Disable Required validation attribute under certai

Question

I was wondering if it is possible to disable the Required validation attribute in certain controller actions. I am wondering this because on one of my edit forms I do not require the user to enter values for fields that they have already specified previously. However I then implement logic that when they enter a value it uses some special logic to update the model, such as hashing a value etc.

Any sugestions on how to get around this problem?

EDIT:
And yes client validation is a problem here to, as it will not allow them to submit the form without entering a value.

Answer 1

If you don't want to use another ViewModel you can disable client validations on the view and also remove the validations on the server for those properties you want to ignore. Please check this answer for a deeper explanation https://stackoverflow.com/a/15248790/1128216

Answer 2

This problem can be easily solved by using view models. View models are classes that are specifically tailored to the needs of a given view. So for example in your case you could have the following view models:

public UpdateViewView
{
    [Required]
    public string Id { get; set; }

    ... some other properties
}

public class InsertViewModel
{
    public string Id { get; set; }

    ... some other properties
}

which will be used in their corresponding controller actions:

[HttpPost]
public ActionResult Update(UpdateViewView model)
{
    ...
}

[HttpPost]
public ActionResult Insert(InsertViewModel model)
{
    ...
}

Answer 3

I was having this problem when I creating a Edit View for my Model and I want to update just one field.

My solution for a simplest way is put the two field using :

 <%: Html.HiddenFor(model => model.ID) %>
 <%: Html.HiddenFor(model => model.Name)%>
 <%: Html.HiddenFor(model => model.Content)%>
 <%: Html.TextAreaFor(model => model.Comments)%>

Comments is the field that I only update in Edit View, that not have Required Attribute.

ASP.NET MVC 3 Entity

Answer 4

If you just want to disable validation for a single field in client side then you can override the validation attributes as follows:

@Html.TexBoxFor(model => model.SomeValue, 
                new Dictionary<string, object> { { "data-val", false }})

Answer 5

Personally I would tend to use the approach Darin Dimitrov showed in his solution. This frees you up to be able to use the data annotation approach with validation AND have separate data attributes on each ViewModel corresponding to the task at hand. To minimize the amount of work for copying between model and viewmodel you should look at AutoMapper or ValueInjecter. Both have their individual strong points, so check them both.

Another possible approach for you would be to derive your viewmodel or model from IValidatableObject. This gives you the option to implement a function Validate. In validate you can return either a List of ValidationResult elements or issue a yield return for each problem you detect in validation.

The ValidationResult consists of an error message and a list of strings with the fieldnames. The error messages will be shown at a location near the input field(s).

public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
{
  if( NumberField < 0 )
  {
    yield return new ValidationResult( 
        "Don't input a negative number", 
        new[] { "NumberField" } );
  }

  if( NumberField > 100 )
  {
    yield return new ValidationResult( 
        "Don't input a number > 100", 
        new[] { "NumberField" } );
  }

  yield break;
}

Answer 6

What @Darin said is what I would recommend as well. However I would add to it (and in response to one of the comments) that you can in fact also use this method for primitive types like bit, bool, even structures like Guid by simply making them nullable. Once you do this, the Required attribute functions as expected.

public UpdateViewView
{
    [Required]
    public Guid? Id { get; set; }
    [Required]
    public string Name { get; set; }
    [Required]
    public int? Age { get; set; }
    [Required]
    public bool? IsApproved { get; set; }
    //... some other properties
}