I have seen a few questions like this, but none seem to answer my question - the most common response seems to be 'Lazy Loading - The database/tables will be created when you try to access them' in this case I am:
Dim students As List(Of Student) = db.Students.ToList
The above is throwing an error, because students table is empty/null.
Here is my (very simple) SchoolContext:
Imports System.Data.Entity
Public Class SchoolContext
Inherits DbContext
Public Students As DbSet(Of Student)
End Class
Here is my SchoolInitialiser class:
Imports System.Data.Entity
Public Class SchoolInitializer
Inherits DropCreateDatabaseAlways(Of SchoolContext)
Protected Overrides Sub Seed(context As SchoolContext)
Dim students As List(Of Student) = New List(Of Student) From {
New Student("Jessica", "Jones"),
New Student("Chuck", "Norris"),
New Student("Rambo", "John")
}
For Each student In students
context.Students.Add(student)
Next
context.SaveChanges()
End Sub
End Class
And my connection string in web.config:
<add name="SchoolContext" connectionString="Data Source= (LocalDb)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\school.mdf;Initial Catalog=aspnet-WebApplication1-20160205092922;Integrated Security=True" providerName="System.Data.SqlClient" />
And finally my global.asax where I am calling the SetInitialize function
Imports System.Data.Entity
Imports System.Web.Optimization
Public Class MvcApplication
Inherits System.Web.HttpApplication
Protected Sub Application_Start()
Database.SetInitializer(New SchoolInitializer)
AreaRegistration.RegisterAllAreas()
FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters)
RouteConfig.RegisterRoutes(RouteTable.Routes)
BundleConfig.RegisterBundles(BundleTable.Bundles)
End Sub
End Class
No database seems to be created within my AppData folder and as far as I can tell, everything is set up okay? Any suggestions?
I am following the following tutorial: https://www.youtube.com/watch?v=VAtVv1Q7ufM
Thanks!
So I figured this one out, in case anybody comes across a similar problem. I was using VB, so I imagine some things got lost in translation from c#.
There were actually a few issues for this. The first one was that the StudentContext class needed properties for the tables, not global variables:
'NOT Public Students As DbSet(Of Student)
Public Property Students() As DbSet(Of Student)
After this, the errors were easier to figure out. The second error was due to not having a key on my Student model, so I added this:
<Key()>
Public Property _StudentID As Integer
To both the property and the global variable. Next, it was not connecting to the database for some reason, so I had to download and install localDB.
Finally, it was complaining that I didn't have a parameterless constructor. So I had to add in an empty constructor in my student model.
FINALLY - everything is working (yay)
Related
I'm trying to simply access information in a existing database using vb.net MVC. The issue is, when i run the code, it creates a table in the database, with a name similar to the table I'm attempting to access with an 's' appended on the end.
e.g:
Existing table: VXPartsData.
Table created after running application: VXPartsDatas
I've managed to do this in c sharp quite easily, but don't understand where I'm going wrong using VB. If someone could please point me in the right direction, thanks
Imports System.Data.Linq
Imports System.Data.Linq.Mapping
Imports System.ComponentModel.DataAnnotations
Imports System.Data.Entity
Namespace Models
<Table(Name:="dbo.VXPartsData")>
Public Class VXPartsData
<Key()>
Public Property PartNo As String
Public Property CustPart As String
Public Property ShortDesc As String
Public Property Part As String
Public Property Price As Decimal
Public Property DiscCode As String
Public Property Kit As Boolean
Public Property VXCODE As String
End Class
Public Class ProductContext
Inherits DbContext
Public Property VXPartsDatas As DbSet(Of VXPartsData)
End Class
End Namespace
Controller:
Imports System.Data.Entity
Imports Videx_PB2.Models
Public Class HomeController
Inherits System.Web.Mvc.Controller
Private db As New ProductContext
Function Index() As ActionResult
Return View(db.VXPartsDatas.ToList())
End Function
End Class
Connection String:
<connectionStrings>
<add name="ProductContext" connectionString="server=(localdb)\MSSQLLocalDB; database=VidexPB; integrated security=SSPI" providerName="System.Data.sqlClient" />
</connectionStrings>
In your ProductContext class, add the following code:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
...
modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
...
base.OnModelCreating(modelBuilder);
}
EF will not pluralize table names
I'm using ASP.NET MVC5 with Identity 2 framework, Database first
I'm trying to custom AspNetRoles, by adding a column called MyCustomColumn
However, my app crashes because :
Invalid Column Name Discriminator
There is a lot of resources on SO and elsewhere on the web, but most of them are with CodeFirst approach and I can't use them in my app.
How to deal with it ?
