Is it possible to tell Entity Framework to ignore any custom tables I add to the database. For example, say if I use the sqlmemberhipprovider in the same database as the one used for EF, can I tell EF to just ignore whatever tables I haven't already created classes for? Right now, it's giving the error
"The model backing the 'xxx' context has changed since the database was created. Consider using Code First Migrations to update the database (http://go.microsoft.com/fwlink/?LinkId=238269). "
I don't want EF to do anything on the extra tables it doesn't recognize.
I figured out what I was doing wrong. It wasn't the Membership tables that were causing the problem it was another table I deleted manually that EF was tracking.
Have you tried setting your initializer to null?
Related
I renamed a few tables and some columns. When I run the Add-Migration command, the migration generates code that drops the old tables and columns and adds ones with the new names. This results in losing the data they contained.
Since I don't want to lose the data, I want to edit the migration, removing the drop and add commands, and replacing them with rename commands.
But after I edit a migration, how do I apply that change?
If I run the Update-Database command, that applies it to the database. But not to the snapshot that Entity Framework maintains of my schema (stored in ApplicationDbContextModelSnapshot).
I need a way to incorporate my edits into the model. How can I accomplish this?
So, this is definitely the messy part of code first.
As far as the question asked, as GuruStron suggested, the only way I found to have a valid custom migration is to edit it such that the result is the same as what the original, generated migration produced. This keeps it up to date with the database snapshot. And running Update-Database will run your custom update code.
I think my biggest problem was that I had too many changes going on at once. After struggling with this for a while, I undid some of my changes and added them back bit-by-bit. Entity Framework will rename a table or column if it can figure out that the new name refers to the same column. If it finds many changes, it can't figure this out.
In the end, I had to customize the migration a little for a couple of columns that were being dropped (customized them to be renamed instead). But I was able to get Entity Framework to rename my tables and other columns.
The key: make small changes at a time and carefully review the migration before applying them to the database. If you need to customize the migration, do it such that the end result doesn't change.
You don't.
I suppose you are developing using a code first approach, since the question has this tag on it.
If you are using code first, you must change your models and let Entity Framework change the database schema for you.
Suggested reading:
Migration in Entity Framework Core
Entity Framework Core Migrations
I've got an Entity Framework 6 application. I've ported the database from SQL Server to PostgreSQL. Now when I run the application I'm getting this error:
The model backing the 'ApplicationDbContext' context has changed since
the database was created. Consider using Code First Migrations to
update the database (http://go.microsoft.com/fwlink/?LinkId=238269).
The only thing is that the database schema shouldn't have changed. If it has, there is something wrong with my port which needs fixing. I do not want to run a migration to bring the database up to the new version. I want to find out what the change was that has caused this so that I can correct it.
Does anyone know how Entity Framework decides whether the database is out of date and what causes it to raise this error?
Entity Framework stores migration history and the state of your database model in a table called MigrationHistory.
This document has details on customizing that table.
I suggest not modifying this, however. Instead, as a workaround, you can add a new migration, delete whatever content is inside of the Up() method, and then update your database. This will update the history to match what you currently have.
However when you add the migration, you may want to review the code it produces first to see what EF thinks has changed. It might actually be a legitimate migration.
Edit:
Schema changes are compared against hashes of your SSDL.
I have an odd situation. I am working on a project with a very large existing database that is completely unrelated, but does contain corresponding table id's. It's as if someone copied the database but never related the tables.
In Entity Framework, is there a way to go EF code first and create the relationships in code, but Not apply those relationships in the database? I would like to go through and relate the database but the client doesn't want to pay to fix it.
Thanks!
In this instance, it seems you would be best to add relationships directly to your database (or to a duplicated database for testing/staging) and then just update your entities using your test connection and regression test your app.
I tried finding the answer to this question before posting, but couldn't.
We are using a remote database with Entity Framework and I do not know the approach it was used to create the database. What I would like to do is add a class to the project, add the class to DbSet an create the table automatically. Now, when I use update-database in nuget, i get "migrations not enabled for this database" and its true, there is no configuration file or anything that suggest the approach it was used for creation of this.
I wouldn't want to enable-migrations as I don't want to mess something up or loss data. (or should i?) The existing tables are working fine with the repository...
I created a table manually, added a class that maps the properties by name and hoped that entity framework will pick it up, but no luck.
Here it is in a nutshell: I want to add a new table in a remote database that will be picked up by Entity Framework an generate a class for me. There is also NO .edmx file that can update the model. How was this done then... (?)
I am a new to Entity Framework, so apologies it some of this does not make sense. I am happy to clarify.
Thanks,
Thank you for your responses. I managed to fix this by adding a new class into the repository, using code first approach and then I created a table manually in the database.. The Entity Framework pick it up somehow :)
I was doing this before, but the problem was that I had the DbSet name to plural and database to singular. For instance: Products was the DbSet name and Product table in database. The actual class is still singular.
Thanks again!
I need to use an 'DropCreateDatabaseIfModelChanges' - Initializer class, because I want to create one special entity (table), if it doesn't exist. My problem is, that I've also got another entity in my DbContext, which shouldn't be part of the model compatibility check.
I'm getting the following error message:
Model compatibility cannot be checked because the EdmMetadata type was not inclu
ded in the model. Ensure that IncludeMetadataConvention has been added to the Db
ModelBuilder conventions.
Is there any possibility to exclude a special entity from this check?
EDIT:
I've done what Devart has suggested. The problem seems to be different, than I first tought. It all works fine, if I let EF create a new database with my CheckedContext. But I'm getting the error message above, when I'll try to use my NonCheckedContext wich should use an existing table ...
EDIT2:
This is a working solution. Everything works fine, when the database doesn't exist before. But it's no option for me, to Drop/Create the database.
A possible solution: create a context class inherited from DbContext, and then create two separate subcontexts inherited from the base one - CheckedContext and NonCheckedContext, and set the Database Initialization Strategy accordingly.
Please note that you should access the CheckedContext first so that it fires all its checks.