I've got a full .NET Framework 4.6.2 Web API app that I've installed Entity Framework Core 1.1.2 into. It contains some classes, a DbContext class and has the relevant EF Core NuGet packages installed.
When I run Add-Migration Initial in the package manager console within Visual Studio, it correctly identifies the DbContext in the project and produces the migration class as well as a snapshot. The migration looks correct, given that within the Up method, it shows a number of create tables for each of the classes I want, it shows the expected columns for each and the constraints I'd expect, so that looks good. Also, within the Down method, it drops all the tables (which makes sense since this is the first migration done). This migration class is created in the /Migrations directory within the project.
When I run Script-Migration in the console next, it produces a SQL script that is incorrect, in that it only creates the table for the EFMigrationsHistory, as follows:
IF OBJECT_ID(N'__EFMigrationsHistory') IS NULL
BEGIN
CREATE TABLE [__EFMigrationsHistory] (
[MigrationId] nvarchar(150) NOT NULL,
[ProductVersion] nvarchar(32) NOT NULL,
CONSTRAINT [PK___EFMigrationsHistory] PRIMARY KEY ([MigrationId])
);
END;
GO
This SQL file is created in the bin/Debug directory for the project.
I would expect that the output of this Script-Migrations command contain the SQL version of the Up method in the migration class that was produced by the previous Add-Migrations Initial command, but alas, this is not the case. If I run Update-Database, it runs against this SQL file and continues to ignore the existing Migrations.
Similarly, this appears to be a larger issue with EF Core, because if I attempt to do a Remove-Migration as suggested in the console after running Add-Migration, it is also unable to find the Migration it just produced and gives me the following error:
No ModelSnapshot was found.
And I know this can't be the case because I see it right there in the Migrations folder along with the initial migration class it created.
What's going on and is there any known workaround to get these tools working appropriately?
Update
While testing, I've found that if I create a new solution with just these few parts in it, it works fine. However, in my original solution, I have these projects within a number of solution folders, so perhaps that's the issue at hand, because putting the new project in a solution folder causes the same issues observed in the rest of this question.
Related
Locally my database works fine. I try to put a server database to the same version as my development version.
In Visual Studio, I ran this command:
dotnet ef migration scripts lasknown_script_that_was_executed_on_prod_server
where I use the value of
lasknown_script_that_was_executed_on_prod_server
as found on the production server by querying:
SELECT TOP 1000
[MigrationId], [ProductVersion]
FROM
[MyProject].[dbo].[__EFMigrationsHistory]
and yes it's in my source code as well, so seems OK, my code knows that version.
After I perform that command, it creates a large output but on top of that it shows an error
Build started...
Build succeeded.
Error writing app settings | Cannot perform runtime binding on a null reference
info: Microsoft.EntityFrameworkCore.Infrastructure[10403]
Entity Framework Core 6.0.5 initialized 'ApplicationDbContext' using provider 'Microsoft.EntityFrameworkCore.SqlServer:6.0.5' with options: > None
BEGIN TRANSACTION;
GO
CREATE TABLE [MyApplication] ( ...my firs db create..?? ...
I assume therefore the output code is missing something that should go before the very first initial database creation.
(as my prod server is not at that version, it shouldn't start with the first migration).
Locally it works fine, however, and it was set up with code-first.
So it was generated by code, it should migrate as well by code.
I'm using EF 6 and when I run Update-Database it is trying to apply every migration since the beginning of the project, even though there is only migration that is new.
If I attempt to create an empty migration, I get an error that says I can't create a new migration because there are explicit migrations pending.
The only blog post I found with a similar issue suggested dropping the __MigrationHistory table and doing Update-Database -Script, stripping out all the actual DB changes but leaving in the Create __MigrationHistory and Migration Inserts. I didn't drop the table, but I did rename it, and this didn't solve the problem for me.
This question looks like a duplicate, but when I run the script I see that my context key has not changed, so that's not my problem.
What's weird is I added a column to my model, and then did an add-migration with no problem. Then I went to lunch (but without doing an update-database), then after lunch I decided to add another column to my model and when I did add-migration -force again this error started. I've completely rolled back my workspace (completely delete the workspace and removed all code from my machine), but the problem persists.
I am in a team environment, but we each use our own dev databases, and I've verified the connection string is correct in my Migrations App.Config file.
I ran SQL Profiler during the Update-Database -Script command, and it ran the following query 24 times before giving up (12 batches of 2) :
IF db_id(N'ISEPDBContexts.AdministratorDb') IS NOT NULL SELECT 1 ELSE SELECT Count(*) FROM sys.databases WHERE [name]=N'ISEPDBContexts.AdministratorDb'
Which is weird because that's the name of my connection string, not the name of the database.
