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POwcf deserializing : can we infer javascript type?
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  1. POwcf deserializing : can we infer javascript type?
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    copied!<p>I'm calling an asp.net webservice with JQuery and ajax, transfering data with json. I'm creating javascript objects that will be json stringified. I need my webmethod to retrieve these particular object types but my parameter type is a base class and those objects inherit from my base class like this :</p> <pre><code>[DataContract] [KnownType(typeof(TextareaObject))] [KnownType(typeof(TextObject))] public class FormElement { public FormElement() {} } </code></pre> <p>and : </p> <pre><code> [DataContract(Name = "textObject")] public class TextObject : FormElement { [DataMember] public string question { get; set; } public TextObject(string question) { this.question = question; } } </code></pre> <p>and my webmethod : </p> <pre><code> [WebInvoke(ResponseFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.WrappedRequest)] [OperationContract] [ServiceKnownType(typeof(TextObject))] [ServiceKnownType(typeof(TextareaObject))] public void SaveForm(List&lt;FormElement&gt; formobjects) { ... } </code></pre> <p>And here's the way I'm creating javascript objects (I copy only relevant samples of my code) : </p> <pre><code> //objects to serialize function textObject(question) { this.question = question; } //objects to serialize function textareaObject(question, rownumber) { this.question = question; this.rownumber = rownumber; } var objectarray = new Array(); if (type == 'text') { textobject1 = new textObject(typedquestion); objectarray.push(textobject1); } else if (type == 'textarea') { var rownumber = $(elm).children('textarea').attr('rows'); textareaobject1 = new textareaObject(typedquestion, rownumber); objectarray.push(textareaobject1); } var formobjects = JSON.stringify(objectarray); $.ajax({ type: "POST", //Page Name (in which the method should be called) and method name url: urlhtml, data: '{"formobjects":' + formobjects + '}', contentType: "application/json; charset=utf-8", dataType: "json", success: function (msg) { //dosmth } }); </code></pre> <p>And I want asp.net server to be able to deserialize the correct type in my array. But once in my webmethod, "formobjects" are all of type FormElement, I can't get their real type even with serviceknowntype attributes. Is is because javascript isn't strongly typed that I can't retrieve the concrete types ? because the stringified json won't give the concrete type? I tried with </p> <pre><code> textObject.prototype = new textObject(typedquestion); objectarray.push(textObject.prototype); </code></pre> <p>and the json gives something like :</p> <pre><code>{"formobjects":{"textObject": {"question":"test"}}} </code></pre> <p>But server side same old same old, I only get FormElement type in my webmethod and I can't cast.</p> <p>maybe what I wanna do is not possible.. thank you anyway !!</p>
 

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