Message Validation

The first option is declaring validation statement in Entry model class.

For example, we want user not to fill the notes section longer than 200 characters.

[MaxLength(200, ErrorMessage = "Notes cannot be longer than 200")]
public string Notes { get; set; }

The second option is declaring validation statement in Controller class above Add function.

For example, we want user to set the duration with value more than 0.

if(ModelState.IsValidField("Duration") && entry.Duration <= 0 )
{
    ModelState.AddModelError("Duration", "The duration field must be greater than 0");
}

Finaly, to call the error validation message, type the code below on the top of Add view page.

@Html.ValidationSummary("The following errors were found: ", new { @class = "alert alert-danger" })