Accessing data from code behind in Javascript

Question

I am using devexpress JS Charts which they accept data in a format of:

[{ category: 'Oceania', value: 35 },{ category: 'Europe', value: 728 }]

I am able to get the exact same format in my back end code by converting a DataTable to a Json. (I am getting the datatable after i run a couple of queries based of the user's selection)

Everything was working fine untill i decided to use an UpdatePanel to avoid the postbacks in the page every time the user was selecting an option (Please note that i am not experienced in something like this). Now ,though, i realized that i can't call a non static method with javascript in order to get the data. What i thought i could do is every time i have an ajax postback, i would run a method and insert into a hidden field the data and then grab it with javascript and populate my charts. When i am doing that it's not working as the data is stored as string... I tried a couple of things around it but i simple can't make this work...

I was grabbing the data before (with post back)

var data= <%=GetData()%>

The GetData() is a C# method that returns a string

private string GetJsonFormat(DataTable table)

In order to populate the charts i must use

$("#divID").dxPieChart({dataSource: data});

If i input the data into an input field and grab it like this

var data= $('#inputID').val();

It doesn't work because of the string quotes... I even tried to remove the quotes like this

data.substring(1,data.length()-1)

but didn't work either...

Can someone see an alternative way around this or a fix for this?

If the data is safe, have you tried using eval()?

godfrzero
– godfrzero

2013-08-15 07:33:57 +00:00
Commented Aug 15, 2013 at 7:33 — godfrzero
– godfrzero, Commented Aug 15, 2013 at 7:33

Tom Troughton · Accepted Answer · 2013-08-15 08:58:26Z

1

The correct approach would be to use AJAX. For example, jQuery has built-in functions for getting JSON content from the server.

http://api.jquery.com/jQuery.getJSON/

It's extremely simple. The easiest approach is to get your button (or whatever triggers the event) to simply call:

$.getJSON('url/to/json/content', function(data) {
    // data is the returned JSON object so use it as you like
});

answered Aug 15, 2013 at 8:58

Tom Troughton

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