I was trying to develop an application and created my own database which then was reflected to an entity model using database first. So I now already have let's say myOwnDBContext.
Then I thaught it wuld be a nice idea to mix it with the classes generated by IdentityDbContext. But when i just changed the connection string in IdentityModel like this
public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
public ApplicationDbContext()
: base("myOwnDBConnectionString")
{
}
}
The tables were not generated as I would expect in myOwnDB but instead I received the following error.
The entity type ApplicationUser is not part of the model for the
current context.
Is there a way I can mix the defualt database of IdentityDbContext with my own databse?
I'm not sure if this can work without using EF migrations, but I do have it working with migrations. Specifically, two DbContext derived classes (one for custom entities, one derived from IdentityDbContext).
For the migrations I had to enable-migrations from the package manager console for both contexts and use the -MigrationsDirectory parameter to place the two sets of migrations into distinct folders (a new feature for EF6).
Then when running update-database the tables are created properly for each context. The update-database command will need a -ConfigurationTypeName parameter to specify the exact migration to use.
Related
I have a entity framework 6 code-first project. I deleted my database and want to re-create it from scratch. When I run update-database some of the migrations do not run. That causes an error later because the database is not in the expected state.
This is the first migration that is skipped:
using System.Data.Entity.Migrations;
public partial class add_ConversationEntry_Type : DbMigration
{
public override void Up()
{
AddColumn("dbo.ConversationEntry", "Type", c => c.String(nullable: false));
}
public override void Down()
{
DropColumn("dbo.ConversationEntry", "Type");
}
}
It looks standard. It inherits from DbMigration and does nothing weird. The next 3 also are skipped and they all affect that dbo.ConversationEntry table.
With update-datebase -verbose it shows 'Applying explicit migrations:' and lists the migrations and these are missing from that list.
I have verified that these are also in the project file.
Where does update-database get the list of migrations?
Why would some be skipped?
The best thing to do in this scenario is to create an idempotent script of all the migrations and see what Entity Framework is trying to do:
update-database –SourceMigration $InitialDatabase -Script
This should have everything needed to create the database, the __MigrationHistory table and to consecutively apply your migrations.
If all other databases you care about are up to date, you could simply reset the migrations. Yet another option would be to switch the initializer to createdatabaseifnotexists which would create a new database based on your model.
Each entity framework migration consists from three files
entity class .cs
and additional code-behind files
metadata file .Designer.cs
database model snapshot .resx
Make sure <timestamp>_dd_ConversationEntry_Type.Designer.cs file is not missing and is included in your project.
easy easy
Make sure the build action is "Compile" and don't forget to mark this answer as "Correct Answer".
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I am trying to develop a small application using ASP.NET MVC 5.
I am using Entity Framework with a code first approach.
To get started, I created my first model and then followed the steps below to create the table in the database
I opened the Package Manager Console
I executed Enable-Migrations
I executed Add-Migration InitilizeModel1Table
Finally, to create the table I executed Database-Update
In step 3 created a migration called datetime_InitilizeModel1Table which created the code that will create the table automatically.
In step 4, it applied the create table command and created the table in the database as expected.
Now, I created 3 more models and what I like to do is create a separate migration for each to keep my code separated.
So I thought I would start again at step 2 and so the following
Add-Migration InitilizeModel2Table
Add-Migration InitilizeModel3Table
Add-Migration InitilizeModel4Table
Database-Update
But the command Add-Migration InitilizeModel2Table is creating an empty migration without the code that is needed to create the tables.
Here is an example of one
namespace App.Migrations
{
using System;
using System.Data.Entity.Migrations;
public partial class InitilizeModel2Table : DbMigration
{
public override void Up()
{
}
public override void Down()
{
}
}
}
How can I create a new migration for each model without having to manually write the migration script to create the tables?
The problem here was that you weren't adding your models to the context, hence EF did not detect the changes.
EF links the state of the model to the migration via the __MigrationHistory table/the migration files themselves. It compares the latest value in __MigrationHistory to the current state of your context, if they are different then a new, non-empty migration will be created when you run Add-Migration X.
Here are a couple of resources describing code-first migrations.
I am by no means an EF expert, so I may be slightly off in the details here.
I'm using EF6 in ASP.NET 5 project. Where I'm using ASP.NET Identity as the authentication mechanism. As anyone would do, I have modeled my domain objects in a separate dll project and for data access logic I have a separate project. This data project contains EF migrations, DbContext for domain models, repositories and Unit of work.
And I have a service layer which is contacted by ASP.NET controllers and this service layer will communicate with data layer and do required operations.
In the main ASP.NET web project I have the default DbContext which is related to Identity and it's migrations.
Having two DbContexts somehow prevents me from updating database automatically. If I had only one DbContext after I create migrations for model changes, it will automatically run on the first time I try to access the website. This doesn't happen anymore, always I have to run the "update-database" command manually.
