Working with EF 6.1. I've created two table class files:
Public Class Student
Public Property StudentID() As Integer
Public Property StudentName() As String
Public Property DateOfBirth() As DateTime
End Class
Public Class Standard
Public Property StandardID() As Integer
Public Property StandardName() As String
End Class
Also created one DbContext file (SchoolContext.vb):
Imports System.Data.Entity
Namespace TestDataAccess
Public Class SchoolContext
Inherits DbContext
Public Sub New()
MyBase.New(ConfigurationManager.ConnectionStrings("dbConnString").ConnectionString)
End Sub
Private _Students As DbSet(Of Student)
Private _Standards As DbSet(Of Standard)
End Class
End Namespace
In my test page, I'm making reference to the DbContext file by using the following:
Dim context As SchoolContext = New SchoolContext
but it keeps giving the error "Type 'SchoolContext' is not defined." Even tried importing the namespace 'TestDataAccess' but still received the error. I did install EF into my project via NuGet, and it show in my packages.config file, so I know that's not the issue.
<package id="EntityFramework" version="6.1.2" targetFramework="net451" />
Any ideas what could be wrong?
I am nog very familiare with vb, but what is the scope of your DbContext.
Shouldn't _standards and _studente be public instead of private?
You need the EntityFramework.dll reference (and not System.Data.Entity).
Related
I've an old programm with edmx. Inside this one, I've linked a class (Table) To a View (Table/filter on a value of a column)
I want migrate this project to code first.
I copy/paste the project delete edmx file and generate models from an existing database.
All is good except this link.
<Table("JoinAffectation")>
partial public Class JointAffectation
public property Id as Long
public IdRecherche as Integer 'the link with my view
<NotMapped>
<ForeignKey("Id")>
PUBLIC OVERRIDABLE PROperty RechercheJoint as ViewRechercheJoint
But When I try to use function of automatical sort/filter using expression
I've error : The specified type member 'RechercheJoint' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported.
If I removed I error saying I don't same comumn and property... Also , How Can I stipulate RechercheJoint is mapped on IdRecherche
thanks for your help
Finally Using modelbuilder, I can join my view and my table like in edmx
<Table("JointAffectation")>
Partial Public Class JointAffectation
Public Property Id As Long
Public Property IdTypeJoint As Long
Public Property IdRecherche As Integer
Public Overridable Property JointType As JointType
<ForeignKey("Id")>
Public Overridable Property RechercheJoint As ViewRechercheJoint
End Class
<Table("ViewRechercheJoint")>
Partial Public Class ViewRechercheJoint
<Key>
<DatabaseGenerated(DatabaseGeneratedOption.None)>
Public Property Id As Integer
<StringLength(50)>
Public Property Libelle As String
<ForeignKey("IdRecherche")>
Public Overridable Property JointAffectations As ICollection(Of JointAffectation)
End Class
modelBuilder.Entity(Of JointAffectation)() _
.HasRequired(Function(e) e.RechercheJoint) _
.WithMany(Function(e) e.JointAffectations) _
.HasForeignKey(Function(e) e.IdRecherche)
I have a DLL file created in VB6. It contains a class named Product and that contains the following simple code:
Option Explicit
Private sDescription As String
Public Property Get Description() As String
Description = sDescription
End Property
Public Property Let Description(Value As String)
sDescription = Value
End Property
I want to use this DLL in VB.NET, which is nothing more than registering the DLL on my system and including the DLL file in the references. Visual Studio automatically generates an interop DLL to consume the COM DLL. This interop DLL generates interfaces for all classes. In VB.NET I want to create a new class that implements the Product interface from the interop DLL. So I code:
Imports myAssembly
Public Class NetProduct
Implements myAssembly.Product
Public Property Description As String Implements _Product.Description
Get
Throw New NotImplementedException()
End Get
Set(value As String)
Throw New NotImplementedException()
End Set
End Property
End Class
The property is auto-generated because I implemented the Product interface. But here comes the problem because when I start using the NetProduct class I get an error telling me this:
Method 'set_Description' in type 'myProject.NetProduct' from
assembly 'myProject, Version=1.0.0.0, Culture=neutral,
PublicKeyToken=null' does not have an implementation.
The problem is that there is no method set_Description in the interface. When I view the definition of the Product interface it shows me the following:
Imports System.Runtime.InteropServices
Namespace myAssembly
<CoClass(GetType(ProductClass))> <Guid("49CE2F98-931C-441B-B322-9F39B6D6F212")>
Public Interface Product
Implements _Product
End Interface
End Namespace
The definition of the _Product interface is:
Imports System.Runtime.InteropServices
Namespace myAssembly
<Guid("49CE2F98-931C-441B-B322-9F39B6D6F212")> <TypeLibTypeAttribute(4304)>
Public Interface _Product <DispId(1745027072)>
Property Description As String
End Interface
End Namespace
When I use the interface myAssembly.Product directly to create a new object then everything works as you would expect. The property does not pose a problem there. But when I implement the interface in a .NET class the problem arises.
