prepopulate Html.TextBoxFor in asp.net mvc 3

Question

I'n new at this, so apologies if this isn't explanatory enough. I want to prepopulate a field in a form in asp.net mvc 3. This works;

@Html.TextBox("CompName", null, new { @value = ViewBag.CompName })

But when I want to prepopulate it with a value and send that value to my model, like this;

 @Html.TextBoxFor(model => model.Comps.CompName, null, new { @value = ViewBag.CompName })

It won't work. Any ideas?

Thanks in advance!

Answer 1

So, I would suggest is to move to using viewmodels rather than the ViewBag. I made a folder in my project called ViewModels and then under there make some subfolders as appropriate where I put my various viewmodels.

If you create a viewmodel class like so:

public class MyViewModel
{
   public string CompName { get; set; }
}

then in your controller action you can create one of those and populate it, maybe from some existing model pulled from a database. By setting that CompName property in the viewmodel, it'll have that value in your view. And then your view can look something like this:

@model MyNamespace.ViewModels.MyViewModel

@Html.EditorFor(model => model.CompName)

or @Html.TextBoxFor would work too.

Then back in your controller action on the post, you've got something like this:

[HttpPost]
public ActionResult MyAction(MyViewModel viewModel)
{
   ...
   // do whatever you want with viewModel.CompName here, like persist it back
   // to the DB
   ...
}

Might be that you use something like automapper to map your models and viewmodels but you could certainly do that manually as well, though the whole lefthand/righthand thing gets quite tedious.

Makes things much easier if you do it this way and isn't much work at all.

---

Update

But, if you really want to pass that value in view the ViewBag, you could do this:

In your controller action:

ViewBag.CompName = "Some Name";

Then in your view:

@Html.TextBoxFor(model =>model.Comps.CompName, new {@Value = ViewBag.CompName})

And that'll pre-populate the textbox with "Some Name".

I'd still go with the viewmodel approach, but this seems to work well enough. Hope that helps!

Answer 2

From your controller, if you pass a model initialized with default values using one of the View(...) method overloads that accepts a model object, these values will be used by the view when rendered. You won't need to use the @value = ... syntax.