In my ViewModels I use several DataAnnotations to validate the form data, there are usually 2-3 annotations per field.
For example a field for an email address might look like this:
[Required(ErrorMessage = "Please enter an email address.")]
[Email(ErrorMessage = "That is not a valid email address.")] // Custom
public string Email { get; set; }
Now if someone were to submit the form, both errors would show up in the validation summary. Is there any easy way to specify an order to run the validation annotations so that if the Required validation fails, the Email validation doesn't run?
If this isn't possible, how is this usually handled? Should I create custom validators for any field that has more than a single annotation? Would that be a proper way to use annotations, where a single one handles multiple types of validation?
(I'm also aware I could probably combine the Required annotation into the custom Email one, but this is just an example).
In this specific case I would probably take the same approach that the ASP.NET WebForms validators take - simply have the EmailAttribute validator return true if the value is null or empty.
Think about it:
If the e-mail address is required, then there will also be a [Required] validator and a null/empty e-mail address will generate a validation error anyway;
If the e-mail address is optional, a null/empty value should be considered valid.
No need to solve the complex problem of intercepting validators when you can just design the individual validators to play nice together!
Ordering validation: No.
In this case you could simply remove the Required attribute because "" or " " will fail the email address validation.
And yes, AFAIK creating a custom validation attribute that combines both of them is probably your best bet.
The problem here is that the ordering on the attributes is completely arbitrary and decided at compile time. You actually can enforce simple ordering depending on the kind of validation runner you're using. If you are using something like xVal and a validation runner like the one mentioned here, you can add an orderby clause like this to force a specific kind of attribute to sort to the top:
orderby attribute.GetType() == typeof(T) ? 0 : 1
Just make a strongly-typed validation runner method, where T is derived from the ValidationAttribute class.
Related
After a year or so of MVC experience I'm still confused about one thing: How to effectively use the DataAnnotations with ModelState.IsValid? For simple tutorial example this all works just fine and I have no questions about that. But supposed I have the following model:
Public Class Movie
Public Property MovieID As Integer
Public Property Title As String
Public Property Year As Integer
Public Property AddedByUser As String
End Class
Now the field AddedByUser is required in the database however I don't want the user to provide this but rather the business logic based on the currently logged in user. How would I use the DataAnnotation attributes for this scenario? If I make this field required then in the controller when I say:
Public Function SaveMovie(ByVal entity as Movie) As ActionResult
If ModelState.IsValid
// Save to DB here...
End If
Return View(entity)
End Function
... the validation will fail because I don't have that field in the view bindings. Should I have a hidden field for this? Should I write a custom view model for SaveMovie action? I suppose I could write my own validation in business logic but then why use model validation at all? Custom model binder perhaps? What is the best way to handle these types of scenarios?
Just to give another example scenario what about the difference between insert and update operation and validation? For update operations object's primary key is required. However that is not the case for inserts. Are you supposed to have separate models for insert and update just because of this one key property?
so the way that I handle this is I use the DataAnnotation based validation for user input type stuff. i.e. Validation on email addresses, dates, required fields etc. Stuff that you need a quick 'sanity check' on and need to double check the users entries on.
I don't put any DataAnnotations on the fields that my Database controls or my code controls, i.e. Primary Keys, your [AddedByUser] property as the user doesn't access these properties directly and so you shouldn't have to add validation checks on this. Since your code is the only thing that updates these properties, why validate them?
For more 'business rule' type validation I implement IValidatableObject on my model which gets run, in MVC, after all property-level validations have succeeded. Note that it won't run if the property-level validations fail. And this makes sense, because if the data is 'dirty' you wouldn't want to proceed to run more complex validation etc.
Hope this helps :)
I am using MVC3 and in certain locations in the code I am using the System.ComponentModel.DataAnnotations.DataType.EmailAddress attribute and letting MVCs Model validation do the validation for me.
However, I would now like to validate an email address in a different section of code where I am not using a model. I would like to use the same method that is already being used by MVC, however I was unable to find any information on how to do so.
EDIT - Sorry if my question was unclear. I will attempt to clarify.
Here is a snippet from the RegisterModel that is included with the default MVC template:
public class RegisterModel
{
...
[Required]
[DataType(DataType.EmailAddress)]
[DisplayName("Email address")]
public string Email { get; set; }
...
}
These attributes instruct mvcs model validation on how to validate this model.
However, I have a string that should contain an email address. I would like to validate the email address the same way that mvc is doing it.
string email = "noone#nowhere.com";
bool isValid = SomeMethodForValidatingTheEmailAddressTheSameWayMVCDoes(email);
As others have said, the DataType attribute doesn't actually do any validation. I would recommend you to look at Data Annotations Extensions which includes already written validation extensions for a variety of things, including Email.
It is also possible to do model validation on your full model explicitly: Manual Validation with Data Annotations.
If you want to do per attribute validation for a specific field/property, you can also look at the tests for DataAnnotationExtensions which should give you what you want:
[TestMethod]
public void IsValidTests()
{
var attribute = new EmailAttribute();
Assert.IsTrue(attribute.IsValid(null)); // Don't check for required
Assert.IsTrue(attribute.IsValid("foo#bar.com"));
..
}
Have a look at this blog post by Scott Guthrie, which shows how to implement validation of an email address using a custom attribute (based on the RegularExpressionAttribute).
You can reuse that logic if you need to validate the email address somewhere else.
You may want to look at this question: Is the DataTypeAttribute validation working in MVC2?
To summarize, [DataType(DataType.EmailAddress)] doesn't actually validate anything, it just says "hey, this property is supposed to be an e-mail address". Methods like Html.DisplayFor() will check for this and render it as foo, but the IsValid() method is pretty much a simple return true;.
