Currently I have an IActionFilter that accepts a List<T> as parameter. In that action method I examine the posted viewmodel values. It looks something like this:
[HttpPost]
public async Task<IActionResult> SavePage(List<BaseField> fields)
{
for (var i = 0; i < fields.Count; i++)
{
if (fields[i].Type == "bb")
{
var inputObj = new InputConfigViewModel();
await TryUpdateModelAsync(inputObj, $"fields[{i}]");
}
if (fields[i].Type == "ee")
{
var tObj = new TextareaConfigViewModel();
await TryUpdateModelAsync(tObj, $"fields[{i}]");
}
}
return RedirectToAction("Index", "Dashboard");
}
This works so far. But I would like to abstract this code away to a custom ModelBinder class.
public class BaseFieldModelBinder : IModelBinder
{
public Task BindModelAsync(ModelBindingContext bindingContext)
{
// Need access to "List<BaseField> fields"...
return Task.CompletedTask;
}
}
How can I get access the List<BaseField> fields values in my ModelBinder, like I can from the action method in my Controller?
Custom model binders work on objects and not generic lists. You cannot access the all list inside the binder, but you can access each individual object.
With this said, I don't believe you can abstract the code, because you don't have the ControllerContext you need to access the FormCollection inside the binder context, neither to execute the TryUpdateModelAsync call in order to get extra information from form post that is not present on the List<BaseField>. You just have the ModelBindingContext.
If you still want to try, you have a good working example here.
Here is the relevant part, where you can get the reference of the object:
// Try to fetch the value of the argument by name
var valueProviderResult = bindingContext.ValueProvider.GetValue(modelName);
if (valueProviderResult == ValueProviderResult.None)
{
return TaskCache.CompletedTask;
}
bindingContext.ModelState.SetModelValue(modelName, valueProviderResult);
var value = valueProviderResult.FirstValue;
// Check if the argument value is null or empty
if (string.IsNullOrEmpty(value))
{
return TaskCache.CompletedTask;
}
Related
Update I have saved my problem a long time ago. The problem was that I was trying to call the view model on the wrong view method! I was calling the base view method (Document), instead of one of it's derived method (like NewDocument, PDFDocument, etc.) Thus it was only giving me the Documents data, which didn't change. I was looking and using the wrong view method all the time... Stephen, when you asked me
"Why do you create derived classes in a method but then return only the base class"
I couldn't answer the question at the time because I didn't even know myself, until I remember that originally, the method wasn't returning the base class. I only changed it so that it can work with the base view method, which was wrong in the first place!
That's what I get for only getting 3-4 hours of sleep in 3 days. Everything works right now. Thanks.
I'm having a hard time trying to figure out why the data in my view isn't changing after I do a post. Originally I was doing it via return View() and it worked, but since it was a partial view, the page didn't look great, so I was reading up and saw that it was better to do it by Post-Redirect-Get pattern (PRG) and to use an id value to retrieve the values instead of sending the entire model via Tempdata. I even used ModelState.Clear() and that didn't even work. When I debugged the code, the model only has the values from when I first called it.
Here's part of my Get controller:
NewDocument Get Controller
[DocumentAuthenticationFilter]
public ActionResult NewDocument(int? id = null)
{
// This doesn't work. The view keeps on showing the data from View(Services.CreateNewDocument()).
if (id != null)
{
return View(Services.GetdocumentViewModelData(DocEnum.Section.NEW_DOC_INDEX, (int)id));
}
// This works fine
return View(Services.CreateNewDocument());
}
And here's the post that calls the redirect:
NewDocument Post controller
[HttpPost]
[ValidateAntiForgeryToken]
[MultipleButton(Name = "action", Argument = "AddDocuments")]
//[OutputCache(Duration = 30, VaryByParam = "*")]
public ActionResult AddDocumentViewModel(FormCollection frm, DocumentViewModel dvm)
{
try
{
if (ModelState.IsValid)
{
int? DocID = Services.AddingNewDocument(dvm);
// See, I even tried to clear it.
