CODEWITHSUNDEEP
entity-frameworkcode-firstentity-framework-migrations
Alfonso Muñoz
Alfonso Muñoz

Reputation: 1639

Code First Migrations for a custom NuGet package can't be executed from main application

I have created a module to be included in a main MVC3 web application. The module is packaged into a NuGet package and it can be installed and uninstalled via NuGet. Both, the main site and the module use Code First, EF >= 4.3

To create the package I have another MVC3 site and all the functionality is inside an area, so to create the package I just pack the libraries, the views and all the needed files. Database Migrations work fine in the project and the package is created nicely.

Now I install the package in the main site via NuGet. This site is in another solution, and the solution has two projects:

The package is installed correctly and the Area, the Area views and libraries are correctly installed.

The problem now is how I update the database? I've tried first to run "Update-Database" but I get the message:

"No migrations configuration type was found in the assembly 'MyProject.Web.UI'. (In Visual Studio you can use the Enable-Migrations command from Package Manager Console to add a migrations configuration)."

I've tried then to enable the migrations with "Enable-Migrations" but I got this other message:

"No context type was found in the assembly 'MyProject.Web.UI'."

I tried also just to run the site and see if the changes are automatically applied but I get the exception page with the typical message:

"The model backing the 'NugetPackageDbContext' context has changed since the database was created. Consider using Code First Migrations to update the database"

I don't know what to do to update the database with the required changes in migrations that come in the NuGet package. Any one could put some light here in this matter? I'm quite new to Migrations, maybe there are some configs to update the database if there is a change instead of running the commands in the console, I'm a bit lost.

Thanks in advance :)

Upvotes: 7

Views: 7094

Answers (4)

Robba
Robba

Reputation: 8314

I realize that this question is very old, but since I don't see this answer I'll throw it in anyway.

To perform migrations and such on projects or external references you can still use the same three command:

Enable-Migrations
Add-Migration
Update-Database

but you wil need to supply some additional parameters. For the Enable-Migrations command you will need to add the -ContextTypeName and optionally the -ContextAssemblyName commands like so:

Enable-Migrations -ContextTypeName MyProject.EntityFramework.NugetPackageDbContext -ContextAssemblyName MyProject

This will give you a migration configuration class in your current project. The other two commands will require you to specify this configuration class:

Update-Database -ConfigurationTypeName MyProject.Web.UI.Migrations.Configuration

Hope that helps

Upvotes: 0

Alfonso Muñoz
Alfonso Muñoz

Reputation: 1639

Good news! It seems that I got it. I was looking for a way to make the NuGet package to update the database to the latest version.

Well, this package comes with an Admin controller, so I added a new action called Update:

public ActionResult Update()
    {
        System.Data.Entity.Database.SetInitializer(new System.Data.Entity.MigrateDatabaseToLatestVersion<MyPackageDbContext, MyPackage.Migrations.Configuration>());
        return View();
    }

In my Configuration class for the migrations I have:

public Configuration()
    {
        AutomaticMigrationsEnabled = true;
    }

I have to say that in my way to do all of this I've found a few strange behaviors. One thing that surprises me is this, I don't know if this is normal, read the secuence:

  1. Package installed with new migrations but database not up to date. So if I access the EF this affected by this I get the exception about this. Ok up to this.
  2. I go to my action /MyPackage/Admin/Update and run it. Apparently it runs. I go to the database and I don't see changes. Even the migrations table does not have a new row.
  3. I access again the EF part that displayed the exception before (point number 1) and then everything goes through, database is updated and the migrations table shows the new line.

One thing that you have to notice is that the Configuration class is internal, but because this is a module I needed to be accessible from another assembly. I tried to make it public but I got some strange warnings/errors that I don't know if they are related. So in the end I kept it internal but used 

[assembly: System.Runtime.CompilerServices.InternalsVisibleTo("OtherAssembly")]

I've found a few of strange behaviors in Visual Studio with all this stuff of the NuGet packages, CF, migrations ... I don't know if these things are bugs, but all this thing took me two full working days.

I hope it is useful for any other that wants to create a CF NuGet package that is updateable.

Upvotes: 2

marvc1
marvc1

Reputation: 3699

In package manager console you will need to the Default project to MyProject.EntityFramework

You may also need to make sure MyProject.Web.UI is set as the start up project (in case there are multiple), then you can pass in the connection string into update command:

Update-Database -ConnectionStringName MyConnStringName

This should update the database correctly, unless there is data that will be lost.

Upvotes: 1

Joey Gennari
Joey Gennari

Reputation: 2361

If your DbContext is in MyProject.EntityFramework then the Default Project in the Package Manager Console needs to be set to MyProject.EntityFramework before you can use Update-Database.

Upvotes: 0

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