ajax call into its own function and pass the lskey and postData values in. That way localStorage.removeItem(lskey) will refer to the lskey variable in the context of the function rather than the context of the loop.
Example
Declare the function -
function postForm(postdata, lskey) {
$.ajax({
type: "POST",
async: "false",
url: "/Profile/PostForm",
data: postdata,
success: function(data) {
$('#rollinginfo').append('<br>' + data + ',key=' + lskey);
localStorage.removeItem(lskey); // Remove the relevant localStorage entry
},
error: function(data) {
$('#rollinginfo').append('<br />ERR:' + data);
}
});
}
Then you can call your function from your loop -
for (var i = 0, len = localStorage.length; i < len; i++) {
var lskey = localStorage.key(i);
if (lskey.substr(0, 4) === 'form') {
var postdata = localStorage.getItem(lskey); // Get the form data
postForm(postdata, lskey);
}
}
You could also declare the function just before the loop (assigning it to a variable) and then call it within the loop.
var postForm = function(postdata, lskey) {
$.ajax({
type: "POST",
async: "false",
url: "/Profile/PostForm",
data: postdata,
success: function(data) {
$('#rollinginfo').append('<br>' + data + ',key=' + lskey);
localStorage.removeItem(lskey); // Remove the relevant localStorage entry
},
error: function(data) {
$('#rollinginfo').append('<br />ERR:' + data);
}
});
}
for (var i = 0, len = localStorage.length; i < len; i++) {
var lskey = localStorage.key(i);
if (lskey.substr(0, 4) === 'form') {
var postdata = localStorage.getItem(lskey); // Get the form data
postForm(postdata, lskey);
}
}