Attribute routing with string parameters is ambiguous - asp.net-mvc

I am getting the error
the current request is ambiguous between the following action methods:
System.Web.Mvc.ActionResult Foo1(System.String) on type
Project.Web.Controllers.PageController
System.Web.Mvc.ActionResult Foo2(System.String) on type
Project.Web.Controllers.PageController
The a href calling the ActionResults are
Foo1
Foo2
I am basically passing the string instead of a int id ( I realise this is not the best way to do this , but that is not the issue i want to address here )
This allows me to add a string parameter to the Routing for clean urls, so my ActionResult is now
[AllowAnonymous, Route("{page}")]
public ActionResult Foo1(string page)
{
...
}
and
[AllowAnonymous, Route("{page}")]
public ActionResult Foo2(string page)
{
...
}
Why is there ambiguity when the links are being passed to different ActionResults and the parameters are different?

You seem to be misunderstanding what the [Route] attribute does. Your example is definitely ambiguous.
This:
[AllowAnonymous, Route("{page}")]
means "map this action to any path that has one and only one segment, and treat that segment as the page parameter.
So all of these URLs:
http://example.com/Foo1
http://example.com/Foo2
http://example.com/SomethingElse
would be mapped to the action that has that attribute.
If you have two actions with that same route, then the MVC framework doesn't know which action to map the URL to. Both of them are valid candidates.
I think there is a simpler way to implement what you are trying to do.
In RouteConfig.cs, add a route map that doesn't include the controller name in the URL pattern:
routes.MapRoute(
name: "Pages",
url: "{action}",
defaults: new { controller = "Page", action = "Index", id = UrlParameter.Optional }
);
Add an action parameter to your actions:
[AllowAnonymous]
public ActionResult Foo1(string action)
{
// action has the value Foo1
...
}
and
[AllowAnonymous]
public ActionResult Foo2(string action)
{
// action has the value Foo2
...
}
Remove the page stuff from your links:
Foo1
Foo2
And you should be all set.
Edit: If you just want to allow passing in a dynamic value for page, then you can get rid of the Foo1 and Foo2 actions, and just have one action:
[Route("{page=index}")]
public ActionResult Page(string page)
{
// page is the value specified in the url
}
For links within the site, just use ordinary <a> elements:
To Foo1
To Foo2
and I think that should do it.

Related

Url.Action generates query instead of parameter URL

This is the controller class. I am showing only method signatures.
[Authorize]
[RoutePrefix("specification")]
[Route("{action=index}")]
public class SpecificationController : BaseController
{
[HttpGet]
[Route("~/specifications/{subcategoryID?}")]
public ActionResult Index(int? subcategoryID);
[HttpPost]
[Route("get/{subcategoryID?}")]
public JsonResult Get(int? subcategoryID);
[HttpGet]
[Route("~/specifications/reorder/{subcategoryID}")]
public ActionResult Reorder(int subcategoryID);
[HttpGet]
[Route("new/{id?}")]
public ActionResult New(int? id);
[HttpGet]
[Route("edit/{id?}")]
public ActionResult Edit(int id);
[HttpPost]
[ValidateAntiForgeryToken]
[Route("edit")]
public JsonResult Edit(SpecificationJson specification);
[HttpPost]
[Route("moveup")]
public JsonResult MoveUp(int specificationID);
[HttpPost]
[Route("movedown")]
public JsonResult MoveDown(int specificationID);
[HttpDelete]
[Route]
public ActionResult Delete(int id);
}
The problem is that calling
#Url.Action("index", "specifications", new RouteValueDictionary() { { "subcategoryID", #subcategory.SubcategoryID } })
returns
/specifications?subcategoryID=15
instead of
/specifications/15
Why is this happening? I do not have any similar methods on that route expect this one!
Your call to generate the URL is incorrect. To match the controller name, it should be "specification" not "specifications".
#Url.Action("index", "specification", new { subcategoryID=subcategory.SubcategoryID })
Keep in mind, the URL specified in the [Route] attribute is only cosmetic. Your route values must match the controller name and action method name for it to utilize that route to generate the URL.
To make this more clear for those maintaining the code (and slightly faster), it might be better to make the parameter values Pascal case just like the controller and action names.
#Url.Action("Index", "Specification", new { subcategoryID=subcategory.SubcategoryID })
Why is this happening?
-------------------------------------------------------------
| Route Key | Route Value | Your Action Request |
|--------------------|---------------|----------------------|
| Controller | Specification | Specifications | No Match
| Action | Index | Index | Match
| subcategoryID | ? | XXX | Match (Always)
-------------------------------------------------------------
To get a route match, all parameters of #Url.Action must match the route value dictionary. The problem is that Controller=Specifications is not defined in the route value dictionary because your actual controller's name is SpecificationController. Therefore, the route value name is Specification regardless of what you put in the [Route] attribute. The URL ~/specifications/{subcategoryID?} has nothing at all to do with an outgoing (URL generation) match - it only matches incoming URLs and determines what the URL will look like when it is generated.
If you want to use Specifications instead of Specification for the route value, you need to move the action method to a new controller named SpecificationsController. That said, I don't see what difference it makes, since the end user won't see the route value name anyway.
You have to use this in order to generate follow url: /specifications/15
#Url.Action("index", "specifications", new { subcategoryID=subcategory.SubcategoryID })
[Route("~/specifications/{subcategoryID?}")]
public ActionResult Index(int? subcategoryID);
What did I do wrong and how can I revert to using subcategoryID as
parameter name ?
You have to add another route (before DEFAULT ROUTE) in order to have another optional parameter:
Something like this:
routes.MapRoute(
"SecondRoute",
"{controller}/{action}/{subcategoryID}",
defaults: new { controller = "Home", action = "Index", subcategoryID = UrlParameter.Optional }
);

