I'm getting an error "Unable to retrieve Metadata for "TeamAssignment.Models.Test. Unable to cast object of type "System.Data.Entity.Core.Objects.ObjectContext" to type "System.Data.Objects.ObjectContext."
This is happening whenever I try to create a controller with action/views with the code first entity framework. I'm trying it with a simple test class that's not related to my project and even that is not getting through.
namespace TeamAssignment.Models
{
public class Test
{
[Key]
public int id { get; set; }
public string test { get; set; }
}
public class testDBContext : DbContext
{
public DbSet<Test> testing { get; set; }
}
}
Am I being retarded here or is something wrong with my overall program? I was having some issues with TFS earlier and I'm trying to determine if its related to that.
Sounds like you recently upgraded to EF6.
Unfortunately the MVC 4 scaffolding tools are not compatible with EF6 and there's nothing you can do except upgrade to MVC5 (if possible).
Related
When I try to add Controller using build-in generator I get following error message:
Where "Brand" is a model class and "ApplicationDbContext" is my data context class.
I never encoutered error like this before. It does not occur all the time (2 success vs 30-40 attempts without changing single line of code). I was able to create Controller for same class minutes ago, but it's really annoying when you try to add something new and try more than 10 times with no results.
Of course, I could write my own controller and views, but I really like using included tools.
I have already repaired VS using "Modify" option in "Add or remove". I'm using latest Microsoft Visual Studio Community (MVSC2015 V14.0.25425.01 Update3).
EDIT:
Brand.cs:
namespace AppBrander.Models
{
public class Brand
{
public int ID { get; set; }
public string Email { get; set; }
public string BrandName { get; set; }
public string CompanyName { get; set; }
public string Description { get; set; }
}
}
Works in brand new project, fails in old - I guess it's just my VS installation being totally messed up. I should have been guessed, but I just did second repair...
I have 3 classes inherited from an abstract base class:
abstract class PortTaskStep{
public Guid TaskID { get; set; }
[ForeignKey("TaskID")]
public virtual PortChangeTask PortChangeTask { get; set; }
public virtual String CompleteStep() { return string.Empty;}
}
class PortTaskStep_Add:TaskStep{}
class PortTaskStep_Modify:TaskStep{}
class PortTaskStep_Delete:TaskStep{}
public class HncNetScanContext : DbContext
{
public DbSet<PortTaskStep> PortTaskSteps { get; set; }
}
When I try to get data from table 'PortTaskSteps', the query returns :
cannot calculate the value of the expression
Some more details:
public class PortChangeTask{
public ICollection<PortTaskStep> PortTaskSteps { get; set; }
public Boolean CompleteTask(){
foreach (var portTaskStep in PortTaskSteps)
{
portTaskStep.CompleteStep();
}
}
}
The Domain assembly contains the classes mentioned above are referenced by a web project and a web site. And when I debug the function in the web site, everything goes well.However, when I debug the same function in the web project, the results is null.
The Snapshot
For another scene tested in the Web Project:
As shown in the Snapshot, I try to get "PortTaskSteps". And the result is null. However, after I uncomment the "textQuery", the result is a list of PortTaskStep.
The Snapshot
I think something is going wrong in webconfig or environment of the Web Project, however, I cannot figure out the point...:(
How can I resolve the problem?
Thanks!
Perhaps the right translation might be "Could not evaluate expression". If so, then most likely it's the problem with Visual Studio. Try to delete all your breakpoints from solution and reinsert them. If that doesn't help you, check this link: Visual Studio 2013 'Could not evaluate Expression' Debugger Abnormality.
If the problem for you appears always on both retrieving data and trying to see it in the debug mode then you might want to check your configuration (maybe you've missed mapping or something important for this table).
I am creating a test project in order to learn using asp.net 5 and the mvc 6 framework.
I have decided to create a simple webpage that each menu item comes from the database. To do so I have created a model like such
namespace TestTemplate.Models
{
public class SideMenuItem
{
public int Id { get; set; }
public string Level { get; set; }
public string Label { get; set; }
public string Link { get; set; }
}
}
Inside my Models folder I also have a file named `TestContext.cs'
namespace TestTemplate.Models
{
public class TestContext : DbContext
{
public DbSet<SideMenuItem> SideMenuItems { get; set; }
}
}
That is my EntityFramework DbContext class.
When trying to create a new SideMenu item by using a simple view with a form to adding all the needed data, then using my angular factory that looks like this
return $resource('/api/sidemenu/:id');
I get the error:
An exception of type 'Microsoft.Data.Entity.DbUpdateException' occurred in EntityFramework.Core.dll but was not handled in user code
Additional information: An error occurred while updating the entries. See the inner exception for details.
-->System.Data.SqlClient.SqlException: Invalid object name 'SideMenuItem'.