How do I solve this?
[update 1] After creating a method Set_Description I see the following error appear:
property 'Description' implicitly defines 'set_Description', which
conflicts with a member of the same name in class 'NetProduct'.
This must have something to do with my problem, although I don't know what it is. I already tried completing the property to make sure the Throw New NotImplementedException() wouldn't be in the way but that didn't make the error go away. My code builds just fine by the way. The error I gave earlier is a runtime error. Not a build error.
Private myDescription As String
Public Property Description As String Implements Product.Description
Get
Return myDescription
End Get
Set(value As String)
myDescription = value
End Set
End Property
[update 2] I have used JetBrains DotPeek to disassemble the interop.dll that Visual Studio generates. Disassembly is coded in C#. It contains 2 interfaces and 1 class for the single Product class from VB6. Here are all details.
I'll start with the Product class itself.
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
namespace myAssembly
{
[ClassInterface(0)]
[Guid("C54B96A8-1499-4B76-8508-0B732E551326")]
[TypeLibType(2)]
[ComImport]
public class ProductClass : _Product, Product
{
[MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
public extern ProductClass();
[DispId(1745027072)]
public virtual extern string Description { [DispId(1745027072), MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)] [return: MarshalAs(UnmanagedType.BStr)] get; [DispId(1745027072), MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)] [param: MarshalAs(UnmanagedType.BStr), In, Out] set; }
}
}
The ProductClass uses 2 interfaces. I don't understand why because one of those is just an implementation of the other. This is the Product interface.
using System.Runtime.InteropServices;
namespace myAssembly
{
[CoClass(typeof (ProductClass))]
[Guid("49CE2F98-931C-441B-B322-9F39B6D6F212")]
[ComImport]
public interface Product : _Product
{
}
}
And then we have the _Product interface. They even share the same Guid. It might have something to do with backwards compatibility.
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
namespace myAssembly
{
[Guid("49CE2F98-931C-441B-B322-9F39B6D6F212")]
[TypeLibType(4304)]
[ComImport]
public interface _Product
{
[DispId(1745027072)]
string Description { [DispId(1745027072), MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)] [return: MarshalAs(UnmanagedType.BStr)] get; [DispId(1745027072), MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)] [param: MarshalAs(UnmanagedType.BStr), In, Out] set; }
}
}
This is all I could find. Still no clue where the error for Set_Description comes from.
[Update 3] Example code
The code for the VB6 class is on top of this question. Nothing fancy there. The code for testing implementation in .NET is like this:
Imports myAssembly
Public Class NetProduct
Implements myAssembly.Product
Private myDescription As String
Public Property Description As String Implements Product.Description
Get
Return myDescription
End Get
Set(value As String)
myDescription = value
End Set
End Property
End Class
To test the NetProduct class I dropped a Button on a Form and create an instance of the class when the button is being clicked.
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click '<- Error happens here, so on loading the datatype!
Dim Product As New NetProduct 'Error does NOT happen here.
End Sub
The whole project compiles without errors. The project even runs without errors UNTIL you click the button. Probably because the NetProduct type is first loaded on that point.
I used a console app to do my test. Other than that, my VB.NET code is basically identical to yours in update 3. The VB.NET properties were auto-generated by VS with the stub Throw New NotImplementedException() after using the Implements statement :
Imports OurCOMDll
Class TestClass
Implements OurCOMDll.ClassInCOMDll
Dim msStringProperty As String = String.Empty
Public Property StringProperty As String Implements _ClassInCOMDll.StringProperty
Get
StringProperty= msStringProperty
End Get
Set(value As String)
msStringProperty = value
End Set
End Property
End Class
Module Module1
Sub Main()
Dim o As New OurCOMDll.ClassInCOMDll
o.StringProperty = "Hello World!"
Console.WriteLine(o.StringProperty) ' Outputs 'Hello World!' as expected
Console.ReadLine()
End Sub
End Module
Same is true for the VB6 code. The string property is implemented like yours.
Distinguishing factors so far:
VS 2019 vs. VS 2017
(Consuming) GUI vs. Console application
Different property names
I'm toying around with a 3rd party library and something has me absolutely puzzled.
When I instantiate this class, immediately all of the properties of the class throw exceptions before any more code even runs. Why is this happening? It's not just this TypedSegmentPWK class, it's all of the typedsegment classes.. of which there are many.
Simple instantiation fails
Imports OopFactory.X12.Parsing
Imports OopFactory.X12.Parsing.Model
Imports OopFactory.X12.Parsing.Model.Typed
....
Dim test As New TypedSegmentPWK
test.PWK04_EntityIdentifierCode = "blah"
Assigning a value to PWK04_EntityIdentifierCode or any other property of test fails with a null reference exception.
TypedSegmentPWK:
Namespace OopFactory.X12.Parsing.Model.Typed
Public Class TypedSegmentPWK
Inherits TypedSegment
Public Sub New()
Public Property PWK01_ReportTypeCode As String
Public Property PWK02_ReportTransmissionCode As String
Public Property PWK03_ReportCopiesNeeded As Integer?