ModelState.Clear();
return base.RedirectToAction("NewDocument", new { id = DocID });
}
else
{
// Display errors in the modal
}
return base.RedirectToAction("NewDocument");
}
And here's the old way I did it:
NewDocument Post controller
[HttpPost]
[ValidateAntiForgeryToken]
[MultipleButton(Name = "action", Argument = "AddDocuments")]
//[OutputCache(Duration = 30, VaryByParam = "*")]
public ActionResult AddDocumentViewModel(FormCollection frm, DocumentViewModel dvm)
{
try
{
if (ModelState.IsValid)
{
Services.AddingNewDocument(ref dvm);
dvm.NewRecordMode = DocEnum.Action.UPDATE;
// It worked, but only the partial view showed, and not the entire view.
return PartialView("_NewDocument", dvm);
}
else
{
// Display errors in the model
}
return base.RedirectToAction("NewDocument");
}
Could it be because I'm using a custom model binding?
My Custom Model Binding
public class BaseClassModelBinder : DefaultModelBinder
{
public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
{
var modelType = bindingContext.ModelType;
var modelTypeValue = controllerContext.Controller.ValueProvider.GetValue("ViewModel");
if (modelTypeValue == null)
throw new Exception("View does not contain the needed derived model type name");
var modelTypeName = modelTypeValue.AttemptedValue;
var type = modelType.Assembly.GetTypes().SingleOrDefault(x => x.IsSubclassOf(modelType) && x.Name == modelTypeName);
if (type == null)
{
throw new Exception(String.Format("Derived model type {0} not found", modelTypeName));
}
var instance = bindingContext.Model ?? base.CreateModel(controllerContext, bindingContext, type);
bindingContext.ModelMetadata = ModelMetadataProviders.Current.GetMetadataForType(() => instance, type);
return base.BindModel(controllerContext, bindingContext);
}
}
EDIT: And here's the GetDocumentViewModelData code:
GetDocumentFromViewModelData
public static DocumentViewModel GetDocumentViewModelData(DocEnum.Section docType, int id)
{
switch (docType)
{
case DocEnum.Section.NEW_DOCUMENT_INDEX:
// NewDocumentTypeViewModel is a child to DocumentTypeViewModel
DocumentTypeViewModel nd = NewDocumentService.GetViewModelByID(id);
return nd;
case DocEnum.Section.PDF_DOCUMENT:
DocumentTypeViewModel pdfvm = PDFDocumentService.GetViewModelByID(id);
return pdfvm;
case DocEnum.Section.XLS_DOCUMENT:
DocumentTypeViewModel xlsvm = XLSDocumentService.GetViewModelByID(id);
return xlsvm;
}
return null;
}
Edit: Also adding the GetViewModelByID function
GetViewModelByID
public static DocumentTypeViewModel GetViewModelByID(int id)
{
docEntities db = new docEntities();
NewDocumentTypeViewModel vm = new NewDocumentTypeViewModel();
// Calls a stored procedure called Select_Documents_ByID(id) to get the note entry
// that was submitted.
List<Select_Documents_ByID_Result> prevNotes = db.Select_Documents_ByID(id).ToList();
StringBuilder sNotes = new StringBuilder();
foreach (var note in prevNotes)
{
sNotes.AppendFormat("{0} - {1}: {2}\n\n", note.CreatedDate.ToString("yyyy-MM-dd HH:mm"), note.username, note.Entry);
}
vm.PreviousNotes = sNotes.ToString();
return vm;
}
Edit: I did a direct creation of the view model inside the Get controller, and it's the same result. when i debugged the view itself, the values from the new view model don't show up. Instead, the values from the initial view model, View(Services.CreateNewDocument()), shows.