This error occurs on SideMenuController.cs where I define my API at the part where I am trying to Post the new item:
[HttpPost]
public IActionResult Post([FromBody]SideMenuItem sideMenuItem)
{
if (sideMenuItem.Id == 0)
{
_dbContext.SideMenuItems.Add(sideMenuItem);
_dbContext.SaveChanges(); // ERROR HERE.
return new ObjectResult(sideMenuItem);
}
else
{
var original = _dbContext.SideMenuItems.FirstOrDefault(m => m.Id == sideMenuItem.Id);
original.Level = sideMenuItem.Level;
original.Label = sideMenuItem.Label;
original.Link = sideMenuItem.Link;
_dbContext.SaveChanges();
return new ObjectResult(original);
}
}
I also should mention that before running the app i used
>dnx ef migration add initial
>dnx ef database update
I believe it has to do with me not creating my database correctly. Since I am not seeing any folder on my project that had anything to do with databases or migrations.
Why is it complaining that SideMenuItem is invalid, and how can I fix the issue?
After trying to create my database again, I noticed that I had a typo on my migration command, hence the database was not created.
The command should have been dnx ef migrations ... with an s.
A good starting point with all the commands can be found here.
My application has been built with ASP.NET MVC 4 and Web API. But I have a strange issue to share.
The corresponding code is below
public class MachinesController : ApiController
{
private GWData db = new GWData();
// GET api/Machines/5
public Machine GetMachine(int id)
{
Machine machine = db.Machines.Single(m => m.Id == id);
if (machine == null)
{
throw new HttpResponseException(Request.CreateResponse(HttpStatusCode.NotFound));
}
return machine;
}
Using following URL, I can examine my API Get method of a controller in Web API.
http://localhost/myweb/api/machines/1
And it worked but trying
http://localhost/myweb/api/machines/2
makes Web API hangs forever while memory usage of w3wp.exe keeps going up. So I had to eventually kill the w3wp.exe process. Further by making breakpoint inside of the GET method, I made sure that the hanging happens after getting right data and leaving the method.
How can I approach this kind of issue?
I should've found this cause earlier. This was a problem in serialization of Json. It took forever to serialize navigation properties of an entity if it has many related records. Of course, it was my fault to forget to disable lazy loading. Adding following code solved the problem.
public MachinesController()
{
db.ContextOptions.LazyLoadingEnabled = false;
}
I don't think your solution is correct. Instead you may want to have a model to view model structure, where view model object is flat and exposes only the properties you want to:
class Order
{
// properties you want to expose
public DateTime OrderDate { get; set; }
// navigation and other properties you don't want to expose
public Guid OrderId { get; set; }
public Customer Customer { get; set; }
public ICollection<Address> Addresses { get; set; }
public ICollection<Tax> Taxes { get; set; }
}
class OrderViewModel
{
public DateTime OrderDate { get; set; }
}
The easiest way to create one from another is to use AutoMapper.
I am attempting to seed data for an MVC 4 project using SQL server 4.0 as the database engine, using the Microsoft MVC music store tutorial as an example. I have set up a seed and DB context models, but the controller is not able to find the data. I have verified that the the database file is created in App_Data and verified that SetIntitializer is correctly set up in Application_Start. Here is what I have for code:
Seed data:
namespace RationalMethodApp.Models
{
public class StartData : CreateDatabaseIfNotExists<RationalMethodEntities>
{
protected override void Seed(RationalMethodEntities context)
{
new List<Basin>
{
new Basin {
basinId = 1, // attempting to force a key value, will remove
Name = "Replace me with a real basin",
Location = "In a real location",
drainageArea = 0.0M
}
}.ForEach(b => context.Basins.Add(b));
Controller:
public ActionResult Index(int? bsnId)
{
if (bsnId == null) // here to force a key value, will change
bsnId = 1;
var basin = rmDb.Basins.Find(bsnId);
return View(basin);
}
The context class is:
namespace RationalMethodApp.Models
{
public class RationalMethodEntities : DbContext
{
public DbSet<Basin> Basins { get; set; }
public DbSet<SubArea> SubAreas { get; set; }
public DbSet<IdfCurve> IdfCurves { get; set; }
public DbSet<Analysis> Analyses { get; set; }
public DbSet<FlowSegment> FlowSegments { get; set; }
public DbSet<SheetFlowN> SheetFlowNs { get; set; }
public DbSet<RunoffCoefficient> RunoffCoefficients { get; set; }
public DbSet<StormFrequency> stormFrequencies { get; set; }
}
}
The debugger tells me that the "basin" object is still null in the controller after the .Find. This must be a simple, basic thing that I have overlooked, but all of the help I can find on-line assumes that the askers know what they are doing - not true in my case! I have also checked the discussion at Entity Framework database seed doesn't seed
but this does not seem to be the answer. Please bear with a total noob question.
You don't show the full code of you seed, so i can't really be sure, but you might be missing the Context.Changes().
As well you wrote
public class StartData : CreateDatabaseIfNotExists<RationalMethodEntities>
If you don't delete your database before the application start, it won't do anything as the db already exists.
You could use :
public class StartData : DropCreateDatabaseAlways <RationalMethodEntities>
to drop it every time you start or
public class StartData : DropCreateDatabaseAlways <DropCreateDatabaseIfModelChanges >
to drop db when Model changes (which is great for start of dev)
To debug: Drop your database, kill your application server (so it goes back to application start), breakpoint in your seed. Start Debug, if it goes in seed, check that data is in it after SaveChange().