I am working on an MVC project where controller actions deal with Assets. Different controllers take in the assetId parameter in different way: Some controllers simply get int assetId, other int id, and other using a complex object AssetDTO dto (which contains a property that holds the assetId)
I am writing an ActionFilter that is added to the action method and is provided with the actionParameter name where I can get the asset value.
Action Method:
[AssetIdFilter("assetId")]
public ActionResult Index(int assetId)
{
...
}
The attribute is defined as:
public class AssetIdFilterAttribute : ActionFilterAttribute
{
public string _assetIdParameterKey { get; set; }
public AssetIdFilterAttribute (string assetIdParameterKey)
{
_assetIdParameterKey = assetIdParameterKey;
}
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
int assetId;
if (Int32.TryParse(filterContext.ActionParameters[_assetIdParameterKey].ToString(), out assetId))
{
......
}
}
This works as expected, but will only work when the assetId is provided as a primitive. I am not sure what to do when the assetId is provided within a complex object into the action method.
Will I need to parse each object differently depending on the type? I am hoping I can specify some kind of dot-notation in the AssetIdFilter to tell it where the assetId is located: dto.assetId
Any way I can use dynamics? or reflection?? ect.???
and here dynamic comes to the rescue.you can change the actionFilterAttribute to be :
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
dynamic assetIdHolder = filterContext.ActionParameters[_assetIdParameterKey];
if (assetIdHolder.GetType().IsPrimitive)
{
//do whatever with assetIdHolder
}
else
{
//do whatever with assetIdHolder.assetId
}
}
cheers!
Well, yes, you answered your question. One way would be to use dot notation:
//simple case:
[AssetId("id")]
public ActionResult Index(string id) {
//code here
}
//complex case:
[AssetId("idObj", AssetIdProperty = "SubObj.id")]
public ActionResult index(IdObject idObj) {
//code here
}
And AssetIdAttribute is as follows:
public class AssetIdAttribute : ActionFilterAttribute
{
public string _assetIdParameterKey { get; set; }
public string AssetIdProperty { get; set; }
public AssetIdFilterAttribute(string assetIdParameterKey)
{
_assetIdParameterKey = assetIdParameterKey;
}
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
int assetId;
var param = filterContext.ActionParameters[_assetIdParameterKey];
int.TryParse(GetPropertyValue(param, this.AssetIdProperty).ToString(), out assetId);
//you code continues here.
}
private static string GetPropertyValue(object souce, string property)
{
var propNames = string.IsNullOrWhiteSpace(property) || !property.Contains('.') ? new string[] { } : property.Split('.');
var result = souce;
foreach (var prop in propNames)
{
result = result.GetType().GetProperty(prop).GetValue(result);
}
return result.ToString();
}
}
The code does not have null checks when calling ToString and when calling GetProperty though. Also, it does not check the success of TryParse. Please apply these corrections when used.
Maybe this code could be written using dynamic, but at the end dynamic usage is compiled into object using reflection (something like what I have done here), thus no big difference to me.
Also, maybe it would be more clear to have a parameter like "idObj.SubObj.id", but that again depends on the preference, and the code will become a little bit more complex.
Related
So Basically i wrote a validator for my class with FluentValidation and also a filter to do the validation task for me in my webAPI project, so far it's OK but assume that my User class has firstname,lastname,email,password properties
and i have two routes (one for register and the other one for login)
and as you might have noticed required properties are different on these route.
Thus,should I really need to write individual validation for each and every action i have?because this makes a lot of code code duplication and it's hard to change.is there any way to just add required condition based on the request coming with single validation class?
Any suggestion???