Turns out the problem was that Package Manager Console wasn't looking at my config file, so a quick search and I found that you have to not only set the Default Project in PMC (which I was doing), but the solution has to have the same project selected as Startup Project. (Credit)
I am currently playing with beta4 of EF7 using the blank ASP.NET web project template.
After having kicked off the existing migration, resulting in the tables being created in the localdb, the following occurs:
Strangely, when I clean up the migration-folder, including removing ApplicationDbContextModelSnapshot.cs and I run
dnx . ef migration add twice, I get the following error:
dnx : System.InvalidOperationException: No data stores are configured. Configure a data store by overriding OnConfiguring in your DbContext class or in the AddDbContext method when setting up services.
The second migration is not created. When I review the created migration it contains all tables whereas the database is already provisioned, so you should expect the migration being empty.
Then, when I remove the first migration and run the add migration command again more than once, all the migrations are correctly created, i.e. as empty files.
Can someone explain this to me? Is this expected behavior or is this a bug in beta4?
Tip for people coming from former EF-versions:
* Don't use the K command framework anymore.
* Don't use the Add-Migration cmdlets anymore.
Both have been replaced by dnx . (dot). (dnx = .NET execution environment)
Some references:
https://github.com/aspnet/EntityFramework/wiki/Entity-Framework-Design-Meeting-Notes---September-11,-2014
http://jameschambers.com/2015/05/project-k-dnvm-dnx-dnu-and-entity-framework-7-for-bonus-points/
Remove the constructor of ApplicationContext. It is a temporary workaround to enable deployment, but it interferes with the Migrations commands.
I'm trying to get Entity framework migrations working. I've enabled code first migrations, its created a migrations folder, config file and the mig history table, but no initial create. Am i missing a step? This is a new db created by EF (4.3.1).
This behavior is not in place by default, but it is available to you easily in many different forms.
You can call context.Database.CreateIfNotExists(); at application startup.
You can use one of the built-in DatabaseInitializers. The CreateDatabaseIfNotExists initializer is built into EntityFramework and just needs to be added to your project.
You could create your own custom database initializer which includes option #1 inside of itself. Example: Code First Migrations and initialization
You can include DatabaseInitializers in your project either by code or via a config file.
Include an EntityFramework Database Initializer via code:
In your application startup you can setup the DatabaseInitializer like so:
System.Data.Entity.Database.SetInitializer<DairyMmmContext>(new System.Data.Entity.CreateDatabaseIfNotExists<DairyMmmContext>());
NOTE: this code has changed multiple times throughout the life of entityframework! This example is for EF 4.3 which is the current production release available via nuget.
Include an EntityFramework Database Initializer via configuration element:
<configuration>
<entityFramework>
<contexts>
<context type="MyNamespace.MyEFDataContext, AssemblyName">
<databaseInitializer
type="System.Data.Entity.CreateDatabaseIfNotExists`2[[MyNamespace.MyEFDataContext, AssemblyName],
[MyNamespace.Migrations.Configuration, AssemblyName]], EntityFramework" />
</context>
</contexts>
</entityFramework>
</configuration>
You'll notice this can be a little "ungraceful" with this configuration. You need to replace AssemblyName above with the name of the assembly you keep your entityframework stuff in, replace MyNamespace.MyEFDataContext with the fully qualified name of your entityframework data context, and replace MyNamespace.Migrations.Configuration with the fully qualified name to your configuration class (by default in the Migration folder inside your project).
EDIT: Edited to respond to additional comments
A migration is a change from one schema definition to another schema definition. Creating the empty database is not a migration (but everything after that is). There will be no migration source file in your project for just creating an empty db, that is done in code by the initializer.
If you are already using the DropCreateDatabaseAlways initializer it should be doing that. However, I noticed you are setting the initializer in code which means there is the opportunity for a timing problem (setting the initializer after your context is already past the point of calling any initializers).
You can force entityframework to run your initializer at any point in code with context.Database.Initialize(true); (The parameter is a true/false to force the initialization regardless of the current state). That would drop and recreate your database every time.
But you can also just make sure your initializer is setup as early as possible in your application's life cycle (before you have created a single instance of your context).
"Initial Create" is NOT created automatically! You need to create that yourself. Some tutorials of EF are confusing and I had the same misunderstanding as you.
What you need to do:
-Add-Migration InitialModel
If you already have created your database tables and domain model, then:
-Add-Migration InitialModel -IgnoreChanges
From this point, your code will be in sync with database. Anytime you change the code, you can use Add-Migration to add the changes to your database.
The article / tutorial here here (on microsoft.com)
describes the reason that an initialCreate migration doesn't exist. The migration will only be added if the Database already exists. Otherwise, the first migration will be the 'initialCreate' as there is no point in creating a migration to a Database that doesn't exist yet... no DB means there is nothing to roll back to, on a down migration.
