I'm developing a little ERP to my company and I crashed into a problem about validation:
I have self property object like:
public class Person
{
[Required]
public string Name { get; set; }
public int Phone { get; set; }
public bool HasContact { get; set; }
public Person Contact { get; set; }
}
If HasContact is false, I don`t want put a Contact. If is true, I want.
The problem is my ModelState never is Valid, because Name is Required and Contact self implement Person.
I would like to set condition if HasContact is true, my application try validate the Contact property. If is not, set Valid and execute controller correct.
Is it possible or am I crazy?
You should have your object implement IValidatableObject. It lets you implement your own validation logic so you can ignore properties as necessary (see this SO question).
Your code might be something like this:
public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
{
var results = new List<ValidationResult>();
if (this.HasContact)
{
Validator.TryValidateProperty(this.Contact,
new ValidationContext(this, null, null) { MemberName = "Contact" },
results);
}
return results;
}
Related
I'm creating an application using ASP.NET Core and Entity Framework. I have two models:
class Book
{
public int Id { get; set; }
public string Name { get; set; }
public List<Author> Authors { get; set; }
}
class Author
{
public int Id { get; set; }
public string Name { get; set; }
public Book Book { get; set; }
}
I want that when creating an author, his name cannot be created the same as the book. I want to add validation to Author.Name (Something like this: Author.Name != Book.Name.
Also, I want this rule to enter into the db too. So I think it possible to make in DbContext (OnModelCreating).
How can I do it? Thanks a lot!
Your Author class can implement the IValidatableObject interface.
This way, you will have a Validate method like this:
public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
{
if (Author.Name == Book.Name)
{
yield return new ValidationResult(
$"Author name and Book name can't have the same value.",
new[] { nameof(Name) });
}
}
Then, you can manage the ModelState validation in your controller action as something like:
if (!ModelState.IsValid)
{
// Do something when validation is not ok
}
To prevent this to be commited on database side, it would be better to ensure the data consitency on database side by implementing a check constraint directly in SQL on your Author table.
I have following object
public class TestClass
{
[Required]
public int TestId { get; set; }
}
I validate using:
List<ValidationResult> results = new List<ValidationResult>();
var vc = new ValidationContext(data);
if (Validator.TryValidateObject(data, vc, results, true))
return;
This validates perfectly fine if data is of type TestClass but not when I pass list of TestClass items (List<TestClass>)
How can I validate the items withing a list without iterating?
TryValidateObject expects an object and not a list of. You have to write a helper class. Furthermore it even doesn't recursively check the Validation. See this SO question for more...
Usually I add the Validate method in the class that I need to validate, and I foreach the property that has a list of T.
For example:
public class ClassToValidate : IValidatableObject
{
// Property with a non-custom type
[Required(AllowEmptyStrings = false, ErrorMessage = "\"Language\" is required. It can not be empty or whitespace")]
public string Language { get; set; }
// Property with a custom type
public Source Source { get; set; }
// Property with a custom type list
public List<Streaming> StreamingList { get; set; } = new List<Streaming>();
// Validate method that you need to implement because of "IValidatableObject"
public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
{
// The validation result that will be returned
List<ValidationResult> result = new List<ValidationResult>();
// Language doesn't need to be added in the Validate method because it isn't a custom object
// Custom single T object to be validated
Validator.TryValidateObject(Source, new ValidationContext(Source), result, true);
// Custom list<T> object to be validated
foreach (var streaming in StreamingList)
{
Validator.TryValidateObject(streaming, new ValidationContext(streaming), result, true);
}
return result;
}
}
public class Source
{
[Range(16, 192, ErrorMessage = "\"Bitrate\" must be between 16 and 192")]
public int? Bitrate { get; set; }
public string Codec { get; set; }
}
public class Streaming
{
[Required(AllowEmptyStrings = false, ErrorMessage = "\"Url\" can not be empty")]
public string Url { get; set; }
[Range(0, 1000, ErrorMessage = "\"Offset\" must be between 0 and 1000")]
public int Offset { get; set; }
}
I'm trying to leverage the DataAnnotations.Validator outside of MVC. I have two services that validate their respective models. Both models inherit from a Base class I wrote that had a ValidateModel() method.
public class BaseValidatableDomainModel : IValidatableDomainModel
{
public BaseValidatableDomainModel()
{
ModelState = new ModelStateDictionary();
}
public ModelStateDictionary ModelState { get; set; }
public virtual void ValidateModel()
{
var validationContext = new ValidationContext(this, serviceProvider: null, items: null);
var results = new List<ValidationResult>();
Validator.TryValidateObject(this, validationContext, results);
foreach (var thisInvalidResult in results)
{
ModelState.AddModelError(thisInvalidResult.MemberNames.FirstOrDefault(),thisInvalidResult.ErrorMessage);
}
}
}
I have a test for each service that verifies the service behaves correctly when the data is invalid. The one model correctly errors for PhoneNumber == null:
[Required]
public string PhoneNumber { get; set; }
However, the other model does not error when CompanyId is 0. CompanyId is defined as this:
public class CompanyAddressDomainModel : BaseValidatableDomainModel
{
// Other fields
[Required]
[Range(1, int.MaxValue, ErrorMessage = "Company is required")]
public int CompanyId { get; set; }
[Required]
public AddressInputDomainModel Address { get; set; }
}
The code calls validation like this:
CompanyAddressDomainModel companyAddress = // set values
companyAddress.ValidateModel();
if (!companyAddress.ModelState.IsValid)
{
return companyAddress;
}
Why would it catch some validation, and not others? As far as I can tell, the two services and models are defined the same. If more information is needed, please let me know.
