Is there away to add and remove DataAnnotations, in particular the [requried], from the code side of things? My problem is that I want to give the user the ability to save an incomplete form in our CRUD applications but at the same time use the power of the DataAnnotations validation.
If this is not possible, what is the best way I can go about this?
You can keep the DataAnnotation attributes on your model and then just manually clear the validation errors as needed from code. It might look something like this:
if (certainCondition == true) {
ModelState["someKey"].Errors.Clear();
ModelState["anotherKey"].Errors.Clear();
}
It is impossible to add, remove or modify DataAnnotations dynamically since they are Attributes. Attributes are part of the type and can't be changed during runtime.
You could use ModelState as Larsenal suggested provided that:
you use it After validation has executed. (prior to that, ModelState will be empty. It doesn't provide access to all validators, it only stores validator-errors after they've occurred)
you don't have any clientside validation that's based on the DataAnnotationValidators and fires errors that prevent you from even reaching the serverside validation.
Related
I have to validate three things when a consumer of my API tries to do an update on a customer.
Prevent the customer to be updated if:
The first name or last name are blank
For a certain country, if the customer's inner collection of X is empty, then throw an exception. X is hard to explain, so just assume it's some collection. For all other countries, X doesn't apply / will always be empty. But if it's a certain country, then X is required. So it's almost a conditional required attribute. A customer belongs to a country, so it's figured out from the JSON being sent.
Prevent the customer from being updated if some conditions in the database are true.
So basically i'm stuck with the following problem, and I wanted some advice on the most appropriately way to solve it:
Do I create an Action Filter to do the validation on the customer entity before the saving takes place? Or would it be better to create custom validation attribute derived from ValidationAttribute and override the IsValid member function.
Basically a question of saying
if (first name is empty, if x, if y, etc) vs (!ModelState.IsValid)
And then using IsValid to cause the custom attributes to work.
It seems like validation attributes are best for "simple" validation, i.e. required field. But once you start getting into things like "I need to look at my database, or analyze the http request header for custom values, and based on that, invalid = false" then it almost seems wrong to do this sort of stuff so close to the entity.
Thoughts?
Thanks!
I like FluentValidation a lot: https://github.com/JeremySkinner/FluentValidation
As you mentioned built-in validation attributes are limited. For complex validations you had better implement your own attributes or use a library like this.
One thing I like about FluentValidation is that it performs at model-level rather than field-level, meaning that you can use related fields' values for validation. For example
RuleFor(customer => customer.Discount).NotEqual(0).When(customer => customer.HasDiscount);
(Code excerpt taken from project's Wiki page)
It's also extensible so you can develop your own custom validators on top of this library as well.
I'm attempting to use client-side validation in an admin page in Orchard. I've been successful at making it work using the techniques discussed in this question, but after doing some digging in the Orchard source and online, it seems to me that commenting out these lines
// Register localized data annotations
ModelValidatorProviders.Providers.Clear();
ModelValidatorProviders.Providers.Add(new LocalizedModelValidatorProvider());
is subverting some built-in Orchard functionality which allows for localized error strings. At this point, either having these lines in our out of OrchardStarter.cs is the only difference between validation working and not working for me.
What I'm hoping for is some guidance on this, maybe from the Orchard team. If these lines have to be out in order for validation to work, why are they there in the first place? If they are there for a good reason, what am I (and others) doing wrong in our attempts to get client-side validation working? I'm happy to post code samples if needs be, although it's a pretty standard ViewModel with data annotations. Thanks.
The lines are there to replace the DataAnnotationsModelValidatorProvider (DAMVP) with Orchard's own implementation, which allows localizing the validation messages the Orchard way. The way it does this is by replacing e.g. [Required] with [LocalizedRequired] before passing control on to the DAMVP. Note that DAMVP does get to do its job - but only after Orchard has "messed" with the attributes.
The problem is that DAMVP uses the type of the Attribute to apply client validation attributes. And now it won't find e.g. RequiredAttribute, because it's been replaced by LocalizedRequiredAttribute. So it won't know what - if any - client validation attributes it should add.
So, out-commenting the lines will make you lose Orchard's localization. Leaving them in will make you lose client validation.
One workaround that might work (haven't looked enough through Orchard's code, and haven't the means to test at the moment) would be to make DAMVP aware of Orchard's Localized attributes and what to do with them.