Actually, none of this is necessary. Most likely you failed to update your context to inherit from IdentityDbContext<TUser, TRole, TKey, TUserLogin, TUserRole, TUserClaim>, rather than the default of IdentityDbContext<TUser>. Since you did not pass your custom role entity as the TRole type parameter, the context instead uses IdentityRole as the class type. It then creates a table for IdentityRole, sees that your custom role inherits from IdentityRole, and therefore adds the Discriminator column so that it can tell the different between an instance of IdentityRole and your custom role, in the database (single table inheritance is the default strategy EF employs).
This will technically work, but your custom role will never actually be utilized. Use the right generic abstract context class, and you'll be fine.
For what it's worth, you should do away with the EDMX stuff, as well. It's deprecated, buggy, and unnecessary. Despite the name, "Code First" can be used with an existing database or to create a new one.
DON'T
public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
DO
public class ApplicationDbContext : IdentityDbContext<ApplicationUser, CustomRole, string, IdentityUserLogin, IdentityUserRole, IdentityUserClaim>
Ok, as I spend some hours to find a solution, I post it here, if it could help someone else.
First, in AspNetRoles, create your custom column AND a column called Discriminator (which is a nvarchar(max) ). Update your .edmx
Then, we have to create a class which inherits from IdentityRole. We will use this class to access our custom column we just created :
In Models folder
public ApplicationRole()
: base() { }
public ApplicationRole(string name, long myCustomValue)
: base(name)
{
MyCustomValue = myCustomValue;
}
public virtual long MyCustomValue { get; set; }
Then, let's create a class which inherits from RoleManager<ApplicationRole>.
I placed it in IdentityConfig.cs, but maybe it's a best practice to place it elsewhere...
For information, I get inspired by this blog, Re-Implementing RoleStore and ApplicationRoleManager paragraph
public class ApplicationRoleManager : RoleManager<ApplicationRole>
{
public ApplicationRoleManager(
IRoleStore<ApplicationRole, string> roleStore)
: base(roleStore)
{
}
public static ApplicationRoleManager Create(
IdentityFactoryOptions<ApplicationRoleManager> options, IOwinContext context)
{
return new ApplicationRoleManager(
new RoleStore<ApplicationRole>(context.Get<ApplicationDbContext>()));
}
}
ApplicationRoleManager has a constructor which calls our previously created ApplicationRole class.
Now we have to register our ApplicationRoleManager at startup, so we have to add this line after the others CreatePerOwinContext
In App_Start\Startup.auth.cs, ConfigureAuth(IAppBuilder app) method
app.CreatePerOwinContext<ApplicationRoleManager>(ApplicationRoleManager.Create);
So now we can use our ApplicationRoleManager, correctly instanciated :
var rm = new ApplicationRoleManager(new RoleStore<ApplicationRole>(new ApplicationDbContext()));
And then use it as we want
var roleName = rm.FindByName("Admin");
string myCustomData = roleName.CustomData.ToString();
i'm trying to build a class library for all of my mvc-5 projects. For that task i started with setting up some Abstract Classes for my DB Context and Indentity User like this
Public MustInherit Class ApplicationUserAbstract
Inherits IdentityUser
End Class
Public MustInherit Class DatabaseContextAbstract
Inherits DbContext
Public Property Users as DBSet(of ApplicationUserAbstract)
Sub New()
MyBase.New()
End Sub
Public Sub New(nameOrConnectionString As String)
MyBase.New(nameOrConnectionString)
End Sub
Protected Overrides Sub OnModelCreating(modelBuilder As DbModelBuilder)
MyBase.OnModelCreating(modelBuilder)
End Sub
End Class
I think i have to get another approach to set DatabaseContextAbstract.Users to the correct Class inherting something like T of ApplicationUserAbstract. Any sugestions for that? I have no clue how to pass this to Users except Using something like
Public MustInherit Class DatabaseContextAbstract(of T as ApplicationUserAbstract)
Inherits DbContext
Public Property Users as DBSet(of T)
End Class
My next question: how would i access the current Instance of DatabaseContextAbstract in my abstract class? All approaches of DatabaseContextAbstract(of DatabaseContextAbstract(... would be nonsense...
EDIT:
The basic idea behind this is to pack Tables and Functions in that abstract Classes. e.g. There are the same UserRight and Group Tables behind every ApplicationUser in all of my projects. But every project may have project specific tables additionally to the base tables. There is still just one Application user in every project.
I don't see a whole lot of point to what you're doing here. IdentityUser is already abstract. It's intended that you're going to create a concrete class that inherits from it. If you perhaps intended to have multiple different types of users that all shared some subset of custom properties, I could see maybe adding an abstract subclass of IdentityUser that implements those, but you're not doing that here. However, even if you did, the user for Identity is a bit of a special case. You can only have one user table, so inheritance must start from a concrete base class, regardless. For example, the following will work fine:
public class ApplicationUser : IdentityUser {}
public class FooUser : ApplicationUser {}
public class BarUser : ApplicationUser
This will not work:
public abstract class ApplicationUserAbstract : IdentityUser {}
public class FooUser : ApplicationUserAbstract {}
public class BarUser : ApplicationUserAbstract {}
In the second scenario, FooUser and BarUser would get separate tables, which is not supported by Identity. In the first scenario, single-table inheritance will be utilized so FooUser and BarUser will be in the same table as ApplicationUser, with a discriminator column.