A better practice would be to use a factory pattern for your validations and use a an action filter to short circuit bad requests. You could validate any action argument(Headers, Request Bodies, etc..) with something like this.
public class TestValidationAttribute : Attribute, IActionFilter
{
private string _requestModelName;
public TestValidationAttribute(string requestModelName)
{
_requestModelName = requestModelName;
}
public void OnActionExecuting(ActionExecutingContext context)
{
// using Microsoft.Extensions.DependencyInjection;
var services = context.HttpContext.RequestServices;
var accessor = services.GetService<IHttpContextAccessor>();
var factory = services.GetService<ITestValidatorFactory>();
var tokens = accessor.HttpContext.GetRouteData().DataTokens;
if (!tokens.TryGetValue("RouteName", out var routeNameObj))
{
throw new Exception($"Action doesn't have a named route.");
}
var routeName = routeNameObj.ToString();
var validator = factory.Create(routeName);
if (!context.ActionArguments.TryGetValue(_requestModelName, out var model))
{
throw new Exception($"Action doesn't have argument named {_requestModelName}.");
}
TestModel test;
try
{
test = (TestModel) model;
}
catch (InvalidCastException)
{
throw new Exception($"Action argument can't be casted to {nameof(TestModel)}.");
}
var validation = validator.Validate(test);
if (!validation.Successful)
{
context.Result = new BadRequestObjectResult(validation.ResponseModel);
}
}
public void OnActionExecuted(ActionExecutedContext context)
{
}
}
public class TestController : Controller
{
[HttpPost]
[Route("Test/{id}", Name = "TestGet")]
[TestValidation("model")]
public IActionResult Test(TestModel model)
{
return Ok();
}
}
public class ValidationResult
{
public bool Successful { get; }
public ResponseModel ResponseModel { get; }
}
public class TestModel
{
}
public interface ITestValidator
{
ValidationResult Validate(TestModel model);
}
public interface ITestValidatorFactory
{
ITestValidator Create(string routeName);
}
In my code below I want to check with AttributeValidation if a field is given dependent on a property of its parent element. The comment in the class
RequiredIfParentState1
describes my question best.
public class ChildModel()
{
[RequiredIfParentState1]
public string ImRequired { get; set; }
}
public class ParentViewModel()
{
public int state { get; set; }
public ChildModel child = new ChildModel();
}
public class RequiredIfParentState1: ValidationAttribute, IClientModelValidator
{
RequiredIfParentState1()
{
}
void AddValidation(ClientModelValidationContext context)
{
}
protected override ValidationResult IsValid(object i_value, ValidationContext i_context)
{
var element = i_context.ObjectInstance;
if(i_value == null && //what do i have to put here to check if the state is 1?)
{
return new ValidationResult($"Field is Required in state 1.");
}
return ValidationResult.Success;
}
}
I feel this is the wrong approach.
An object being in a valid state is one thing (required fields and type checking), but handling business logic is a separate concern.
You could write a validation service, that examines the model in detail, checking business logic concerns, and build up a list of errors.
Where errors are found you can return these in your response.
I wanted to save notification in TempData and shown to user. I create extension methods for this and implement a class which Extends from ActionResult. I need to access TempData in override ExecuteResult method with ActionContext.
Extension Method:
public static IActionResult WithSuccess(this ActionResult result, string message)
{
return new AlertDecoratorResult(result, "alert-success", message);
}
Extends ActionResult class.
public class AlertDecoratorResult : ActionResult
{
public ActionResult InnerResult { get; set; }
public string AlertClass { get; set; }
public string Message { get; set; }
public AlertDecoratorResult(ActionResult innerResult, string alertClass, string message)
{
InnerResult = innerResult;
AlertClass = alertClass;
Message = message;
}
public override void ExecuteResult(ActionContext context)
{
ITempDataDictionary tempData = context.HttpContext.RequestServices.GetService(typeof(ITempDataDictionary)) as ITempDataDictionary;
var alerts = tempData.GetAlert();
alerts.Add(new Alert(AlertClass, Message));
InnerResult.ExecuteResult(context);
}
}
Call extension method from controller
return RedirectToAction("Index").WithSuccess("Category Created!");
I get 'TempData ' null , How can I access 'TempData' in 'ExecuteResult' method.
I was literally trying to do the exact same thing today (have we seen the same Pluralsight course? ;-) ) and your question led me to find how to access the TempData (thanks!).
When debugging I found that my override on ExecuteResult was never called, which led me to try the new async version instead. And that worked!
What you need to do is override ExecuteResultAsync instead:
public override async Task ExecuteResultAsync(ActionContext context)
{
ITempDataDictionaryFactory factory = context.HttpContext.RequestServices.GetService(typeof(ITempDataDictionaryFactory)) as ITempDataDictionaryFactory;
ITempDataDictionary tempData = factory.GetTempData(context.HttpContext);
var alerts = tempData.GetAlert();
alerts.Add(new Alert(AlertClass, Message));
await InnerResult.ExecuteResultAsync(context);
}
However, I have not fully understood why the async method is called as the controller is not async... Need to do some reading on that...
