I want a user to be able to query GET /api/mycontroller?enums=ABC
without using commas for the enums parameter. I know I can pass a comma separated parameter but using it without commas returns 'ABC' is not a valid value for type MyEnum. In my database, this field is stored as combination of characters without a comma. Is there a custom model binding attribute I can use and add it to the EnumVal property in MyRequest?
public enum MyEnum
{
A=1,
B=2,
C=4
}
public class MyRequest
{
public MyEnum EnumVal {get; set;}
}
[HttpGet("mycontroller")]
public async Task<ActionResult> MyController([FromQuery] MyRequest request)
{
//query db for row containing resuest.myEnum string combination...
// ...
}
I've looked into overriding the ValidationAttribute but it still returns an error response.
Fix the name of the action, since controller is a reserved word, you can not use it for the action name, and add enums input parameter
public async Task<ActionResult> My([FromQuery] MyRequest request, [FromQuery] string enums)
I was able to figure it out using a custom model binder
public class MyEnumTypeEntityBinder : IModelBinder
{
public Task BindModelAsync(ModelBindingContext bindingContext)
{
if (bindingContext == null)
{
throw new ArgumentNullException(nameof(bindingContext));
}
var modelName = bindingContext.ModelName;
// Try to fetch the value of the argument by name
var valueProviderResult = bindingContext.ValueProvider.GetValue(modelName);
if (valueProviderResult == ValueProviderResult.None)
{
return Task.CompletedTask;
}
int len = valueProviderResult.FirstValue.Length;
string query = valueProviderResult.FirstValue;
char[] charlist = query.ToCharArray( );
string enumConversionString = string.Join(",", charlist);
if (!Enum.TryParse(enumConversionString, out MyEnum model))
{
bindingContext.ModelState.TryAddModelError(modelName, string.Format("{0} is not a valid value for type {1}", valueProviderResult.FirstValue, modelName));
return Task.CompletedTask;
}
bindingContext.Result = ModelBindingResult.Success(model);
return Task.CompletedTask;
}
}
and adding the attribute above the MyEnum request prop:
[ModelBinder(BinderType = typeof(MyEnumTypeEntityBinder))]
public MyEnum? Type { get; set; }
public enum MyEnum
{
A=1,
B=2,
C=4
}
Related
I use some Enum as parameter in some action. For example we have the following code
public enum SomeEnum { SomeVal1 = 1, SomeVal2 = 2 }
[HttpGet]
public void SomeAction(SomeEnum someParameter) { }
By default asp.net engine allows to use both string and integer values that's why we are able to call it like this 'http://host/SomeController/SomeAction/SomeVal1' or this 'http://host/SomeController/SomeAction/1' or even this 'http://host/SomeController/SomeAction/54'! I would like to stay with the first sample using string value. For this I've implemented the following model binder:
public class RequireStringsAttribute : ModelBinderAttribute
{
public RequireStringsAttribute() : base(typeof(ModelBinder))
{
}
private class ModelBinder : IModelBinder
{
public Task BindModelAsync(ModelBindingContext bindingContext)
{
var value = bindingContext.ValueProvider.GetValue(bindingContext.FieldName).FirstValue;
var isValid = Enum.GetNames(bindingContext.ModelType).Any(name =>
name.Equals(value, StringComparison.OrdinalIgnoreCase));
if (isValid)
{
bindingContext.Result = ModelBindingResult.Success(Enum.Parse(bindingContext.ModelType, value, ignoreCase: true));
}
else
{
bindingContext.ActionContext.ModelState.AddModelError(bindingContext.FieldName, $"The value '{value}' is not valid.");
}
return Task.CompletedTask;
}
}
}
And I've applied it:
[HttpGet]
public void SomeAction([RequireStrings]SomeEnum someParameter) { }
It works fine but I just want to know is there a better way to do it?