Public Property PWK04_EntityIdentiferCodeEnum As EntityIdentifierCode
Public Property PWK04_EntityIdentifierCode As String
Public Property PWK05_IdentificationCodeQualifier As String
Public Property PWK05_IdentificationCodeQualifierEnum As IdentificationCodeQualifier
Public Property PWK06_IdentificationCode As String
Public Property PWK07_Description As String
Public Property PWK08_ActionsIndicated As String
Public Property PWK09_RequestCategoryCode As String
End Class
End Namespace
TypedSegment:
Namespace OopFactory.X12.Parsing.Model
Public MustInherit Class TypedSegment
Protected Sub New(segmentId As String)
Public Event Initialized As EventHandler
Public Event Initializing As EventHandler
Protected Overridable Sub OnInitialized(e As EventArgs)
Protected Overridable Sub OnInitializing(e As EventArgs)
End Class
End Namespace
Full source here: https://github.com/KeyMarkInc/OopFactory.X12
All the properties reference _segment defined in TypedSegment, e.g.
public string PWK04_EntityIdentifierCode
{
get { return _segment.GetElement(4); }
set { _segment.SetElement(4, value); }
}
However, the _segment variable is not initialized until TypedSegment.Initialize(Container parent, X12DelimiterSet delimiters) is called...
internal void Initialize(Container parent, X12DelimiterSet delimiters)
{
OnInitializing(new EventArgs());
_segment = new Segment(parent, delimiters, _segmentId);
OnInitialized(new EventArgs());
}
This is an internal method, so presumably something in this framework is supposed to call it, and not you as the user. So, I would guess the answer is that you are using the TypedSegmentPWK class incorrectly, although I don't know what the correct way is.
I have been struggling with the new ASP.NET Identity trying to extend it to do my next web application, I have opend a new empty web project in Visual Studio 2013 Profissional, and added MVC 5 assembly as usual.
I have write the following in VB.NET (Code-First)
Imports System.ComponentModel.DataAnnotations
Imports System.ComponentModel.DataAnnotations.Schema
Imports Microsoft.AspNet.Identity.EntityFramework
Imports System.Data.Entity
Partial Public Class MyAppContext
Inherits IdentityDbContext(Of User)
Public Sub New()
MyBase.New("ConnStr")
End Sub
Public Overridable Property Items As DbSet(Of Item)
End Class
Partial Public Class User
Inherits IdentityUser
<Required>
Public Property Name As String
Public Property Items As ICollection(Of Item) = New HashSet(Of Item)
End Class
Partial Public Class Item
<Key> <DatabaseGenerated(DatabaseGeneratedOption.Identity)>
Public Property ID As Integer
<Required>
Public Property Name As String
<Required>
Public Property UserID As String
<ForeignKey("UserID")>
Public Overridable Property User As User
End Class
I think the code is very straight-forward, i am trying to create "User" class that inherit from "IdentityUser" and adding a one-to-many relationship with another class called "Item", and of course I have to extend the generic class "IdentityDbContext(Of User)".
Then I want to add a controller with the views for my "User" and "Item" classes using the scaffolding option "MVC 5 Controller with views, using Entity Framework".
Error There was an error running the selected code generator: 'Value cannot be null. Parameter name: codeType'
I want you to know that this is a clean setup for visual studio 2013, a clean project, and also the scaffolding works very good for the current model without the Identity inheritance thing.
Please let me know if you have successfully reproduce the problem on your machines.
I wanted to let you know that after i have converted the exact code to C# it worked!...
It seems that this is a vb.net related problem (something with the built-in t4 templetes).
So this is a bug, and i will assume this is the answer.
If somebody found a workaround for this, please post and I will accept it as the answer.
In my project I have it set up so that all the tables in the DB has the property "id" and then I have the entity objects inherit from the EntityBase class using a repository pattern. I then set the inheritance modifier for "id" property in the dbml file o/r designer to "overrides"
Public MustInherit Class EntityBase
MustOverride Property id() As Integer
End Class
Public MustInherit Class RepositoryBase(Of T As EntityBase)
Protected _Db As New DataClasses1DataContext
Public Function GetById(ByVal Id As Integer) As T
Return (From a In _Db.GetTable(Of T)() Where a.id = Id).SingleOrDefault
End Function
End Class
Partial Public Class Entity1
Inherits EntityBase
End Class
Public Class TestRepository
Inherits RepositoryBase(Of Entity1)
End Class
the line
Return (From a In _Db.GetTable(Of T)() Where a.id = Id).SingleOrDefault
however produces the error "Class member EntityBase.id is unmapped" when i use VS 2010 using the 4.0 framework but I never received that error with the old one. Any help would be greatly appreciated. Thanks in advance.
Finally found the answer to my problem.... had to change where a.id = id to a.id.equals(id)