Possible workaround to have multiple http get methods two actions with same name?

I am using asp.net MVC 4. Is there a way to use two http get methods on an action with the same name but different parameters? Or just a way to have the page be an index page for both so the name of the page is consistent? Also, int cannot be null.
Example:
Used for querystring and searches
[HttpGet]
public ActionResult Index(int num, string aString)
{
}
Used for just an action link click(a default search)
[HttpGet]
public ActionResult Index()
{
}
No work-around. What you can do is following:
[HttpGet]
public ActionResult Index(int num, string aString)
{
//if num == null, throw exception or do something
// if string == null, do something, if not, do something else
}
- (Html . BeginForm ( "ViewName", "ControllerName", FormMethod.Get ) {
Html . Hidden ( "actionname1", "true" ) form elements set 1 submit
button 1 }
(Html . BeginForm ( "ViewName", "ControllerName", FormMethod.Get ) {
Html . Hidden("actionname2", "true") form elements set 2 submit
button 2 }
In Controller, check for "true "values for actionname1, actionname2
and decide on control flow for each. Assumption: Same View and Same
Controller WITH Two distinct FormMethod.Gets
..Paurav
What I actually end up doing was passing in an object with nullable values in one get http request action. As #Display Name suggested above in the comment Microsoft has this functionality built into the .net framework.

overload views in MVC?

I want to have links http://localhost:2409/Account/Confirmation/16 and that link http://localhost:2409/Account/Confirmation/ (without parametr). But with this action methods, it isn't working. Why?
public ActionResult Confirmation(int id, string hash)
{
Some code..
return View();
}
second, I just want to return View, if parametr is empty.
public ActionResult Confirmation()
{
return View();
}
Error (translated):
The current request for action on a controller Confirmation
AccountController is ambiguous between the following methods of
action: System.Web.Mvc.ActionResult Confirmation (Int32,
System.String) for type TC.Controllers.AccountController
System.Web.Mvc.ActionResult Confirmation () for type
TC.Controllers.AccountController
You cannot have multiple actions with the same name using the same HTTP verb (in your case GET.) You can name your actions differently but this means the link will change or you can use different VERB but this can also leads to other problems like you cannot just enter the link in your browser.
What you should do is to change your id to be optional with int? and merge your two actions into one:
public ActionResult Confirmation(int? id, string hash)
{
if(id.HasValue)
{
//Some code.. using id.Value
return View();
}
//There was no Id given
return View();
}
You may also need to allow in your route that the id is optional. If you are using the default routes this should be the default setting:
routes.MapRoute(
"Default", // Route name
"{controller}/{action}/{id}", // URL with parameters
new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);
There is no need to make 2-methods for it. Your HTTP request get confused that which ActionMethod should be called on both cases;
http://localhost:2409/Account/Confirmation/16
http://localhost:2409/Account/Confirmation/
Instead of all this, just create a single method. Make its parameter optional or assign some default value to the parameters. Here are 2-examples to understand it.
// 1. Default value to paramter
public ActionResult Confirmation(int id = 0, string hash = null)
{
//Some code..
return View();
}
// 2. Make id optional
public ActionResult Confirmation(int? id, string hash)
{
//Some code..
return View();
}
You can adopt any one approach from them.

