将字典数据从视图传递到控制器

Question

A while ago, I was trying to pass a dictionary data from my view to my controller. And I was able to do so after googling on the net(remember it was one of Scott Hanselman's posts). The solution I had was something like

<%for(int index=0; index<Model.Count(); index++){
     var property= Model.ElementAt(index);%>
     <input type="hidden" name="<%="properties["+index+"].Key"%>"/>
     <input type="hidden" name="<%="properties["+index+"].Value"%>"/>
<%}%>

public ActionResult Process(IDictionary<string,string> properties)
{
      doSomething();
      return View();
}

The code worked for awhile and then I did some refactoring and got rid of this chunk of code. Today, I ran into a situation in which I would like to pass a dictionary again. But no matter how hard I try, the properties parameter received by the action was always null. I tried the above code and

<%for(int index=0; index<Model.Count(); index++){
     var property= Model.ElementAt(index);%>
     <input type="hidden" name="<%="properties.Keys["+index+"]"%>"/>
     <input type="hidden" name="<%="properties.Values["+index+"]"%>"/>
<%}%>

Neither code worked. I googled again but couldn't find the post that helped me before. Can someone point out what I did wrong? thanks a million.

Update : It turned out that the problem is because the generated html code does not have continuous incrementing indexes. For instance, I was getting properties[0], properties[1], properties[3]...(properties[2] was missing). So, firebug would be your best friend when encountering this kind of problems.

Answer 1

You have your indexer in the wrong place, it has to be an index on the properties object.

<%for(int index=0; index<Model.Count(); index++{
     var property= Model.ElementAt(index);%>
     <input type="hidden" name="<%="properties["+index+"].Key"%>"/>
     <input type="hidden" name="<%="properties["+index+"].Value"%>"/>
<%}%>

Answer 2

When i have this kind of problem i allways check the FormCollection Keys, to ensure that it contains the spectated keys, you can do this by putting a breakpoint at the ActionMethod.

public ActionResult Process(IDictionary<string,string> properties, FormCollection f)

And check if "f" has the correct keys.

You can also try

TryUpdateModel(properties, "properties");