[DocumentAuthenticationFilter]
public ActionResult NewDocument(int? id = null)
{
// Right here I created the view model to test thing, but I'm getting the same results. Nothing has changed.
if (id != null)
{
var d = new NewDocumentTypeViewModel(1, "Help!");
// This property is from the base class, DocumentTypeViewModel
d.DocumentTitle = "Testing!";
return View(d);
// Inside the view itself, none of the values in the view model, including the one
// belonging to the base class. It still shows the initial values.
}
// This works fine
// Or maybe not...
return View(Services.CreateNewDocument());
}
Edit: I wanted to see if it was also doing the same thing for the initial call to the view return View(Services.CreateNewDocument()), and decided to change the value for documentTitle in the base class from New Document to a randomly-generated number, after the object has been created.
Here's the code for DocumentTypeViewModel's default constructor:
public DocumentTypeViewModel()
{
DocumentTitle = "New Document";
NewRecordMode = DocEnum.Action.ADD;
DocumentID = 0;
}
And here's the Services.CreateNewDocument() code where I change the DocumentTitle after the View Model has been created.
public DocumentTypeViewModel CreateNewDocument()
{
DocumentTypeViewModel dtvm = new DocumentTypeViewModel();
Random r = new Random();
dtvm.DocumentTitle = r.Next(5, Int32.MaxValue).ToString();
return dtvm;
}
Now in the View, when I call DocumentTitle:
<div class="label-text-group">
#Html.LabelFor(model => model.DocumentTitle)
#Html.EditorFor(model => model.DocumentTitle)
</div>
You would expect to see a randomly-generated number every time the View gets called. Nope, what you would see is "New Document". Weird.
It's seems that Services.GetDocumentViewModelData() is not exactly working correctly. It only carries the values created by the base class' constructor when a view is created, not any values that have been added or changed within GetDocumentViewModelData() itself. Why is that? What's going on? Please help anybody!
I have solved it. Look at the Update section on top. Thanks Stephen.
We're using ASP.Net Web API to generate a feed and it includes the ability to do paging.
myfeed.com/afeed?page=2
My boss says "let's also allow users to use 'paged', because that's what WP uses." In addition, we're also using pageIndex in some of our older feeds. So what I'd like to do is accept all three.
myfeed.com/afeed?page=2
myfeed.com/afeed?paged=2
myfeed.com/afeed?pageIndex=2
I'd like to do is be able to write a clean Web API method, such as
public Foo Get(int page = 1)
{
//do some stuff
return foo;
}
without cluttering the method with page 'plumbing'. So I tried creating an ActionFilter
public override void OnActionExecuting(HttpActionContext actionContext)
{
object pageParam = new object(); //query["page"]
if (pageParam == null)
{
var altPageParam = GetPageParamUsingAlternateParams(actionContext);
if (altPageParam != null){}
//SetPageParam here
}
base.OnActionExecuting(actionContext);
}
private object GetPageParamUsingAlternateParams(HttpActionContext actionContext)
{
object result = new object();
object pageIndexParam = new object(); //Query["pageIndex"]
object pagedParam = new object(); ////Query["paged"]
if (pagedParam != null)
result = pagedParam;
else if (pageIndexParam != null)
result = pageIndexParam;
return result;
}
I didn't finish. As I was looking for the best way to get the query params, I stumbled into a big mistake!
OnActionExecuting is executed after int page = 1. Sure, I could override it in an ActionFilter, but that would lead to confusion down the road. I really want to be able to do a simple flow through the URI query parameters that goes from
page -> paged -> pageIndex -> default value in method
I have found a lot of articles on custom binding to a an object. Also, I found articles about "parameter binding", however those dealt with FromUri and FromBody. I didn't find anything that I felt had a direct parallel to what I'm facing.
