MVC not validate empty string

Question

I have razor file where I define html form with text box for string:

    @using (Html.BeginForm()) {
        @Html.ValidationSummary(true)
        

        

Answer 1

This is what worked for me:
Use the following line to not accept empty string

[Required (AllowEmptyStrings = false)]

and this one to not allow white space

[RegularExpression (@".*\S+.*", ErrorMessage = "No white space allowed")]

Answer 2

what does your viewmodel look like?

You can add a DataAnnotation attribute to your Name property in your viewmodel:

public class MyViewModel
{
    [Required(ErrorMessage="This field can not be empty.")]
    public string Name { get; set; }
}

Then, in your controller you can check whether or not the model being posted is valid.

public ActionResult MyAction(ViewModel model)
{
    if (ModelState.IsValid)
    {
        //ok
    }
    else
    {
        //not ok
    }
}

Answer 3

You probably need to set the DataAnnotation attribute

[Required(AllowEmptyStrings = false)]

on top of your property where you want to apply the validation.
Look at this question here
RequiredAttribute with AllowEmptyString=true in ASP.NET MVC 3 unobtrusive validation

Similar problem, more or less here.
How to convert TextBoxes with null values to empty strings

Hopefully, you'll be able to solve your problem