I find out the way to get the TempData. It need to get from ITempDataDictionaryFactory
var factory = context.HttpContext.RequestServices.GetService(typeof(ITempDataDictionaryFactory)) as ITempDataDictionaryFactory;
var tempData = factory.GetTempData(context.HttpContext);
I want to model an 'Expense' object that has a 'Sum' (decimal) field.
In the view, I want to validate that the user enters a positive value.
OTOH I want to make sure I save the object with a negative value in the DB.
Right now, the model looks like this:
//------The model-------
public class Operation {
[Range(typeof(decimal), "0.0001", "79228162514264337593543950335")]
public virtual decimal Sum { get; set; }
[...]
}
public class Expense : Operation
{
public override decimal Sum
{
get
{
return base.Sum;
}
set
{
base.Sum = - Math.Abs(value);
}
}
}
//------In the controller-------
[HttpPost]
public ActionResult CreateExpense(Expense operation, int[] SelectedTags)
{
return CreatePost(operation, SelectedTags);
}
private ActionResult CreatePost(Operation operation, int[] SelectedTags)
{
if (ModelState.IsValid) // <-- this fails
[...]
}
The problem is, the MVC validation works with the object's properties (not the POST'ed form values), sees the negative value and fails to validate.
What should I do to fix this?
It looks to me like I'm not separating concerns (validate user input vs maintain database integrity).
Should I use a view model to hold the user input and then populate the actual model from the view model? Doesn't sound like KISS...
I found out that specifying a separate validation attribute on the property of the inherited class works a treat.
Can't think of something more straight-forward.
Here's how the model looks like now:
public class Operation {
public virtual decimal Sum { get; set; }
}
public class Income : Operation
{
[Range(typeof(decimal), "0.0001", "79228162514264337593543950335")]
public override decimal Sum
{
get { return base.Sum; }
set { base.Sum = Math.Abs(value); }
}
}
public class Expense : Operation
{
[Range(typeof(decimal), "-79228162514264337593543950335", "-0.0001")]
public override decimal Sum
{
get { return base.Sum; }
set { base.Sum = - Math.Abs(value); }
}
}
A validation attribute to check if the value is less than zero is another simple solution.
public class PositiveNumberAttribute : ValidationAttribute
{
protected override ValidationResult IsValid(object number, ValidationContext validationContext)
{
return int.Parse(number.ToString()) >= 0
? ValidationResult.Success : new ValidationResult("Positive value required.");
}
}
Then apply to property
[PositiveNumber]
public virtual decimal Sum { get; set; }
I am fairly new to MVC, but after playing with it (MVC 3/Razor), I am hooked.
I have a few questions:
1) What is the best, or most widely used pattern to develop MVC apps in? Repository, DDD, UOW?
2) I am using the Entity Framework 4, so could some please explain to me or point me to a good source that will explain the Repository Pattern w/EF4? Doesn't EF4 take place as the business layer and the data access layer? Does the Repository Pattern even provide a benefit?
3) Also, one last question, could someone explain the whole relationship between the Controller, the Model and the View? I get the basics, but maybe a little more in depth of the correct way to use it. View Models - Say I have a view that displays customer info, and one that edits it, should I have a view model and an edit model, or can the be passed around?
4) Examples??