You could achieve what you want by defining 3 different GET method with parameters matched with the query segment of the Url like the code snippet below:
public class ProductsController : ApiController
{
//Matched api/products?page=1
public IHttpActionResult Get(int page)
{
return GetPagedData(page);
}
//Matched api/products?paged=1
public IHttpActionResult GetPaged(int paged)
{
return GetPagedData(paged);
}
//Matched api/products?pagIndex=1
public IHttpActionResult GetPageIndex(int pageIndex)
{
return GetPagedData(pageIndex);
}
//Do the real paging here
private IHttpActionResult GetPagedData(int page =1)
{
return Ok("Data Pages");
}
}
I don't know if this is the right way to approach something, but I'm hoping it is. The example below is a heavy controller and is absolutely the wrong approach, but it get's the idea of what I'm looking for across.
public class PeopleController : Controller
{
public ActionResult List(string? api)
{
MyViewModel Model = new MyViewModel();
if (api == "json") {
// I'd like to return the Model as JSON
} else if (api == "XML") {
// I'd like to return the Model as XML
} else {
return View(Model);
}
}
}
Now what I need to be able to do is return the Model to the View if it's being requested like this:
http://example.com/People/List
But I'd like it to output JSON if it's requested like this:
http://example.com/People/List/?api=json
Or output XML if it's requested like this:
http://example.com/People/List/?api=xml
Is this just plain wrong? If not, what is the best approach to achieve this?
I was thinking of achieving it with a Custom MultiPurposeResult that could do all the filtering for me and then return it as this
public class PeopleController : Controller
{
public MultiPurposeResult List(string? api)
{
MyViewModel Model = new MyViewModel();
return MultiPurpose(Model); }
}
}
Agree with #Matt. Don't explicitly ask for the response type, infer it from the contentType in the request, which is more RESTful.
For example, created a basic enum type to encapsulate the response types you want:
public enum RestfulResultType
{
Json,
Html,
Xml
}
Then create a custom model binder than sets this property in your action, depending on the content type.
Then your controller could look like this:
public ActionResult List(RestfulResultType resultType)
{
var data = repo.GetSomeData();
switch (resultType)
{
case RestfulResultType.Json:
return Json(data);
case RestfulResultType.Xml:
return XmlResult(data); // MvcContrib
case RestfulResultType.Html:
return View(data);
}
}
If you need any more customization than the regular helpers provide, then create custom ActionResult's.
You can leave the return type as ActionResult - that's the point, so that the controller can return different formats.
ResfulResultTypeModelBinder.cs:
public class ResfulResultTypeModelBinder: IModelBinder
{
public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
{
if (controllerContext.HttpContext.Request.ContentType == "application/json")
return RestfulResultType.Json;
// other formats, etc.
}
}
Global.asax:
ModelBinders.Binders.Add(typeof(RestfulResultType), new RestfulResultTypeModelBinder());
You can create a custom MultiPurposeResult but I personally would lose the string? api from the method signature, instead have the MultiPurpose look for the presence of Request["format"] and then make the determination of what format to possible output the results in. Since the format doesn't nessecarily have anything to do with the ActionResult but more the format of the response.
An application permits users to create records. For our purposes, let's call those records Goals.
One user should not be able to see Goals created by another user.
What is the best method for preventing UserA from accessing UserB's Goal?
I can do it like this:
//using asp.net membership
Guid uId = (Guid)System.Web.Security.Membership.GetUser().ProviderUserKey;
//goal records contain a foreign key to users, so I know who owns what
Goal theGoal = db.Goals.SingleOrDefault(g => g.GoalId == goalId
&& g.UserId == uId);
if (null == theGoal)
{
ViewData["error"] = "Can't find that goal.";
return View("Error");
}
else
{
return View(theGoal);
}
This works fine. The problem is that I've got similar code littered in every action that accesses goals.
Is there a more re-usable way of accomplishing this?
I thought of implementing it as an Authorization Filter. 2 problems with that scheme:
1) Requires the filter to know about and use the DB.
2) Requires 2 queries(1 in the filter, another in the action) instead of just the 1 query in the action that I have now.