overload action for number of parameters in asp.net mvc

Is it possible to overload the action methods based on number of parameters in request?
Eg:
1.
domain.com/List/Filter/ByName
invokes -> public ActionResult Filter(string criteria1)
2.
domain.com/List/Filter/ByName/ByRanking
invokes -> public ActionResult Filter(string criteria1, string criteria2)
I'm using asp.net mvc2.
Action methods cannot be overloaded based on parameters because there would be no reasonable way to disambiguate a URL into multiple overloaded methods.
What you can do, though is either this:
public ActionResult Filter(string criteria1, string criteria2)
and then check whether criteria2 is null to filter only by name.
Alternatively, you can use ActionNameAttribute to decorate your action methods
[ActionName("FilterByName")]
public ActionResult Filter(string criteria1)
[ActionName("FilterByNameAndRanking")]
public ActionResult Filter(string criteria1, string criteria2)
and then use that name in route registration. This approach, however, can lead to much confusion.
If I'm not mistaken the best way to do this would be to add two different controller methods and map them to two different Urls.
public ActionResult Filter1(string criteria1);
public ActionResult Filter2(string criteria1, criteria2);
Then you have two route definitions:
This will map this URL List/Filter/xxCriteria/ to the first controller
routes.MapRoute(
"Filter", // Route name
"{controller}/Filter/{criteria1}", // URL with parameters
new { controller = "List", action = "Filter1", criteria="" } // Parameter defaults
);
This will map this URL List/Filter/xxCriteriaName/xxxCriteriaRank to the second controller. Without this route you could still map a url to the second method, but it would look like : List/Filter/?criteria1=xx&criteria2=xx
routes.MapRoute(
"Filter2", // Route name
"{controller}/Filter/{criteria1}/{criteria2}", // URL with parameters
new { controller = "List", action = "Filter2", criteria1 = "", criteria2 = "" } // Parameter defaults
);
Hope it helped.

QueryString id parameter not being used

I've got a very basic ASP.Net MVC project where I'd like to use a parameter name of id on one of my controller actions. From everything I've read that shouldn't be a problem but for some reason using a parameter name of id fails to get the value extracted from the query string but if I change it to any other different name it will work.
I only have a single route in my global.asx
routes.MapRoute(
"Default", // Route name
"{controller}/{action}/{id}", // URL with parameters
new { controller = "Home", action = "Index", id = "" } // Parameter defaults
);
My controller method is:
public ActionResult Confirm(string id)
{
....
}
A URL of http://mysite/customer/confirm/abcd works. A URL of http://mysite/customer/confirm?id=abcd fails.
If I change the controller method to:
public ActionResult Confirm(string customerID)
{
....
}
then a URL of http://mysite/customer/confirm?customerID=abcd works.
Is there something special about using "id" as a parameter in an ASP.Net MVC query string?
Update: Changed id from 1234 to abcd, my id's are actually strings.
If you do not apply an id parameter (either querystring or POST), the system just ignores it, and you can remove the "id" parameter in your controller:
public ActionResult Confirm()
In your case, you would just stick with the id parameter. Why make an ugly customerID parameter, when id is "mapped" automatically?
This is an easy and simple example of the use of id parameter.
public ActionResult Confirm(int? id)
{
if (id.HasValue && id.Value > 0) // check the id is actually a valid int
_customerServer.GetById(id.Value);
// do something with the customer
return View();
}
This works too, for me. We're doing it in our application right now with a standard route:
public ActionResult Confirm(string id)
{
if (!string.IsNullOrEmpty(id)) // check the id is actually a valid string
_customerServer.GetByStringId(id);
// do something with the customer
return View();
}
If you need to have id in query string, then don't create route with 'id' parameter.
In case you have route "{controller}/{action}" then you can use public ActionResult Confirm(string id) as your controller method.
Routes don't care about query strings.

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