DAMVP has a static RegisterAdapter() method for the purpose of adding new client rules for attributes. It takes the type of the attribute and the type of the Client-side adapter (the class that takes care of adding client attributes) to use.
So, something like the following might work:
In OrchardStarter.cs:
// Leave the LocalizedModelValidatorProvider lines uncommented/intact
// These are the four attributes Orchard replaces. Register the standard
// client adapters for them:
DataAnnotationsModelValidatorProvider.RegisterAdapter(
typeof(LocalizedRegularExpressionAttribute),
typeof(RegularExpressionAttributeAdapter)
);
DataAnnotationsModelValidatorProvider.RegisterAdapter(
typeof(LocalizedRequiredAttribute),
typeof(RequiredAttributeAdapter)
);
DataAnnotationsModelValidatorProvider.RegisterAdapter(
typeof(LocalizedRangeAttribute),
typeof(RangeAttributeAdapter)
);
DataAnnotationsModelValidatorProvider.RegisterAdapter(
typeof(LocalizedStringLengthAttribute),
typeof(StringLengthAttributeAdapter)
);
As for the official word, it would seem this hasn't worked since localized validation was introduced in 1.3, and the impact is considered low: http://orchard.codeplex.com/workitem/18269
So, at the moment, it appears the official answer to the question title is, "it shouldn't".
I am having problems trying to invoke just one validator on it own, I know how to call on all validators to perform checks on buttons click events, by using Page.Validate() but how can I invoke lets say mySingledOutValidator I tried mySingledOutValidator.Validate() but that's not gonna work individual controls don't have .validate()
I need the following to be true:
Get a single validation to happen
In C# Asp.Net
.net 2.0 framework
If the above is not possible I do not mind looking into javascript alternatives.
If you can help it would be greatly appreciated.
You can use Group Validation. You can assign a validator a validationgroup value, and then explicitly validate that group, which can contain 1 or more validators.
Page.Validate("MyGroup");
You can also check the validation status of each validator explicitly using IsValid property, assuming validation has already taken place.
According this article:
function ValidatorValidate(val, validationGroup, event)
With jquery validators:
And in case I wanted to force the validation I should have written:
ValidatorValidate($("#<%= valEncOtherMimeTypeRequired.ClientID %>")[0]);
I'm new to C# MVC and I'm trying to add some dynamic validation checks to my view models that are used in a form. For example, I have a string property called FirstName. I can add the attribute StringLength(10) and Required() to it.
My problem is, depending on some other field, the FirstName StringLength could vary from 10 to 20, etc. I still want to use the MVC validations but be able to modify it. I know that attributes are bound to the class so maybe I'm using the wrong thing.
I want the abilities for attribute validation but have it modifiable at run time. Is this possible?
The values in an attribute have to be literals. You can still use attribute based validation, but you will need to use the CustomValidation tag and point it at a method to use. If it depends on multiple fields in the object, you will want to put this on the class rather than the property.
It seems you can add validation attributes at runtime by implementing DataAnnotationsModelValidatorProvider:
Dynamic Attributes # forums.asp.net
I want to write a custom ValidationAttribute that checks if the given value is unique or not.
The problem is that in the edit screen, it is not guaranteed that the user actually changed the value, resulting in a false error.
Is there a way to check in my attribute whether the value actually changed? Or can I trigger the attribute only when the value has changed?
I'm getting the feeling this requirement maybe just doesn't belong in an attribute?
When you say ValidationAttibute, do you mean using DataAnnotations? If so, then all of this applies, else, sorry, I misunderstood and only part of this will.
I think your best bet is to do this in the repository or BLL using your unique key for the record, at least this is how I did it. Get the previous values of the record and see if they changed. If they did change, then run your uniqueness checks.
If you can get this logic into the ValidationAttribute, then more power to you, but I am not sure if a validationAttribute would be the best thing since there are ways to get around them. From my understanding of these attributes, you should use them as supplements only to business logic validations and not as the only way that you validate your model.
See here for more info on DataAnnotations
EDIT:
Fair enough, now let's see if I can give an answer to help you :) Check out this link, it is the code for uniqueness checking on any property in any table. Pretty in-depth LINQ to SQL stuff, but looks like it works well. You should be able to decorate any property with this just like using the <Required> or <StringLenght> attributes.
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