I get the following error when I click the Edit link from the List view
The parameters dictionary contains a null entry for parameter 'envId' of non-nullable type 'System.Int32' for method 'System.Web.Mvc.ActionResult Edit(Int32)' in 'WebUI.Controllers.EnvironmentsController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter.
Parameter name: parameters
Here is my code:
Summary.ascx
Routes
Env Controller, Edit Action methods
Env Controller, List Action method
EnvRepository and SqlEnvRepository
Your auto-generated links say this:
<td><%= Html.ActionLink("Edit", "Edit", new { id= Model.EnvironmentID} )%></td>
but the controller code says this:
public ActionResult Edit(int envId)
MVC's model binding hooks the parameters in the action up by name, and the default route assumes the first parameter will be an int called id. Change the name of your Edit() parameter to id and it should work.
Alternatively, you could change the ActionLink parameters object to new { envId = Model.EnvironmentID } but that will cause your URLs to look like this:
http://localhost/Env/Edit?envId = 1
instead of this:
http://localhost/Env/Edit/1
Related
On the Home View I'm generating a number of links:
<ul class="nav navbar-nav">
#foreach (var item in ViewBag.RegList)
{
<li>#Html.ActionLink((string)item.registryName, "Index", "Registry", new { item.registryName }, new { item.registryID }) </li>
}
</ul>
I don't get - how do I set params in ActionLink for my controller and where they go from there?
That's how I defined Index in me controller:
public async Task<ActionResult> Index(object attr)
But in attr goes only object, which when casted to string becomes null. If the orgignal type is string - then also null.
How do I transfer a parameter? Or I'm casting value to the wrong type?
Also I don't understand - what must fourth parameter of ActionLink (routeValues) be?
Method that I'm using: https://msdn.microsoft.com/en-us/library/dd504972(v=vs.108).aspx
Or this one: https://msdn.microsoft.com/en-us/library/dd493068(v=vs.108).aspx
If you look at the created link they will contain a set of query string parameters
"https://some.where/controller/SomeAction/7788?extraParam1=foo&extraParam2=bar"
The standard routing config of MVC makes the parameter "id" part of the local path ("7788" in the example), whereas additional parameters are added to the query string (after the question mark).
Your method signature to the action should be something like
public async Task<ActionResult>
SomeAction(string id, string extraParam1, string extraParam2)
to get the parameters in my example link.
I'm receiving the following error that my default route parameters are null. I've used this same code on a Controller Action that didn't have any parameters in the URL and it worked fine. I know that my custom route is being called but I don't understand why startIndex and pageSize are showing up null in the action.
Error:
The parameters dictionary contains a null entry for parameter 'startIndex' of non-nullable type 'System.Int32' for method 'System.Web.Mvc.ActionResult ViewVcByStatus(System.String, Int32, Int32)' in 'AEO.WorkOrder.WebUI.Controllers.VendorComplianceController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter.
Parameter name: parameters
Controller:
public ActionResult ViewVcByStatus(string status, int startIndex, int pageSize) { ... }
Route:
routes.MapRoute("ViewVcByStatus", "ViewVcByStatus/{status}",
new
{
controller = "VendorCompliance",
action = "ViewVcByStatus",
startIndex = 0,
pageSize = WebConfigurationManager.AppSettings["PageSize"],
});
Link:
<a href="VendorCompliance/ViewVcByStatus?status=PROCESSED">
Also tried this link which produces the same error:
<a href="VendorCompliance/ViewVcByStatus/PROCESSED">
Try this.
public ActionResult ViewVcByStatus(string status, int? pageSize, int?startIndex)
{
return View();
}
Route.config
routes.MapRoute(
name: "ViewVcByStatus",
url: "ViewVcByStatus/{status}",
defaults: new { controller = "VendorCompliance", action = "ViewVcByStatus", startIndex = UrlParameter.Optional, pageSize = UrlParameter.Optional });
optional parameters should be declared optional in routeconfig and mark them int? in your action method, This will do the work for you. Hope this helps.This solution will work with your url pattern in your question "http://localhost:53290/VendorCompliance/ViewVcByStatus?status=PROCESSED".
