ASP.NET MVC3&4 Code First is not creating tables

Question

Hi all,

I'm really having a breakdown on this Code First approach. I checked everything 10 times, restarted my project 10 times and it's really getting demotivational...

I created 2 classes with for each a context:

Imports System.Data.Entity
Imports System.ComponentModel.DataAnnotations

Public Class B
    <Key()> _
    Public Property ID() As Integer

    <Required(ErrorMessage:="In of uit is vereist")>
    <Display(Name:="In / uit")>
    Public Property InOrOut() As String

    <Required(ErrorMessage:="Hoeveelheid is vereist"), Range(1, 1000000, ErrorMessage:="€ moet groter dan 1 zijn")>
    <Display(Name:="Hoeveelheid")>
    Public Property Quantity() As Integer

    <Range(1, 1000000, ErrorMessage:="ID moet groter dan 1 zijn")>
    <Display(Name:="Bijhorend M-ID")>
    Public Property FromID() As Decimal

    <Display(Name:="Van")>
    Public Property FromWho() As String

    <Required(ErrorMessage:="Datum is vereist")>
    <DataType(DataType.Date)>
    <Display(Name:="Datum")>
    Public Property DateOfAction() As Date

    <Display(Name:="Notitie")>
    Public Property Note() As String

    <Display(Name:="Log-ID")>
    Public Property LogID() As String
End Class

Public Class BDBContext
    Inherits DbContext
    Public Property Bs() As DbSet(Of B)
End Class

Imports System.Data.Entity
Imports System.ComponentModel.DataAnnotations

Public Class Log
    <Key()> _
    Public Property ID() As Integer

    Public Property Account() As String

    Public Property BOrMOrWOrLogOrAccount() As String

    Public Property Action() As String

    Public Property ActionID() As Integer

    Public Property Note() As String
End Class

Public Class LogDBContext
    Inherits DbContext
    Public Property Logs() As DbSet(Of Log)
End Class

I made Initializers:

    Public Class BInitializer
        Inherits DropCreateDatabaseIfModelChanges(Of BDBContext)
        Protected Overrides Sub Seed(context As BDBContext)
            MyBase.Seed(context)
            Dim Bs = New List(Of B) From {
                New B With {.ID = "1", .InOrOut = "In", .Quantity = "1", .FromID = "1", .FromWho = "Eén", .DateOfAction = Date.Parse("1111-11-11"), .Note = "Eén 1", .LogID = "1"},
                New B With {.ID = "2", .InOrOut = "Out", .Quantity = "2", .FromID = "2", .FromWho = "Twee", .DateOfAction = Date.Parse("2222-22-22"), .Note = "Twee 2", .LogID = "2"},
                New B With {.ID = "3", .InOrOut = "In", .Quantity = "3", .FromID = "3", .FromWho = "Drie", .DateOfAction = Date.Parse("3333-33-33"), .Note = "Drie 3", .LogID = "3"},
                New B With {.ID = "4", .InOrOut = "Out", .Quantity = "4", .FromID = "4", .FromWho = "Vier", .DateOfAction = Date.Parse("4444-44-44"), .Note = "Vier 4", .LogID = "4"},
                New B With {.ID = "5", .InOrOut = "In", .Quantity = "5", .FromID = "5", .FromWho = "Vijf", .DateOfAction = Date.Parse("5555-55-55"), .Note = "Vijf 5", .LogID = "5"}}

        End Sub
    End Class

    Public Class LogInitializer
        Inherits DropCreateDatabaseIfModelChanges(Of LogDBContext)
        Protected Overrides Sub Seed(context As LogDBContext)
            MyBase.Seed(context)
            Dim Logs = New List(Of Log) From {
                New Log With {.ID = "1", .Account = "Eén 1", .BOrMOrWOrLogOrAccount = "B", .Action = "Add 1 en 1", .ActionID = "1", .Note = "1x1"}}
            context.SaveChanges()
        End Sub
    End Class

I made my connection strings in web.config:

    <add name="BDBContext"
     connectionString="Data Source=|DataDirectory|Database.sdf"
     providerName="System.Data.SqlServerCe.4.0"/>
    <add name="LogDBContext"
     connectionString="Data Source=|DataDirectory|Database.sdf"
     providerName="System.Data.SqlServerCe.4.0"/>

 I added the initializers to my application start:

        System.Data.Entity.Database.SetInitializer(Of BDBContext)(New Diel.Models.BInitializer())
        System.Data.Entity.Database.SetInitializer(Of LogDBContext)(New Diel.Models.LogInitializer())

What happens:

The database only gets created when i manually create an item from within my application. For some reason, it never runs my initializers...

Are there maybe any more conventions I'm missing?
Can you only use one Context in your project?
Can you use only one connection string?

Thanks for reading this and looking into the code. Thanks for any help at all.

Answer 1

Just found out something weird.

When I start the application to my homepage, it doesn't create anything on my application start.

When I go to B/Index and I check my database, it creates a table named B. When I then go to Log/Index, the application creates the table Log but suddenly my table B is gone.

I'm probably doing something wrong with those 2 Initializers as it seems that they recreate my whole database when they try to initialize one context.

Answer 2

Hi,

It seems expected. First the initializer is triggered when you actually attempt to use the context (at least read or write an entity). So if your homepage doesn't actually do something with a context, no database is created.

Then when you go on a page that display a table, it creates the db.

But then when you go on the other page using another context, it sees the schema changed (as the table you are trying to use is not part of the other context) and it delete/recreate the db according to the current context (that doesn't include the other table that is then lost).

For a start, I would suggest to create a single context with both tables (a context is supposed to represent a single database, not a single table)...

To clarify you are not forced to use a single context though it's likely the standard practice unless you have much more than two tables. If you want a single context for each table, an approach could be an initialization only context with all entities (and make sure to trigger the initialization before uisng the other context).

For now I would recommend to use a single context until you find a real need to switch to a multi context application.

---

Please always mark whatever response solved your issue so that the thread is properly marked as "Answered".

Answer 3

Thanks! Going to try that right away.

I didn't know it was one context per table normally.

Answer 4

Either my clarification attempt is an epic fail or you really meant "I didn't know it was one context per DATABASE normally." ;-)

---

Please always mark whatever response solved your issue so that the thread is properly marked as "Answered".

Answer 5

Hi Patrice,

I'm sad to say, I really meant it. Everything is working now as it should and my adventure to MVC exploration continues. Only weird thing now is that my seeding doesn't work. I'll have a look at that today.

Thanks all!

Answer 6

Doesn't matter. The good point is that you understand now that you should have a single context for all your tables (at least to start with).

For the seed part, you just create a list that isn't related in any way to your context. So the context doesn't know anything about this list and its object instances. What you have perhaps seen is something like http://weblogs.asp.net/scottgu/archive/2010/07/16/code-first-development-with-entity-framework-4.aspx but note that once the unrelated list is created the code calls :

dinners.ForEach(d=>context.Dinners.Add(d));

so that each object found in the private dinners list can be known by the context (that will then be able to save them).

---

Please always mark whatever response solved your issue so that the thread is properly marked as "Answered".