ASP.NET MVC PartialView postback: how to validate data?

Question

I am using ASP.NET partial views like in this example

<% using (Html.BeginForm()) { %>
    <table cellspacing="2" cellpadding="0" border="0" width="100%">
    <tr>
        <td><%= Html.LabelFor(model => model.PersonName)%></td>
        <td>
            <%= Html.TextBoxFor(model => model.PersonName)%>
            <%= Html.ValidationMessageFor(model => model.PersonName, "*")%>
        </td>
    </tr>
    ...
    <tr><td colspan="2"><%= Html.ValidationSummary(false) %></td></tr>
    </table>
<% } %>

I show these partial views in Jquery dialogs calling them using jquery code

$.ajax({
    type: "get",
    dataType: "html",
    url: urlAction,
    data: {},
    success: function(response) {
        $("#panelDetail").html('').html(response).dialog('open');
    }
});

and everything works and make me happy. I am also able to submit the form using jquery ajax and this make me even more happy. :)

What is really annoying is that I did not understand where validation occurs because, when it happens, it does a full refresh of the page and close the dialog.

I am sure that somebody can help on this. Anyway....who will be? :)

Thanks in advance!

EDIT:

This is the controller action signature with some code in it

[HttpPost]
public ActionResult MyAction(FormCollection form) {
    string foroID = form["ForoId"];
    string foro = form["Foro"];
    string authorityId = form["AuthorityId"];
    string sezione = form["Sezione"];
    ...
}

Do I have to re-create the model class to validate it?

Answer 1

First of all: if you're using client validation, than the first check is already on the client side using JavaScript, but your validation would show errors while typing in data.

Second of all: your data being sent back to controller action is being validated at that particular point as long as your action takes a parameter of the same type as your PartialView has as model type. If this type (class) has data annotations attached to properties, those are being validated. Of course you should as well check for model errors in your action and act accordingly.

A redirect? If you'd provide some more code of your controller action we could more easily check what's going on and provide some additional help.

How did I handle this situation

I created a special action filter that checks for model state errors and returns 400 to the client with error description. All my Ajax calls handle success as well as error replies and act accordingly.

Check the code here (question and solution).

The actual solution

This solution is based on additional information gotten from comments below

So after a discussion the problem isn't actually the full page post-back, but the validation that didn't happen at all. The reason being that controller action takes a parameter of type FormCollection. MVC framework has no knowledge whatsoever to know how to validate that data, so no validation happens.

The change you have to do is to change the type of this parameter, to match your strong type view. If your view is of type ViewPage<MyCustomType> then your HttpPost action should most probably have a parameter of the same type.

In general action type can have parameters of any type. Yes it can have even more parameters. The only restriction being that default model binder will be able to relate posted data to these parameters. This is where you come in. All you have to do is to name your parameters properly and model binder will do the rest.

If you come across a certain situation where this can't be done easily, you can always write a custom model binder for a particular type, and it will be completely on you how to parse posted data.

Answer 2

with Robert's suggestion in here

before you close your dialog box, you try to check what is the server response when you submit the form via ajax before you close the dialog, try to check if the response is valid or invalid model state before you call dialog('close') of the dialog. Same thing in all other situation of dialogs.