A POCO parameter with an exact name match in a value provider fails to model bind

[dougbu]

when POCO model contains a property with the same name as the parameter e.g.

public class Vehicle
{
    public string Model { get; set; }
}
...
[HttpPost("/vehicles/{id:int}/edit")]
public IActionResult Edit(int id, Vehicle model)
{
}

then model will not be initialized -- all properties have default values. rename the Model property or model parameter and everything works as expected.

because the problem relates to model binders falling back to the empty prefix, can workaround it: send field names prefixed with the parameter name e.g.

@model Vehicle
@using (Html.BeginForm())
{
  ViewData.TemplateInfo.HtmlFieldPrefix = "model";
...
  <div class="editor-field">
    @Html.EditorFor(m => m)
  </div>
...
  ViewData.TemplateInfo.HtmlFieldPrefix = string.Empty;
}

bug does not appear to be a regression from MVC 5.2, MVC 6 Beta1, or MVC 6 Beta2.

[dougbu]

original bug is better described in #2129. changing the subject to make it clear the Vehicles model was actually bound incorrectly due to match between property and parameter names. like #2129, the root cause is the model binding system not falling back to an empty prefix. unlike #2129, the problem is specific to top-level POCO models

[dougbu]

realized the "top-level property" in the subject was a bit misleading and have updated the subject again. problems occur when an action parameter's name is an exact match for something in the value providers. so the previously-mentioned property must have a value in the query, form, etc. to cause problems.

also edited the issue description to remove mention of collections.

[dougbu]

commit 533474d