c# - Passing JSON serialized data via hidden field - Stack Overflow

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In ASP.NET WebForms I want to pass arbitrary data from server to client and back again. I am serializing to JSON and have been simply producing JavaScript that creates the object on the client. I have no problem sending data to the server with ajax, but there are situations where I also want to send a Javascript object data back to the server on postbacks. So I guess it needs to be in a hidden field.

A couple general questions about this.

1) What is the best way to do this in terms of minimizing plexity and optimizing space and efficiency? In researching this I discovered Protocol Buffers but there does not seem to be a good C# implementation. I did find one, but it was a couple years old and self-described as buggy so that scared me.

2) If I just pass a JSON string, how can I be sure it will be safe to include as the value for a hidden field? Is there any reason I might not want to do this? I could Base64 encode, but it seems like this adds a lot of overhead. What is considered the best or preferred method?

In ASP.NET WebForms I want to pass arbitrary data from server to client and back again. I am serializing to JSON and have been simply producing JavaScript that creates the object on the client. I have no problem sending data to the server with ajax, but there are situations where I also want to send a Javascript object data back to the server on postbacks. So I guess it needs to be in a hidden field.

A couple general questions about this.

1) What is the best way to do this in terms of minimizing plexity and optimizing space and efficiency? In researching this I discovered Protocol Buffers but there does not seem to be a good C# implementation. I did find one, but it was a couple years old and self-described as buggy so that scared me.

2) If I just pass a JSON string, how can I be sure it will be safe to include as the value for a hidden field? Is there any reason I might not want to do this? I could Base64 encode, but it seems like this adds a lot of overhead. What is considered the best or preferred method?

• c#
• javascript
• asp
• serialization
• webforms

Share Improve this question Follow edited Mar 2, 2011 at 20:58 Jamie Treworgy asked Mar 2, 2011 at 20:52 Jamie TreworgyJamie Treworgy 24.4k99 gold badges8080 silver badges119119 bronze badges 6

• Why aren't you using session variables? (just curious) – Brad Christie Commented Mar 2, 2011 at 20:58
• How would I get that data from the client (in javascript)? – Jamie Treworgy Commented Mar 2, 2011 at 20:59
• @Jamietre: Handlers and AJAX, the same way you're posting it back? (ashx/asmx) – Brad Christie Commented Mar 2, 2011 at 20:59
• Ajax is fine, and I could fire off an ajax call before a page got posted, I suppose, but if it's being posted anyway that seems an unnecessary trip to the server. And it's something else I would have to intercept. – Jamie Treworgy Commented Mar 2, 2011 at 21:01
• @jamietre: I guess I need more insight in to the "original problem" before making a judgement call. I can remend methods all day that contour to what you already have deemed suitable, but that doesn't help you solve the original problem at-hand. – Brad Christie Commented Mar 2, 2011 at 21:03

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1 Answer 1

Sorted by: Reset to default 6

In the past, I've usually done the following:

1. Created a C# object that I can easily serialize to XML (.Net can do this natively and there are JSON serializers out there as well). (Actually I think .Net may do JSON as well... not sure though)
2. Take this object and share it with the client via a hidden field or lazy load it on the client via an AJAX request.
3. The client then parses and manipulates the XML (jQuery can do this) and sends it back to the server via AJAX or a hidden field via a POST.
4. Lastly I deserialize the XML (or JSON) from the client back into an Object and work with it from there.

So I'm not sure what you're trying to gain through encoding, but I think the expense of transforming the object from JSON (or XML) to something smaller is too much overhead for any packaging/shrinking benefit. (Unless your a super high traffic site concerned more about bandwidth usage than server/client side processing.)

EXAMPLE

Hopefully this gives you an idea of how to acplish this. Let me know if you have any more questions.

<html> 
<head> 
</head> 
<body> 
    <input type="button" id="btnObject" value="Show Object" /> 
    <input type="button" id="btnShowHid" value="Show Hidden Input Value" /> 
    <input type="hidden" id="hidInput" value="" /> 
</body> 
</html> 
<script type='text/javascript' src='https://ajax.googleapis./ajax/libs/jquery/1.5.0/jquery.min.js'></script>
<script type='text/javascript' src='https://github./douglascrockford/JSON-js/raw/master/json2.js'></script> 
<script> 
    //Your JSON Object
    var myJSONObject = {"bindings": [ 
            {"ircEvent": "PRIVMSG", "method": "newURI", "regex": "^http://.*"}, 
            {"ircEvent": "PRIVMSG", "method": "deleteURI", "regex": "^delete.*"}, 
            {"ircEvent": "PRIVMSG", "method": "randomURI", "regex": "^random.*"} 
        ] 
    }; 

    //jQuery Document Ready Event
    $(function(){
         //Get a reference to your hidden field
        var $hidInput = $("#hidInput");

        //Use json2.js library to convert the json object to a string
        //and assign it to the hidden input's value
        //NOTE: ASP.NET hidden input control reduces to a hidden input so you can treat them the same.
        $hidInput.val(JSON.stringify(myJSONObject));

        //Set up click events to view object and hidden value
        $("#btnShowHid").click(function(){
            alert($hidInput.val());
        });

        $("#btnObject").click(function(){
            alert(myJSONObject);
        });

    });
</script> 

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