If I test with CompanyId == 0 and Address == null I do see the address error, but not the CompanyId error.
Looks like I have to tell TryValidateObject to validate all.
public static bool TryValidateObject(
object instance,
ValidationContext validationContext,
ICollection<ValidationResult> validationResults,
bool validateAllProperties
)
Like this:
Validator.TryValidateObject(this, validationContext, results, true);
Is there any way of using data annotations to compare two form field (eg. to confirm an email address) are the same, before allowing the form to be posted?
eg. can the regular expression data annotation use the match function to reference another property in a ViewModel?
Use the CompareAttribute
public string EmailAddress {get; set;}
[Compare(nameof(EmailAddress), ErrorMessage = "Emails mismatch")]
public string VerifiedEmailAddress { get; set; }
As one possibe option self-validation:
Implement an interface IValidatableObject with method Validate, where you can put your validation code.
public class TestModel : IValidatableObject
{
public string Email{ get; set; }
public string ConfirmEmail { get; set; }
public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
{
if (Email != ConfirmEmail)
{
yield return new ValidationResult("Emails mismatch", new [] { "ConfirmEmail" });
}
}
}
Please notice: this is only server-side validation.
I have a Model with 4 properties which are of type string. I know you can validate the length of a single property by using the StringLength annotation. However I want to validate the length of the 4 properties combined.
What is the MVC way to do this with data annotation?
I'm asking this because I'm new to MVC and want to do it the correct way before making my own solution.
You could write a custom validation attribute:
public class CombinedMinLengthAttribute: ValidationAttribute
{
public CombinedMinLengthAttribute(int minLength, params string[] propertyNames)
{
this.PropertyNames = propertyNames;
this.MinLength = minLength;
}
public string[] PropertyNames { get; private set; }
public int MinLength { get; private set; }
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
var properties = this.PropertyNames.Select(validationContext.ObjectType.GetProperty);
var values = properties.Select(p => p.GetValue(validationContext.ObjectInstance, null)).OfType<string>();
var totalLength = values.Sum(x => x.Length) + Convert.ToString(value).Length;
if (totalLength < this.MinLength)
{
return new ValidationResult(this.FormatErrorMessage(validationContext.DisplayName));
}
return null;
}
}
and then you might have a view model and decorate one of its properties with it:
public class MyViewModel
{
[CombinedMinLength(20, "Bar", "Baz", ErrorMessage = "The combined minimum length of the Foo, Bar and Baz properties should be longer than 20")]
public string Foo { get; set; }
public string Bar { get; set; }
public string Baz { get; set; }
}
Self validated model
Your model should implement an interface IValidatableObject. Put your validation code in Validate method:
public class MyModel : IValidatableObject
{
public string Title { get; set; }
public string Description { get; set; }
public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
{
if (Title == null)
yield return new ValidationResult("*", new [] { nameof(Title) });
if (Description == null)
yield return new ValidationResult("*", new [] { nameof(Description) });
}
}
Please notice: this is a server-side validation. It doesn't work on client-side. You validation will be performed only after form submission.
ExpressiveAnnotations gives you such a possibility:
[Required]
[AssertThat("Length(FieldA) + Length(FieldB) + Length(FieldC) + Length(FieldD) > 50")]
public string FieldA { get; set; }
To improve Darin's answer, it can be bit shorter:
public class UniqueFileName : ValidationAttribute
{
private readonly NewsService _newsService = new NewsService();
public override bool IsValid(object value)
{
if (value == null) { return false; }
var file = (HttpPostedFile) value;
return _newsService.IsFileNameUnique(file.FileName);
}
}
Model:
[UniqueFileName(ErrorMessage = "This file name is not unique.")]
Do note that an error message is required, otherwise the error will be empty.
Background:
Model validations are required for ensuring that the received data we receive is valid and correct so that we can do the further processing with this data. We can validate a model in an action method. The built-in validation attributes are Compare, Range, RegularExpression, Required, StringLength. However we may have scenarios wherein we required validation attributes other than the built-in ones.
Custom Validation Attributes
public class EmployeeModel
{
[Required]
[UniqueEmailAddress]
public string EmailAddress {get;set;}
public string FirstName {get;set;}
public string LastName {get;set;}
public int OrganizationId {get;set;}
}
To create a custom validation attribute, you will have to derive this class from ValidationAttribute.
public class UniqueEmailAddress : ValidationAttribute
{
private IEmployeeRepository _employeeRepository;
[Inject]
public IEmployeeRepository EmployeeRepository
{
get { return _employeeRepository; }
set
{
_employeeRepository = value;
}
}
protected override ValidationResult IsValid(object value,
ValidationContext validationContext)
{
var model = (EmployeeModel)validationContext.ObjectInstance;
if(model.Field1 == null){
return new ValidationResult("Field1 is null");
}
if(model.Field2 == null){
return new ValidationResult("Field2 is null");
}
if(model.Field3 == null){
return new ValidationResult("Field3 is null");
}
return ValidationResult.Success;
}
}
Hope this helps. Cheers !
References
Code Project - Custom Validation Attribute in ASP.NET MVC3
Haacked - ASP.NET MVC 2 Custom Validation
A bit late to answer, but for who is searching.
You can easily do this by using an extra property with the data annotation:
public string foo { get; set; }
public string bar { get; set; }
[MinLength(20, ErrorMessage = "too short")]
public string foobar
{
get
{
return foo + bar;
}
}
That's all that is too it really. If you really want to display in a specific place the validation error as well, you can add this in your view:
#Html.ValidationMessage("foobar", "your combined text is too short")
doing this in the view can come in handy if you want to do localization.
Hope this helps!