Send the startIndex and pageSize with the link(I hardcoded it, use parameters instead), your actionresult is expecting all parameters that the link needs to provide, and the MapRoute will probably fall through to default Route because it can´t match it with any other route matching the one parameter you provided
<a href="VendorCompliance/ViewVcByStatus?status=PROCESSED&startIndex=0&pageSize=0">
On my Index page I have the following link to the Details view:
#Html.ActionLink("Details", "Details", new { id = item.ClubId })|
My controller is expecting an int:
public ActionResult Details(int ClubId)
{
var club = _service.GetClub(ClubId);
var model = AutoMapper.Mapper.Map<ClubViewModel>(club);
return View(model);
}
Im getting this every time though:
The parameters dictionary contains a null entry for parameter 'ClubId'
of non-nullable type 'System.Int32' for method
'System.Web.Mvc.ActionResult Details(Int32)' in
'MyProject.Web.Controllers.ClubsController'. An optional
parameter must be a reference type, a nullable type, or be declared as
an optional parameter. Parameter name: parameters
I know this is something to do with routing however I have tried swapping UrlParameter.Optional to "" and making the ViewModel's ClubId nullable but the error remains.
If I rewire my controller to accept a Club object and pass in item from the Index view then everything is fine and the ClubId is populated in debug but I'm left with a stupidly large parameter list in the URL.
I don't really get what the problem is here?
Your controller is expecting a parameter named ClubId but you're passing a parameter called id. They need to match.
have you tried using ClubId instead of just id?
SOLUTION
the route
routes.MapRoute(
"Whatever", // Route name
"{controller}/{action}/{id}", //{ID} MUST BE USED IN YOUR CONTROLLER AS THE PARAMETER
new { controller = "MyController", action = "MyActionName", id = UrlParameter.Optional } // Parameter defaults
);
And that's it! I guess you must use the name of the id in the
public actionresult(int id //must be ID HERE like global.asax)
Steps to reproduce my problem:
1. Create a new mvc3 application
2. Go to home controller and put Index(int? x){ return view()}
3. Run the application
4. Go to the url type in the url http://localthost:someport/Home/Index/1
5. Insert a break point in controller to see the value of x
6. Notice that even if you put the url above x NOT equal to 1 as is suppose to!
I just dont understand why i am getting a null in the id....
public ActionResult MyActionName(int? id)
{
//the id is null!!!!!!!!!!!! event thought i just entered the url below!
}
I enter the following url in my browser
http://locahost/MyController/MyActionName/1
//I also put this in my global.asax but it doesnt really help.
routes.MapRoute(
"Whatever", // Route name
"{controller}/{action}/{id}", // URL with parameters
new { controller = "MyController", action = "MyActionName", id = UrlParameter.Optional } // Parameter defaults
);
AND!
My error if I put
public ActionResult MyActionName(int id)
{
//the id is null!!!!!!!!!!!! event thought i just entered the url below!
}
Note that the above example was made for simplicity this error is for the actual application.
Server Error in '/' Application.
The parameters dictionary contains a null entry for parameter 'MvrId' of non-nullable type 'System.Int32' for method 'System.Web.Mvc.ActionResult Index(Int32)' in 'MedicalVariance.Controllers.MedicineManagementController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter.
Parameter name: parameters
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.ArgumentException: The parameters dictionary contains a null entry for parameter 'MvrId' of non-nullable type 'System.Int32' for method 'System.Web.Mvc.ActionResult Index(Int32)' in 'MedicalVariance.Controllers.MedicineManagementController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter.
Parameter name: parameters
Make sure your route is defined before the default route.
I have the following route
routes.MapRoute(
"Segnalazioni_CercaSegnalazioni",
"Segnalazioni/CercaSegnalazioni/{flag}",
new { controller = "Segnalazioni", action = "CercaSegnalazioni", flag = 7 }
);
that maps to the following methon of the class SegnalazioniController:
public ActionResult CercaSegnalazioni(int flag)
{
ViewData["collezioneSegnalazioni"] = Models.Segnalazioni.Recupera(flag);
System.Xml.Linq.XElement x = (System.Xml.Linq.XElement)ViewData["collezioneSegnalazioni"];
return View("Index");
}
How come the link http://localhost:1387/Segnalazioni/CercaSegnalazioni/1 gives me the error
The parameters dictionary contains a null entry for parameter 'flag' of non-nullable type 'System.Int32' for method 'System.Web.Mvc.ActionResult CercaSegnalazioni(Int32)' in 'RecuperoPagatiMvc.Controllers.SegnalazioniController'. To make a parameter optional its type should be either a reference type or a Nullable type.
Nome parametro: parameters
Post all your routes. It sounds like your URL is being handled by a different route than this one. Remember, the order you list your routes does matter. Therefore, if you have another route BEFORE this one that this URL can map to, it will.
MvcContrib contains route debugger. Use it and you'll see which route is called for this url. Here are some instructions how to enable it