What's a more DRY way of accomplishing this?
A custom model binder is a great place to do this:
public class GoalModelBinder : DefaultModelBinder
{
private readonly IGoalRepository _repository;
public GoalModelBinder(IGoalRepository repository)
{
_repository = repository;
}
protected override object CreateModel(ControllerContext controllerContext, ModelBindingContext bindingContext, Type modelType)
{
// Here the default model binder does his job of binding stuff
// like the goal id which you would use in the repository to check
var goal = base.CreateModel(controllerContext, bindingContext, modelType) as Goal;
var user = controllerContext.HttpContext.User;
var theGoal = _repository.GetGoal(user, goal);
if (theGoal == null)
{
throw new HttpException(403, "Not authorized");
}
// It's OK, we've checked that the Goal belongs to the user
// => return it
return theGoal;
}
}
and then in your Application_Start register this model binder:
// some implementation of your repo
var sqlRepo = new SqlGoalRepository();
ModelBinders.Binders.Add(typeof(Goal), new GoalModelBinder(sqlRepo));
Now your controller action becomes less littered:
[Authorize]
public ActionResult Edit(Goal goal)
{
// if we get that far we are fine => we've got our goal
// and we are sure that it belongs to the currently logged user
return View(goal);
}
I have an action that returns either a FileContentResult or a NotModifiedResult, which is a custom result type that returns HTTP 304 to indicate that the requested resource has not been modified, like this:
[ReplaceMissingPicture(Picture = "~/Content/Images/nothumbnail.png", MimeType = "image/png")]
public ActionResult Thumbnail(int id)
{
var item = Service.GetItem(id);
var requestTag = Request.Headers["If-None-Match"] ?? string.Empty;
var tag = Convert.ToBase64String(item.Version.ToArray());
if (tag == requestTag)
{
return new NotModifiedResult();
}
if (item.Thumbnail != null)
{
var thumbnail = item.Thumbnail.ToArray();
var mime = item.PictureMime;
Response.AppendHeader("ETag", tag);
return File(thumbnail, mime);
}
else
{
return null;
}
}
This action needs to access the Response object, which is of course not present during testing, so that makes this action untestable. I could add conditional statements around it, so that it runs during testing, but then I can't test for the headers being set correctly.
What would be a solution to this problem?
FYI, the ReplaceMissingPicture filter returns a specific resource in case null was returned from this action, to keep the MapPath() call out of the controller for the very same reason.
The first step would be to create an interface which simplifies the services you need:-
public interface IHeaders
{
public string GetRequestHeader(string headerName);
public void AppendResponseHeader(string headerName, string headerValue);
}
Now create a default implementation:-
public Headers : IHeaders
{
public string GetRequestHeader(string headerName)
{
return HttpContext.Current.Request[headerName];
}
public void AppendResponseHeader(string headerName, string headerValue)
{
HttpContext.Current.Response.AppendHeader(headerName, headerValue);
}
}
Now add a new field to your Controller:-
private IHeaders myHeadersService;
add new constructor to you controller:-
public MyController(IHeaders headersService)
{
myHeadersService = headersService;
}
modify or add the default constructor:-
public MyController()
{
myHeadersService = new Headers();
}
now in your Action code use myHeadersService instead of the Response and Request objects.
In your tests create your own implementation of the IHeaders interface to emulate/test the Action code and pass that implementation when constructing the Controller.
How about creating a subclass of FileResult--say ETagFileResult--that in its ExecuteResult() method sets the ETag header, and then defaults to the base class implementation? You can test that class with a mocked context (as you presumably are with your NotModifiedResult) to be sure that it's doing the right thing. And remove the entire complication from the testing of the controller.
Failing that, it's possible to set a mocked context on the controller in your test (after instantiating the class, before calling the action method). See this question, for instance. But that seems like more work.
(Also, by the way, it looks like you're quoting the tag value twice there: once when tag is set, and once more when you actually set the header....)