MVC剃须刀张贴模型为空

Question

Probably missing something obvious here, but my model posted to the controller is always null... The model passes to the view correctly and I can access the properties, but when submitting the form, the model is null. Why?

Model...

public class ProfileModel
{

    public MembershipUser user { get; set; }
    public ProfileSettingsModel settings { get; set; }


}

Controller...

    [HttpPost]
    public ActionResult SaveSettings(ProfileModel model)
    {
        var x = model.user.UserName;
        return View();
    }

View...

 @model MyApp.Models.Profile.ProfileModel

 @using(Html.BeginForm("SaveSettings","Profile"))
    {

        //Tried removing these as I shouldn't need them, but no luck.
        @Html.HiddenFor(x=>x.settings)
        @Html.HiddenFor(x=>x.user)

        @Html.CheckBoxFor(model=>model.settings.VisitorsCanAddMeAsFriend)
        @Html.LabelFor(x=>x.settings.VisitorsCanAddMeAsFriend, "Visitors can add me as a friend")
        @Html.CheckBoxFor(x=>x.settings.VisitorsCanMessageMe)
        @Html.LabelFor(x=>x.settings.VisitorsCanMessageMe, "Visitors can message me")

         <button id="save" type="submit" class="btn btn-default">Save</button>

     }

Rendered HTML...

<form action="/Profile/SaveSettings?HttpMethod=POST&amp;InsertionMode=Replace&amp;LoadingElementDuration=0&amp;AllowCache=False" method="post" novalidate="novalidate">
    <input data-val="true" data-val-required="The VisitorsCanAddMeAsFriend field is required." id="settings_VisitorsCanAddMeAsFriend" name="settings.VisitorsCanAddMeAsFriend" type="checkbox" value="true">
    <input name="settings.VisitorsCanAddMeAsFriend" type="hidden" value="false">
    <label for="settings_VisitorsCanAddMeAsFriend">Visitors can add me as a friend</label>
    <input data-val="true" data-val-required="The VisitorsCanMessageMe field is required." id="settings_VisitorsCanMessageMe" name="settings.VisitorsCanMessageMe" type="checkbox" value="true">
    <input name="settings.VisitorsCanMessageMe" type="hidden" value="false">
    <label for="settings_VisitorsCanMessageMe">Visitors can message me</label>                 
    <button id="save" type="submit" class="btn btn-default">Save</button>
</form>

Is there anything obvious?

Answer 1

Change

@Html.HiddenFor(x=>x.settings)
@Html.HiddenFor(x=>x.user)

To

@Html.HiddenFor(x => x.user.UserName)

The default binder should at least pick that one up.

Answer 2

You cannot use MembershipUser in model binding. Model binding requires that all properties have a public parameterless constructor, and MembershipUser's parameterless constructor is protected. As such, you cannot use it directly. You will need to create your own view model to pass the properties.

So, removing the settings and user HiddenFor's, then biding those properties directly will get you what you want.

Answer 3

I didn't think you could do a html.hiddenfor (complex type), as the value has to represented as a string. In your render html you can see that then two HiddenFor's are not rendered as input type='hidden' ...../

So yes, the obvious error is the two html.hiddenfor. You will need to do a HiddenFor or each property that you wish to receive in the post

Answer 4

In the controller's postback method, the last line says

return View();

but it should say

return View(model);

otherwise you are not passing the model back to the page.