I have property in my PersonDTO class:
[EmailAddress]
public string Email { get; set; }
It works fine, except I want to allow empty strings as values for my model, if I send JSON from client side:
{ Email: "" }
I got 400 bad request response and
{"$id":"1","Message":"The Email field is not a valid e-mail address."}
However, it allows omitting email value:
{ FirstName: "First", LastName: 'Last' }
I also tried:
[DataType(DataType.EmailAddress, ErrorMessage = "Email address is not valid")]
but it does not work.
As far as I understood, Data Annotations Extensions pack does not allow empty string either.
Thus, I wonder if there is a way to customize the standard EmailAddressAttribute to allow empty strings so I do not have to write custom validation attribute.
You have two options:
Convert string.Empty to null on the Email field. Many times that is perfectly acceptable. You can make this work globally, or by simply making your setter convert string.Empty to null on the email field.
Write a custom EmailAddress attribute, since EmailAddressAttribute is sealed you can wrap it and write your own forwarding IsValid method.
Sample:
bool IsValid(object value)
{
if (value == string.Empty)
{
return true;
}
else
{
return _wrappedAttribute.IsValid(value);
}
}
Expansion on option 1 (from Web Api not converting json empty strings values to null)
Add this converter:
public class EmptyToNullConverter : JsonConverter
{
private JsonSerializer _stringSerializer = new JsonSerializer();
public override bool CanConvert(Type objectType)
{
return objectType == typeof(string);
}
public override object ReadJson(JsonReader reader, Type objectType,
object existingValue, JsonSerializer serializer)
{
string value = _stringSerializer.Deserialize<string>(reader);
if (string.IsNullOrEmpty(value))
{
value = null;
}
return value;
}
public override void WriteJson(JsonWriter writer, object value,
JsonSerializer serializer)
{
_stringSerializer.Serialize(writer, value);
}
}
and use on the property:
[JsonConverter(typeof(EmptyToNullConverter))]
public string EmailAddress {get; set; }
or globally in WebApiConfig.cs:
config.Formatters.JsonFormatter.SerializerSettings.Converters.Add(
new EmptyToNullConverter());
It's Easy. Do This. Bye
private string _Email;
[EmailAddress(ErrorMessage = "Ingrese un formato de email válido")]
public string Email { get { return _Email; } set { _Email = string.IsNullOrWhiteSpace(value) ? null : value; } }
I used the suggestion from Yishai Galatzer to make a new ValidationAttribute called EmailAddressThatAllowsBlanks:
namespace System.ComponentModel.DataAnnotations
{
public class EmailAddressThatAllowsBlanks : ValidationAttribute
{
public const string DefaultErrorMessage = "{0} must be a valid email address";
private EmailAddressAttribute _validator = new EmailAddressAttribute();
public EmailAddressThatAllowsBlanks() : base(DefaultErrorMessage)
{
}
public override bool IsValid(object value)
{
if (string.IsNullOrEmpty(value.ToString()))
return true;
return _validator.IsValid(value.ToString());
}
}
}
Set TargetNullValue property of the binding to an empty string.
TargetNullValue=''
I've seen a lot of similar posts on this, but haven't found the answer specific to controller parameters.
I've written a custom attribute called AliasAttribute that allows me to define aliases for parameters during model binding. So for example if I have: public JsonResult EmailCheck(string email) on the server and I want the email parameter to be bound to fields named PrimaryEmail or SomeCrazyEmail I can "map" this using the aliasattribute like this: public JsonResult EmailCheck([Alias(Suffix = "Email")]string email).
The problem: In my custom model binder I can't get a hold of the AliasAttribute class applied to the email parameter. It always returns null.
I've seen what the DefaultModelBinder class is doing to get the BindAttribute in reflector and its the same but doesn't work for me.
Question: How do I get this attribute during binding?