One solution I have right now is to add a reference to "Microsoft.AspNet.Identity.EntityFramework" in my data project and use Identity context contain my domain tables. But adding an ASP.NET reference in my data project is something I don't want to do unless I have no other options. Because data layer is not even communicating directly with web layer.
Even though this video by Scott Allen discuss about this issue, a solution is not proposed.
You can kick in migrations explicitly by using database initializer and using MigrateDatabaseToLatestVersion. This initializer allows you explicitly state the context and configuration you want to use. Something like:
SetInitializer(new MigrateDatabaseToLatestVersion<MyContext, Configuration>());
You can also call all the logic manually, effectively doing the same as Update-Database cmdlet, when you want during app start. Look at DbMigrator class.
You can run migration inside each DbContext constructor separately.
public class DataContext: DbContext
{
static DaraContext()
{
Database.SetInitializer(new MigrateDatabaseToLatestVersion<DataContext, Configuration>());
}
}
public class ApplicationDbContext : IndetityDbContext
{
static ApplicationDbContext()
{
Database.SetInitializer(new MigrateDatabaseToLatestVersion<ApplicationDbContext, Configuration>());
}
}
I have one issue I am trying to resolve for days now, but I can’t get the right approach.
I am using EF4 and I have one application where I use DataBase First, which originally created the ObjectContext, and I donwloaded the DbContext generator and generated it.
The thing is, I need the application to be able to get the database SCHEMA from some configuration file, instead of ALWAYS using the “dbo” default.
I was trying to use the “ToTable” method (so I can specify the schema) in the “OnModelCreating” overload method but as this article sais, as I am using DataBase First, that method is not called.
How can I make the schema name configurable?
Is that even possible?
I read this article too, where it says I can combine database first with code first but I can’t see how to do that if I can’t use the "OnModelCreating" method.
Thanks a lot in advance!!!
I don't know about configuring schema. However if you want your db first approach to changed to the code first, just change the string parameter of your DbContext constructor.
Suppose that you have the following DbContext that EF Db first created for you:
public class MyDbContext : DbContext
{
public MyDbContext()
: base("Name=DefaultConnection")
{
}
// DbSets ...
}
change that to the following to start using code first and all magic tools of it (migration, etc.):
public class MyDbContext : DbContext
{
public MyDbContext()
: base("YourDbFileName")
{
}
// DbSets ...
}
It causes that EF creates a new connection string using SQL Express on your local machine in your web.config file with the name YourDbFileName, something just like the early DefaultConnection Db first created.
All you may need to continue your way, is that edit the YourDbFileName ConStr according to your server and other options.
I have an ASP.NET MVC 4 project with Entity Framework 5, .NET 4.5 and Visual Studio 2012.
In my solution I've put all the models in a project called Model, all the Repositories and my DbContext in one more project called Data.
I activate the migrations in the Data project with the Enable-Migrations command. I decide to handle them manually. If I create a new migration with the Add-Migration command everything works very well. If, for example, I add a new column to a table, it works fine. I can see the new column in the database schema and I see the new record into the _MigrationHistory table.
At this point, with the new column created, I need to add this column to the right model. So, i add this method to my code-first model class and I run the project.
It delete my database, and init it with the initial migration.
I can't tweak a model without loosing all data.
How I can avoid this behavior?
Thanks
UPDATE:
Configuration.cs
namespace NegoziazioneEventi.Data.Migrations
{
using System;
using System.Data.Entity;
using System.Data.Entity.Migrations;
using System.Linq;
internal sealed class Configuration : DbMigrationsConfiguration<NegoziazioneEventi.Data.NeDataContext>
{
public Configuration()
{
AutomaticMigrationsEnabled = false;
}
protected override void Seed(NegoziazioneEventi.Data.NeDataContext context)
{
}
}
}
Application_Start() in Global.asax
protected void Application_Start()
{
// init basic data on database
System.Data.Entity.Database.SetInitializer(new Models.InitData());
AreaRegistration.RegisterAllAreas();
RegisterGlobalFilters(GlobalFilters.Filters);
RegisterRoutes(RouteTable.Routes);
_container = Bootstrapper.GetWindsorContainer();
}
I decide to handle them manually. If I create a new migration with the Add-Migration command everything works very well.
...
At this point, with the new column created, I need to add this column to the right model. So, i add this method to my code-first model class and I run the project.
That is completely wrong usage of migrations and it is also the reason why EF deletes your database. You must first add property to model and then add migration because EF needs to store correct data into _MigrationHistory table to match that record with the real meaning of that migration.
With your current approach EF runs the application and checks _MigrationHistory table but the record in the table doesn't contain information about your newly added property so EF believes that new change was done to your model and uses default strategy to delete database and create a new one reflecting your current model. You can turn off this behavior but you should start by using migrations correctly!
To turn off the behavior use:
Database.SetInitializer<YourDatabaseContext>(null);
You are using your own initializer which is most probably derived from wrong build-in initializer causing drop of your current database.