Here is the pertinent paragraph:
Run the Enable-Migrations command in Package Manager Console
This command has added a Migrations folder to our project, this new folder contains two files:
The Configuration class. This class allows you to configure how Migrations behaves for your context. For this walkthrough we will just use the default configuration.
Because there is just a single Code First context in your project, Enable-Migrations has automatically filled in the context type this configuration applies to.
An InitialCreate migration. This migration was generated because we already had Code First create a database for us, before we enabled migrations. The code in this scaffolded migration represents the objects that have already been created in the database. In our case that is the Blog table with a BlogId and Name columns. The filename includes a timestamp to help with ordering.
If the database had not already been created this InitialCreate migration would not have been added to the project. Instead, the first time we call Add-Migration the code to create these tables would be scaffolded to a new migration.
Not sure it's the same but I had a similar issue. I think my problem was related to the fact that I dont use a connections string from the config file to get my connection string.
Fiddling with the start up project in the solution and also the projet combo in the Package Manager Console I was able to generate that first migration.
Also make shure you have a connections string with the name of your dbContext class so the Package Manager can find it.
I am using EF 6 RC1 and ran into this problem where neither the InitialCreate nor __MigrationHistory were being created when running Enable-Migrations.
Actually, just after upgrading from EF 5 to EF 6 I ran Enable-Migrations and for some reason it created a __MigrationHistory table using the EF 5 schema, so I deleted it and my Migrations directory and tried to start over.
But every time I deleted the Migrations directory it wouldn't create an InitialCreate or __MigrationHistory. I tried dropping and recreating the database and restarting Visual Studio 2012 to no avail. I gave up for the day and the next morning tried again - after letting my computer sit for about 8 hours it then created the InitialCreate. I am guessing there must be a cache somewhere that has a really long timeout - anyone? I am also guessing that rebooting might clear the cache, but I didn't try that.
Whatever the case, it is possible to use PM> Add-Migration InitialCreate to do that step manually.
Anyway, I still didn't get a __MigrationHistory table. Apparently, EF 6 has changed from creating it during the Enable-Migrations command to instead only creating it during the Update-Database command. And since my schema had already been created at that point, I needed to tear it down and recreate it manually:
PM> Update-Database -TargetMigration:0
PM> Update-Database
I also stopped after the first command to check the state of the database to ensure I was updating the correct one, since according to this, the database connection string is picked up or autogenerated depending on the configuration, and unless it is configured right, there is no guarantee you are going to access the database or instance of SQL Server you intend to.
After running both commands it created a __MigrationHistory table - and it didn't create it as a system table (which I didn't really want anyway), so all is good. Not exactly the same problem as the OP, but hopefully this will be helpful to someone else.
References:
http://elegantcode.com/2012/04/12/entity-framework-migrations-tips/
Reset Entity-Framework Migrations
How to recreate migrations from scratch
I know this is old, but there is no accepted answer and I had same issue.
The trick is Enable-Migrations command. As stated here there is a command Enable-Migrations –EnableAutomaticMigrations. What it does it starts migrations exactly where you are.
If you want the first migration to be creation of database, just run Enable-Migrations (without --EnableAutomaticMigrations).
And remember to set initializer:
Database.SetInitializer(new MigrateDatabaseToLatestVersion<LicenseContext, Configuration>());
It looks like CodeFirst stops doing its homework when it doesn't have full control of the database (I suppose).
The scenario is a web site hosted on Arvixe.com (or I suppose any other shared hosting server), where I have to create databases only from their control panel (and NOT with Sql Server Management Studio, just to say...).
Once created an empty database, I register a connection in the web site, and I use it to generate database from poco objects like in:
add-migration m1 -targetdatabase myconnection
This generates correctly my FIRST migration, that I can apply without problems with
update-database -targetdatabase myconnection
The first concern, not too important, is that since the database is existing, it will NOT issue the Seed command, so I have to insert my first records by hand, but this is not a great problem.
Then I change my poco objects, and I need to update the database, but when I issue ANOTHER
add-migration m2 -targetdatabase myconnection
it gives the error:
System.Data.Entity.Migrations.MigrationsPendingException: Unable to generate an explicit migration because the following explicit migrations are pending: [201111081426466_m1]. Apply the pending explicit migrations before attempting to generate a new explicit migration.
This is really strange, since if I look at the database, I can see even the table __MigrationHistory, but then it looks like it cannot recognize it...
Anyone with the same problem, or some good tip to where investigate?
Thanks in advance,
Andrea Bioli
I had this problem. I was able to resolve it by providing a connectionString and a connectionProviderName parameter to both the Update-Database and the Add-Migration commands.
If you have many projects in your solution with multiple config files, Package Manager seems to be confused. In my case, I had one project selected as the default project for Package Manager Console, but it was pulling the connection string from the Visual Studio solution default start-up project instead.