AliasModelBinder:
public class AliasModelBinder : DefaultModelBinder
{
public static ICustomTypeDescriptor GetTypeDescriptor(Type type)
{
return new AssociatedMetadataTypeTypeDescriptionProvider(type).GetTypeDescriptor(type);
}
public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
{
var value = base.BindModel(controllerContext, bindingContext);
var descriptor = GetTypeDescriptor(bindingContext.ModelType);
/*************************/
// this next statement returns null!
/*************************/
AliasAttribute attr = (AliasAttribute)descriptor.GetAttributes()[typeof(AliasAttribute)];
if (attr == null)
return null;
HttpRequestBase request = controllerContext.HttpContext.Request;
foreach (var key in request.Form.AllKeys)
{
if (string.IsNullOrEmpty(attr.Prefix) == false)
{
if (key.StartsWith(attr.Prefix, StringComparison.InvariantCultureIgnoreCase))
{
if (string.IsNullOrEmpty(attr.Suffix) == false)
{
if (key.EndsWith(attr.Suffix, StringComparison.InvariantCultureIgnoreCase))
{
return request.Form.Get(key);
}
}
return request.Form.Get(key);
}
}
else if (string.IsNullOrEmpty(attr.Suffix) == false)
{
if (key.EndsWith(attr.Suffix, StringComparison.InvariantCultureIgnoreCase))
{
return request.Form.Get(key);
}
}
if (attr.HasIncludes)
{
foreach (var include in attr.InlcludeSplit)
{
if (key.Equals(include, StringComparison.InvariantCultureIgnoreCase))
{
return request.Form.Get(include);
}
}
}
}
return null;
}
}
AliasAttribute:
[AttributeUsage(AttributeTargets.Parameter | AttributeTargets.Class, AllowMultiple = false, Inherited = true)]
public class AliasAttribute : Attribute
{
private string _include;
private string[] _inlcludeSplit = new string[0];
public string Prefix { get; set; }
public string Suffix { get; set; }
public string Include
{
get
{
return _include;
}
set
{
_include = value;
_inlcludeSplit = SplitString(_include);
}
}
public string[] InlcludeSplit
{
get
{
return _inlcludeSplit;
}
}
public bool HasIncludes { get { return InlcludeSplit.Length > 0; } }
internal static string[] SplitString(string original)
{
if (string.IsNullOrEmpty(original))
{
return new string[0];
}
return (from piece in original.Split(new char[] { ',' })
let trimmed = piece.Trim()
where !string.IsNullOrEmpty(trimmed)
select trimmed).ToArray<string>();
}
}
Usage:
public JsonResult EmailCheck([ModelBinder(typeof(AliasModelBinder)), Alias(Suffix = "Email")]string email)
{
// email will be assigned to any field suffixed with "Email". e.g. PrimaryEmail, SecondaryEmail and so on
}
Gave up on this and then stumbled across the Action Parameter Alias code base that will probably allow me to do this. It's not as flexible as what I started out to write but probably can be modified to allow wild cards.
what I did was make my attribute subclass System.Web.Mvc.CustomModelBinderAttribute which then allows you to return a version of your custom model binder modified with the aliases.
example:
public class AliasAttribute : System.Web.Mvc.CustomModelBinderAttribute
{
public AliasAttribute()
{
}
public AliasAttribute( string alias )
{
Alias = alias;
}
public string Alias { get; set; }
public override IModelBinder GetBinder()
{
var binder = new AliasModelBinder();
if ( !string.IsNullOrEmpty( Alias ) )
binder.Alias = Alias;
return binder;
}
}
which then allows this usage:
public ActionResult Edit( [Alias( "somethingElse" )] string email )
{
// ...