You'll have to roll your own code to actually perform validation. The question linked above has some sample code you can use as a starting point.
I am developing a site that uses the built in account model / controller that comes with the new MVC site template. I want to be able to only allow people to register if they use one of two specific domains in their email address.
So for example they can register if they use #domain1.co.uk or #domain2.co.uk, but no other domains (for example Gmail, Yahoo etc) can be used.
If anyone could point me in the right direction that would be great.
If using the MVC3 default site, you'll have a /Models/AccountModels.cs file. You can add a regular expression there to cause client-side* and server-side validation.
public class RegisterModel
{
...
[Required]
[DataType(DataType.EmailAddress)]
[Display(Name = "Email address")]
[RegularExpression(#"^[a-zA-Z0-9._%+-]+(#domain1\.co\.uk|#domain2\.co\.uk)$", ErrorMessage = "Registration limited to domain1 and domain2.")]
public string Email { get; set; }
...
}
You will need to work out the expression that works out best for your requirements.
*client-side validation assumes your view references the jquery.validate script and has Html.ValidationMessageFor(m => m.Email) and/or Html.ValidationSummary(), which it should by default.
What more do you need than:
if( email.Contains("#domain1.co.uk") || email.Contains("#domain2.co.uk") )
Register(email);
else
throw, return false, whatever()
When it comes time to do your validation, i.e. is the email field populated, use a regex to make sure it is in the domain. As for what the actual regex should be, there is a lot of discussion online about validating email addresses with them. It even comes down to what a valid email address should contain. I found this example online, but it likely by no means the best solution, as I am not a regex expert. I have tried it with a few examples but I'm sure you can come up with some that will pass when they shouldn't:
^\w+([-+.']\w+)*#mail.com$
Where mail.com is the domain you want to check against. If you have multiple domains, you can either extend the regex or do multiple checks replacing mail.com in the regex with whatever else you want to use.
BTW I found that regex on this forums.asp.net post which touches on an issue like yours.
Validate that on both the frontend (the reg form) and the backend.
Here I recommend jquery validation plugin for client side validation.
We're using xVal and the standard DataAnnotationsValidationRunner described here to collect validation errors from our domain objects and view models in ASP.NET MVC. I'd like to have a way to have that validation runner identify when two properties don't match through the use of custom DataAnnotations.
Right now I'm forced into doing it outside of the runner, this way:
if (!(model.FieldOne == model.FieldTwo))
errors.Add(new ErrorInfo("FieldTwo", "FieldOne must match FieldTwo", model.FieldTwo));
My question is: can this be done using property-level validation attributes, or am I forced into using class-level attributes (in which case, I'd have to modify the runner...and my follow up question would be how best to retrieve them in that case).
Thanks!
UPDATE: I finally figured out how to write the object query to implement the suggestion in the selected answer; I concat the results of this query with the results of the standard validation runner, if anyone was curious. Note that I changed the TypeId to be the confirm field property.
var classErrorQuery =
from attribute in
instance.GetType().GetCustomAttributes(typeof (ValidationAttribute), false).Cast
<ValidationAttribute>()
where !attribute.IsValid(instance)
select new ErrorInfo(attribute.TypeId.ToString(), attribute.FormatErrorMessage(string.Empty), instance);
see Writing a CompareTo DataAnnotation Attribute
and also you can check The AccountMOdel in the default project of MVC2, There is an attribute PropertiesMustMatchAttribute applied to the ChangePasswordModel to validate that the NewPassword and ConfirmPassword Match
I've read a number of articles now in regard to validation and asp.net mvc and the majority tend to point to validation in the model. The problem I see with all of them is that they don't handle different scenarios, or at least, they don't show how they would be achieved e.g.
When creating or updating a user account the email address must match the email confirmation input. This email confirmation input isn't part of the model it's purely to assist correct user input, this might be called a virtual property. When a user logs in using their email address the validation shouldn't try and match the email against a confirmation input, however, in all the examples I've seen there is no way to differentiate between scenarios where the same data is validated in a different way.
Can anybody point me to any mvc validation articles that handle the above types of problem? Or does anybody have any advice on best practices to handle validation like this?
I had thought about introducing a "validation action" such as create, read, update, delete, and then I could validate the same bit of data depending on the context in which it is being used. Anybody have any thoughts on doing things in this manner?
Thanks in advance for any help
This is why I'm using Validators separated from Models. So, I have IValidator and different validators. For instantiate validator I use DI Container (StructureMap for example).
It was described (not by me) here:
Issues with my MVC repository pattern and StructureMap
According to my experience
1. Validator should be decoupled from controller into separate Service layer like, for instance, showed in this tutorial:
http://www.asp.net/learn/mvc/tutorial-38-cs.aspx
2. Service methods may encapsulate all the kind of validation. For example:
public bool PlaceBooking(Booking booking)
{
//Model validation
IEnumerable<ErrorInfo> errors = DataAnnotationsValidationRunner.GetErrors(booking);
if (errors.Any())
_validationDictionary.AddErrors("error", errors);
// Business rule: Can't place bookings on Sundays
if(booking.ArrivalDate.DayOfWeek == DayOfWeek.Sunday)
_validationDictionary.AddError("ArrivalDate", "Bookings are not permitted on Sundays");
if (!_validationDictionary.IsValid) return false;
//Errors comming from Data Access Layer
try
{
return _dao.Save(booking);
}
catch (DBExecutionException ex)
{
if (ex.ResultCode == ResultCodes.RES_UNIQUEINDEX)
_validationDictionary.AddError("error", "Booking already exists.");
else
_validationDictionary.AddError("error", "Some other DB issue happens.");
}
return false;
}