Thanks for the help up front,
$("Sam")
** EDIT **
Am I on the right track here:
Public Class HomeController
Inherits System.Web.Mvc.Controller
Function Index(ByVal id As Integer) As ActionResult
Return View(New HomeModel)
End Function
<HttpPost()> _
Function Index(ByVal Model As HomeModel) As ActionResult
Return View(Model)
End Function
End Class
Public Class HomeModel
Private _Repository As IRepository(Of Customer)
Public Property Customer As Customer
Public Sub New()
End Sub
Public Sub New(ByVal ID As Integer)
_Repository = New CustomerRepository
Customer = _Repository.GetByID(ID)
End Sub
End Class
Public Interface IRepository(Of T)
Function GetByID(ByVal ID As Integer) As T
Sub Add(ByVal Entity As T)
Sub Delete(ByVal Entity As T)
End Interface
Public Class CustomerRepository
Implements IRepository(Of Customer)
Public Sub Add(ByVal Entity As Customer) Implements IRepository(Of Customer).Add
End Sub
Public Sub Delete(ByVal Entity As Customer) Implements IRepository(Of Customer).Delete
End Sub
Public Function GetByID(ByVal ID As Integer) As Customer Implements IRepository(Of Customer).GetByID
Return New Customer With {.ID = ID, .FirstName = "Sam", .LastName = "Striano"}
End Function
End Class
Public Class Customer
Public Property ID As Integer
Public Property FirstName As String
Public Property LastName As String
End Class
I use generic repositories that get instantiated in a service class (using Dependency Injection with Ninject).
The service class essentially performs two functions:
It provides all the methods that the controller will consume.
It has a property called ViewModel, that essentially maps the data that the views need into a MyViewModel class.
The Controller consumes the service class. With this "pattern", your controllers look like:
namespace ES.eLearningFE.Areas.Courses.Controllers
{
public partial class CourseController : Controller
{
ICourseDisplayService service;
public CourseController(ICourseDisplayService service)
{
this.service = service;
}
public virtual ActionResult Display(int CourseId, int StepOrder, string PupilName, string TutorName)
{
service.CourseId = CourseId;
service.StepOrder = StepOrder;
service.PupilName = PupilName;
service.TutorName = TutorName;
if (Request.IsAjaxRequest())
{
return PartialView(service.ViewModel);
}
else
{
return View(service.ViewModel);
}
}
}
}
The ViewModel class only hold display data and no methods (except the odd really simple method to retrieve data from another property that is, for example a List<> object).
Works really well. An example of a service class:
namespace ES.eLearning.Domain.Services.Courses
{
public class SqlCourseDisplayService : ICourseDisplayService
{
DataContext db;
public SqlCourseDisplayService(DbDataContextFactory contextFactory)
{
db = contextFactory.Make();
CoursesRepository = new SqlRepository<Course>(db);
StepsRepository = new SqlRepository<CourseStep>(db);
StepLinksRepository = new SqlRepository<StepLink>(db);
UserCoursesRepository = new SqlRepository<UserCourse>(db);
CourseTutorsRepository = new SqlRepository<CourseTutor>(db);
UsersRepository = new SqlRepository<User>(db);
}
#region ICourseDisplayService Members
public ViewModels.CourseDisplayVM ViewModel
{
get
{
return new ViewModels.CourseDisplayVM
{
CourseId = this.CourseId,
CourseName = this.Course.Name,
Steps = this.Steps,
ActiveStepIndex = this.ActiveStepIndex,
CurrentStepIndex = this.CurrentStepIndex,
Pupil = new UserDto { UserId = this.PupilId, UserName = this.PupilName },
Tutors = this.GetTutors(this.CourseId),
Tutor = tutorName == null ? null : new UserDto { UserName = this.TutorName, UserId = this.TutorId}
};
}
}
#region Entities
int courseId;
public int CourseId
{
get
{
if (courseId == 0) throw new ApplicationException("Invalid Course Id!");
return courseId;
}
set
{
if (value == 0) throw new ApplicationException("Invalid Course Id!");
try
{
Course = (from c in CoursesRepository.Query where c.CourseId == value select c).First();
Steps = Course.CourseSteps.ToList();
courseId = value;
}
catch {throw new ApplicationException("No Course found for Course Id: " + value);}
}
}
public Data.Course Course { get; private set; }
public int StepOrder { get; set; }
public List<Data.CourseStep> Steps { get; private set; }
public int ActiveStepIndex
{
get
{
if (PupilName == null)
{
throw new ApplicationException("Pupil not set!");
}
if (CourseId == 0)
{
throw new ApplicationException("Course not set!");
}
try
{
var x = (from uc in UserCoursesRepository.Query where (uc.IdCourse == CourseId) && (uc.UserName == PupilName) select uc).First();