}
I want to have possibility to access action by the following URL type:
http://localhost/MyControllerName/MyActionName/Id1+Id2+Id3+Id4 etc.
and handle it in code in the following way:
public ActionResult MyActionName(string[] ids)
{
return View(ids);
}
+ is a reserved symbol in an url. It means white space. So to achieve what you are looking for you could write a custom model binder:
public class StringModelBinder : DefaultModelBinder
{
public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
{
var value = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
if (value != null && !string.IsNullOrEmpty(value.AttemptedValue))
{
return value.AttemptedValue.Split(' ');
}
return base.BindModel(controllerContext, bindingContext);
}
}
and then either register it globally for the string[] type or use the ModelBinder attribute:
public ActionResult MyActionName(
[ModelBinder(typeof(StringModelBinder))] string[] ids
)
{
return View(ids);
}
Obviously if you want to use an url of the form /MyControllerName/MyActionName/Id1+Id2+Id3+Id4 that will bind the last part as an action parameter called ids you will have to modify the default route definition which uses {id}.
After all chose the following solution:
public ActionResult Action(string id = "")
{
var ids = ParseIds(id);
return View(ids);
}
private static int[] ParseIds(string idsString)
{
idsString = idsString ?? string.Empty;
var idsStrings = idsString.Split(new[] { ' ', '+' });
var ids = new List<int>();
foreach (var idString in idsStrings)
{
int id;
if (!int.TryParse(idString, out id))
continue;
if (!ids.Contains(id))
ids.Add(id);
}
return ids.ToArray();
}
I have created a custom validation attribute by subclassing ValidationAttribute. The attribute is applied to my viewmodel at the class level as it needs to validate more than one property.
I am overriding
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
and returning:
new ValidationResult("Always Fail", new List<string> { "DateOfBirth" });
in all cases where DateOfBirth is one of the properties on my view model.
When I run my application, I can see this getting hit. ModelState.IsValid is set to false correctly but when I inspect the ModelState contents, I see that the Property DateOfBirth does NOT contain any errors. Instead I have an empty string Key with a value of null and an exception containing the string I specified in my validation attribute.
This results in no error message being displayed in my UI when using ValidationMessageFor. If I use ValidationSummary, then I can see the error. This is because it is not associated with a property.
It looks as though it is ignoring the fact that I have specified the membername in the validation result.
Why is this and how do I fix it?
EXAMPLE CODE AS REQUESTED:
[AttributeUsage(AttributeTargets.Class, AllowMultiple = false, Inherited = true)]
public class ExampleValidationAttribute : ValidationAttribute
{
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
// note that I will be doing complex validation of multiple properties when complete so this is why it is a class level attribute
return new ValidationResult("Always Fail", new List<string> { "DateOfBirth" });
}
}
[ExampleValidation]
public class ExampleViewModel
{
public string DateOfBirth { get; set; }
}
hello everybody.
Still looking for solution?
I've solved the same problem today. You have to create custom validation attribute which will validate 2 dates (example below). Then you need Adapter (validator) which will validate model with your custom attribute. And the last thing is binding adapter with attribute. Maybe some example will explain it better than me :)
Here we go:
DateCompareAttribute.cs:
[AttributeUsage(AttributeTargets.Class, AllowMultiple = true, Inherited = true)]
public class DateCompareAttribute : ValidationAttribute
{
public enum Operations
{
Equals,
LesserThan,
GreaterThan,
LesserOrEquals,
GreaterOrEquals,
NotEquals
};
private string _From;
private string _To;
private PropertyInfo _FromPropertyInfo;
private PropertyInfo _ToPropertyInfo;
private Operations _Operation;
public string MemberName
{
get
{
return _From;
}
}
