View not updating after post

问题:

I have a controller method CreateOrUpdate, this method is supposed to save the car to the database and then return as normal.

public ActionResult CreateOrUpdate(int ID = 0)
{
    Car car = new Car(ID);
} 

[HttpPost]
public ActionResult CreateOrUpdate(Car car)
{
       car.Save();
       return View(car);
}

In the theCar.Save() method, i set the id for the car, with whatever the id will be in the database after the car is saved (When doing an insert I use SCOPE_IDENTITY(), the save method works well, and if i debug and watch the values for car after the Save() is called, the id is correct. But when the View is rendered the ID is 0 in the view.

Could anyone please help me,and tell me why this would happen. Am I not suppose to change the Model for the view in the HTTP POST method ? Should i Rather redirect to the original CreateOrUpdate() method if the save was successful.

回答1:

it should be the ModelState problem. if you use Htmlhelper to Display id value. Default HtmlHelper display ModelState value not Model. Try display model value in view

<td>
    @Model.id
</td>

or Clean ModelState Value in controller

ModelState.Clear();

or reset id value after SaveChange.

theCar.Save();
ModelState["id"].Value = theCar.id
return View(theCar);

Reset the value of textarea after form submission

回答2:

I added ModelState.Clear() to my HttpPost Controller method, as seen in this post Html helpers get data from model state and not from model if you return the same view after form post. to get updated data in the view use post redirect get pattern or ModelState.Clear() and it solved the problem.

Thanks

回答3:

I didn't want to clear the ModelState because I needed to display errors, so I went with

ValueProviderResult vpr = new ValueProviderResult("", null, System.Globalization.CultureInfo.CurrentCulture);

ModelState["id"].Value = vpr;