return x.ActiveStepIndex;
}
catch { throw new ApplicationException("Could not get Active Step!"); }
}
}
#endregion
#region Users
string tutorName;
public string TutorName
{
get
{
if (tutorName == null) throw new ApplicationException("Invalid call to get Tutor Name [Null Tutor Name]!");
return tutorName;
}
set
{
tutorName = value;
TutorId = (Guid)Membership.GetUser(tutorName).ProviderUserKey;
}
}
public Guid TutorId { get; set; }
string pupilName;
public string PupilName
{
get { return pupilName; }
set
{
pupilName = value;
PupilId = (Guid)Membership.GetUser(pupilName).ProviderUserKey;
}
}
public Guid PupilId { get; set; }
#endregion
#region Utility Properties
public int CurrentStepIndex { get; set; }
public int StepCount
{
get
{
return Steps == null ? 0 : Steps.Count();
}
}
#endregion
#region Private Utilities
private List<UserDto> GetTutors(int CourseId)
{
return (from ct in CourseTutorsRepository.Query join u in UsersRepository.Query
on ct.TutorName equals u.UserName
where (ct.CourseId == courseId)
select new UserDto { UserName = ct.TutorName, UserId = u.UserId }).ToList();
}
#endregion
#region Repositories
private IRepository<Course> CoursesRepository
{
get;
set;
}
private IRepository<CourseStep> StepsRepository
{
get;
set;
}
private IRepository<StepLink> StepLinksRepository
{
get;
set;
}
private IRepository<UserCourse> UserCoursesRepository
{
get;
set;
}
private IRepository<CourseTutor> CourseTutorsRepository
{
get;
set;
}
private IRepository<User> UsersRepository
{
get;
set;
}
#endregion
#endregion
}
}
May not be everyone's choice, but hey, it works for me... AND (more importantly) my clients and their users.
Edit
As requested in the comment below, the Repository that I use:
namespace ES.eLearning.Domain
{
public class SqlRepository<T> : IRepository<T> where T : class
{
DataContext db;
public SqlRepository(DataContext db)
{
this.db = db;
}
#region IRepository<T> Members
public IQueryable<T> Query
{
get { return db.GetTable<T>(); }
}
public List<T> FetchAll()
{
return Query.ToList();
}
public void Add(T entity)
{
db.GetTable<T>().InsertOnSubmit(entity);
}
public void Delete(T entity)
{
db.GetTable<T>().DeleteOnSubmit(entity);
}
public void Attach(T entity)
{
db.GetTable<T>().Attach(entity);
}
public void Save()
{
db.SubmitChanges();
}
#endregion
}
}
And the IRepository Interface:
namespace Wingspan.Web.Mvc
{
public interface IRepository<TEntity> where TEntity : class
{
List<TEntity> FetchAll();
IQueryable<TEntity> Query {get;}
void Add(TEntity entity);
void Delete(TEntity entity);
void Attach(TEntity entity);
void Save();
}
}
This should help you getting started. There are a lot of tutorials and videos available; for example:
Understanding Models, Views and Controllers
The ASP.NET MVC 2.0 basics and excellent introduction by Scott Hanselman. Personally one of my favorite speakers.
And also at www.asp.net; there are a few tutorials/examples to help you getting started. For example the Music Store sample
Unfortunately, I'm not so familiar with EF4/Repository pattern. But here's a blogpost about this pattern.
1) I would say that the repository pattern is the most widely used, then there is inversion of controll too.
2) I can't really point out the benefits with using a repository for entity framework other than that the controller should not know about how to acces data other then asking a repository. This makes it easy to switch it out sometime.
You can also eager load the data to make sure that the view don't call the database in every iteration of a foreach, for example a collection of users to display data from a child entity. You can probly do this anyway, but I feel that the repository is the right place to do it.
3) I can't tell you about the concept in a more in depth way, but I can tell some about viewmodels. In my opinion you should only use viewmodels if there is anything more then one entity you want to send to the view, for example a list of countries. You can alo use a viewmodel to "flatten" out very complex objects.
I would defiantly say the repository pattern is used a lot. This pattern can be used with Dependency Injection. Using Dependency Injection makes Unit Testing a breeze because you can snap different repositories to an abstract repoistory. Check out http://ninject.org/ for a simple to use Dependecy injector for .NET.
View Models should hold display data and transfer that data from the controller to the view. If you want to edit and display customer info, take a look at this