public DateCompareAttribute(string from, string to, Operations operation)
{
_From = from;
_To = to;
_Operation = operation;
//gets the error message for the operation from resource file
ErrorMessageResourceName = "DateCompare" + operation.ToString();
ErrorMessageResourceType = typeof(ValidationStrings);
}
public override bool IsValid(object value)
{
Type type = value.GetType();
_FromPropertyInfo = type.GetProperty(_From);
_ToPropertyInfo = type.GetProperty(_To);
//gets the values of 2 dates from model (using reflection)
DateTime? from = (DateTime?)_FromPropertyInfo.GetValue(value, null);
DateTime? to = (DateTime?)_ToPropertyInfo.GetValue(value, null);
//compare dates
if ((from != null) && (to != null))
{
int result = from.Value.CompareTo(to.Value);
switch (_Operation)
{
case Operations.LesserThan:
return result == -1;
case Operations.LesserOrEquals:
return result <= 0;
case Operations.Equals:
return result == 0;
case Operations.NotEquals:
return result != 0;
case Operations.GreaterOrEquals:
return result >= 0;
case Operations.GreaterThan:
return result == 1;
}
}
return true;
}
public override string FormatErrorMessage(string name)
{
DisplayNameAttribute aFrom = (DisplayNameAttribute)_FromPropertyInfo.GetCustomAttributes(typeof(DisplayNameAttribute), true).SingleOrDefault();
DisplayNameAttribute aTo = (DisplayNameAttribute)_ToPropertyInfo.GetCustomAttributes(typeof(DisplayNameAttribute), true).SingleOrDefault();
return string.Format(ErrorMessageString,
!string.IsNullOrWhiteSpace(aFrom.DisplayName) ? aFrom.DisplayName : _From,
!string.IsNullOrWhiteSpace(aTo.DisplayName) ? aTo.DisplayName : _To);
}
}
DateCompareAttributeAdapter.cs:
public class DateCompareAttributeAdapter : DataAnnotationsModelValidator<DateCompareAttribute>
{
public DateCompareAttributeAdapter(ModelMetadata metadata, ControllerContext context, DateCompareAttribute attribute)
: base(metadata, context, attribute) {
}
public override IEnumerable<ModelValidationResult> Validate(object container)
{
if (!Attribute.IsValid(Metadata.Model))
{
yield return new ModelValidationResult
{
Message = ErrorMessage,
MemberName = Attribute.MemberName
};
}
}
}
Global.asax:
protected void Application_Start()
{
// ...
DataAnnotationsModelValidatorProvider.RegisterAdapter(typeof(DateCompareAttribute), typeof(DateCompareAttributeAdapter));
}
CustomViewModel.cs:
[DateCompare("StartDateTime", "EndDateTime", DateCompareAttribute.Operations.LesserOrEquals)]
public class CustomViewModel
{
// Properties...
public DateTime? StartDateTime
{
get;
set;
}
public DateTime? EndDateTime
{
get;
set;
}
}
I am not aware of an easy way fix this behavior. That's one of the reasons why I hate data annotations. Doing the same with FluentValidation would be a peace of cake:
public class ExampleViewModelValidator: AbstractValidator<ExampleViewModel>
{
public ExampleViewModelValidator()
{
RuleFor(x => x.EndDate)
.GreaterThan(x => x.StartDate)
.WithMessage("end date must be after start date");
}
}
FluentValidation has great support and integration with ASP.NET MVC.
When returning the validation result use the two parameter constructor.
Pass it an array with the context.MemberName as the only value.
Hope this helps
<AttributeUsage(AttributeTargets.Property Or AttributeTargets.Field, AllowMultiple:=False)>
Public Class NonNegativeAttribute
Inherits ValidationAttribute
Public Sub New()
End Sub
Protected Overrides Function IsValid(num As Object, context As ValidationContext) As ValidationResult
Dim t = num.GetType()
If (t.IsValueType AndAlso Not t.IsAssignableFrom(GetType(String))) Then
If ((num >= 0)) Then
Return ValidationResult.Success
End If
Return New ValidationResult(context.MemberName & " must be a positive number", New String() {context.MemberName})
End If
Throw New ValidationException(t.FullName + " is not a valid type. Must be a number")
End Function
End Class
You need to set the ErrorMessage property, so for example:
public class DOBValidAttribute : ValidationAttribute
{
private static string _errorMessage = "Date of birth is a required field.";
public DOBValidAttribute() : base(_errorMessage)
{
}
//etc......overriding IsValid....