When it comes to your context, again, there's limited utility in having a base abstract context class. The context is inherently tied to a database, and it doesn't make sense to have multiple context each interacting with its own unique database that are all virtually carbon-copies. Even if you're dealing with a multi-tenant app, you only need one context. The individualization of the databases would be handled via the connection string, not which context class is utilized.
Finally, if you're using Identity, your context should inherit from IdentityDbContext, not DbContext. Among other things IdentityDbContext already contains a DbSet for users, so the one you added is unnecessary.
Long and short, none of this code does anything for an application. It's pointless abstraction for the sake of abstraction.
I am complete beginner with ASP.net and VB.net, I created two classes one for Teams and another for Fixtures which will take in 2 teams.
Imports System.Data.Entity
Public Class Team
Public Property ID() As Integer
Public Property Name() As String
Public Property Points() As Integer
End Class
Public Class TeamDBContext
Inherits DbContext
Public Property Teams() As DbSet(Of Team)
End Class
Imports System.Data.Entity
Public Class Fixture
Public Property ID() As Integer
Public Property Week() As Integer
Public Property HomeTeam() As Team
Public Property AwayTeam() As Team
End Class
Public Class FixtureDBContext
Inherits DbContext
Public Property Fixtures() As DbSet(Of Fixture)
End Class
I created a FixturesController with the read/write actions and views. However when I go to create a Fixture in my application I only see a field for Week and not field for HomeTeam or AwayTeam.
Well you need to add them manually. Brad Wilson wrote a nice article explaining in details how you could make the templated helpers to recursively descend in your nested models.
Also as a side remark you probably don't need 2 db contexts, one should be enough and it could contain both your Teams and Fixtures:
Public Class FixtureDBContext
Inherits DbContext
Public Property Teams() As DbSet(Of Team)
Public Property Fixtures() As DbSet(Of Fixture)
End Class
i'm just starting out with asp.net mvc. It's a long way before you can really get to a live project. At the moment i'm working to build a blog using the asp.net mvc unleashed book.
However, i don't understand the 2 constructors in the BlogController (see question below)
Thx...
FIRST
The BlogController has a private variable '_repository'
Private _repository As BlogRepositoryBase
Public MustInherit Class BlogRepositoryBase
'blog entry methods
Public MustOverride Function ListBlogEntries() As List(Of BlogEntry)
Public MustOverride Sub CreateBlogEntry(ByVal BlogEntryToCreate As BlogEntry)
Public MustOverride Function QueryBlogEntries() As IQueryable(Of BlogEntry)
End Class
The BlogRepositoryBase gets inherited by EntityFrameworkBlogRepository _
The EntityFrameworkBlogRepository connects with BlogDBEntities
NEXT
The controller has 2 constructors 'new' and 'new with a parameter'
Public Sub New()
Me.New(New EntityFrameworkBlogRepository())
End Sub
Public Sub New(ByVal repository As BlogRepositoryBase)
_repository = repository
End Sub
QUESTIONS
What's going on with the constructors, i don't get that
How can a class of type 'EntityFrameworkBlogRepository' be passed to 'sub new' as BlogRepositoryBase? Isn't that another type?
The default constructor is calling the constructor with a parameter with a new instance of a particular type of BlogRepositoryBase class. EntityFrameworkBlogRepository must derive from this base class. The reason that you specify the base class (I would have used an interface, but I digress) is so in your tests you can specify a different type of repository -- one, perhaps, that doesn't even connect to a database by instantiating it directly via the non-default constructor. The framework wiil always use the default constructor, thus you have to both provide it and provide a suitable implementation of the repository using it.
FWIW -- this is how I would do it (in C# -- my brain isn't working well enough to translate into VB, yet).
protected IBlogRepository Repository { get; set; }
public BlogController() : this( null ) {}
public BlogController( IBlogRepository repository )
{
this.Repository = repository ?? new EntityFrameworkBlogRepository();
...
}
Tested as
public void Test()
{
var repository = MockRepository.GenerateMock<IBlogRepository>();
var controller = new BlogController( repository );
...
repository.VerifyAllExpectations();
}
EntityFrameworkBlogRepository is derived from BlogRepositoryBase
The 'magic' in the constructors is called Dependency Injection. (Wiki has more on that here.) In short, it is a way of making your code more maintainable and testable by passing it it's dependencies ... if you change the repository type you need not rip out most of your code.
Kindness,
Dan
Coding custom IControllerFactory or DefaultControllerFactory inherits class. And SetControllerFactory global.asax.
Haaked becomes reference very much.
TDD and Dependency Injection with ASP.NET MVC