I am using Entity Framework 5.0 Data migrations along with code first.
When i add a new field to my model and execute the following command in the package manager console.
"Add-migration AddedField"
All I get is an empty migration called "n_AddedField", the up and down methods contain no logic.
I tried a bunch of things, reinstalling the EF nuget package, cleaning my solution, rebuilding, manually removing all generated files and directories.
Then i decided that i would scrap all my migrations and start over, and then it got weird.
After deleting all my migrations, and the migrationhistory table in the database, i recreated the database using the CreateDatabaseIfNotExists initializer. After doing this, I should be able to create a new initial migration. But when i try to create create a new migration, I get an error saying that there are pending migrations, and lists all the migrations that i just deleted from my project.
I have no idea why and how EF still has any recollection of those migrations.
I even tried searching through filecontents looking if the migrations were saved somewhere else or something. But nothing..
Data migrations look really neat when scott hansleman demo's it on stage, but for real work, I'm starting to look for alternatives.
When the project started, we were using EF 4.x and a while back switcted to 5.0, but since the switch i have added a bunch of migrations successfully.
Does anyone have any idea how to solve this problem?
Basically i just want to be able to add migrations, and generate a sql script with the changes.
I had a similar problem where a new migration was not being found, and so update-database was giving me the following error no matter what I did:
Unable to update database to match the current model because there are pending changes and automatic migration is disabled. Either write the pending model changes to a code-based migration or enable automatic migration. Set DbMigrationsConfiguration.AutomaticMigrationsEnabled to true to enable automatic migration.
You can use the Add-Migration command to write the pending model changes to a code-based migration.
Doing a "batch clean" solved my problem, suggesting EF was using an old/invalid assembly from a folder other than the currently selected 'solution configuration (e.g. DEBUG)'.
Hope this helps someone else out there.
oops. In my case I was adding a new root entity not referenced by any other entity. The result was simply that code first had no reason to generate a migration for the entity. Once I added the code into the DbContext (a dbset) it worked like a charm.
The problem in my case was caused by:
Create a migration (successfully)
Decide that I want to re-create it, and delete the migration .cs file
Try to regenerate it, and end up with empty migration's Down and Up functions
In this case, I forgot to also delete the ApplicationDbContextModelSnapshot.cs entries for the model changes. Removing the new mappings in this file solved my problem and it then generated correctly.
Just got the same problem but figured out that my new field was added as a member variable and not a property - it was missing the {get; set;} part and that makes migration skip that field.
May not be your case but it might help someone else.
You're 'out of sync' - Db, migrations, code - and you can expect all sorts of problems like that.
I did this million times (almost:) and it works really well - but you need to go steady, and be meticulous with what you're doing.
You can read through this 'summary' I made - start half-way somewhere (but also check connection).
Code first create tables
...and if it doesn't work I'd suggest you make a small 'repeatable' scenario / model - post exactly what you have.
How migrations work:
Migrations are tied to the 'migration table'.
When Add-Migration is run - it checks against the 'existing database' structure and migration table - and makes the 'difference' (sometimes you get none 'up' 'down' simply as too are in sync).
So, each 'migration' is a complex diff in between your code, existing migrations, and database, and migration table. Short of removing the database nothing else is certain to reset - Db 'migration' table may not be enough - that doesn't guarantee full 'cleanup' (if possible, I always do full Db delete). You also need to delete your code migrations.
Make sure to 'compile' the projects (best make them compile automatically in configuration) after/before where relevant.
Make sure your 'connection' matches.
Once all is in sync - all should work nicely - but you gotta keep it in sync. Unless you plan to delete the Db (testing) - don't remove migrations just like that (you can use Update-Database -0 (I think) to get back to some migration (this is 'zero state').
I had a problem similar to this, where using the -force flag on add-migration to re-scaffold an existing migration stopped working for no apparent reason.
No matter what I did I got the stupid "Unable to generate an explicit migration because the following explicit migrations are pending" error message. After trying nearly everything I could think of and stopping just short of smashing my laptop to pieces, out of desperation I ran enable-migrations again and of course got the "Migrations have already been enabled in project 'Blah.Blah'" message. Tried add-migration -force again and magically it was working.
I have no idea what it changed- must have been some user settings/config file outside of source control. Hopefully this will help someone else.
The batch build -> clean option did not work for me.
I solved the problem by:
Creating a migration with 'Add-Migration NameOfMigration'
Deleting the contents of the up and down functions of the created migration class.
Updating the database by running the migration script (which will just add a row to the _MigrationHistory table with 'Update-Database -Verbose'
The web application now runs successfully, so essentially I had an issue that was fixed by adding meta-data only.
It happened to me and nothing worked. Then i did this on my own and everything works now.
Problem:
I created a Model "Cars". And When I create a migration for it using command "add-migartion AddCarModel", a migratoin was created but it was empty. I tried with different names and also tried delete migration's .cs file but nothing worked. Then I did the following:
Solution:
Follow below steps:
1. Delete all the empty migrations that you created for the Model. (But remember the names of the migrations for step 2)
2. Also delete those migration entries from "_MigrationHistory" table.
3. Comment out you line(s) of your model DB context, (in my case it is "public DbSet Cars{ get; set; }")
4. Clean and Rebuild solution. (Its best that if you batch clean)
5. Make sure that your update command is working and not throwing errors. (Command: "update-database -verbose")
6. Now uncomment line(s) that you commented in step 3.
7. Now create the migration for that model. (I created the migration with same name as before)
Hopefully it works. :-)
I added a new class to my data model to a sub-directory, the resultant namespace was not visible to scaffolding using add-migration.
Fix was to rename the namespace of the new class to conform to the rest of model, and/or add "public virtual DbSet .." etc into your entity context class, which will require you to reference this new namespace, then run add-migration again.
It seems that i managed to solve the problem by moving the models and the context class to another project.
I still have no idea why this happened, and this solution is really no solution at all :(
I had the same problem. Migrations were enabled but they weren't detecting any changes.
My solution was to re-enable migrations using -Force attribute and then everything worked.
Enable-Migrations -ProjectName -StartupProjectName --ConnectionStringName -Force
I had to delete the _MigrationHistory table that is generated by EF. Then I ran add-migration again. Be careful with this though, as it will generate the queries needed from scratch, including tables that are already there.
In my case it was because I had added a secondary context 'ApplicationDbContext' as part of the ASP.net identity stuff. When I ran the 'enable-migrations' command again I got an error that there was more than one context. Once I combined the two things started working again.
Maybe the stupidest of all:
I was adding a migration with the same name as the new object I was creating.
I had to run dotnet ef migrations remove even though I'd deleted the previous migration
If you are using fluent api to set up your configurations for the DbSets then you won't have any problems with it
I'm using Entity Framework v4. I have followed the instructions in the Nerd Dinner tutorial. I'm currently in development mode (not released to any higher environments) and would like for tables to be recreated on each new deployment, since the models are still highly volatile and I don't care to retain data. However, this does not occur. Tables are not created/modified, or anything happening to the DB. If I move to a migrations model by using the Package Manager commands: enable-migrations, add-migration (initial), this works and uses my migrations. However, since I don't yet want to have granular migrations and only want my initial create script, I am forced to delete the migrations folder, redo the commands (enable-migrations, add-migration) and delete the database manually, every time I change anything.
How do I get the drop/create behavior of code first to occur?
Use DropCreateDatabaseAlways initializer for your database. It will always recreate database during first usage of context in app domain:
Database.SetInitializer(new DropCreateDatabaseAlways<YourContextName>());
Actually if you want to seed your database, then create your own initializer, which will be inherited from DropCreateDatabaseAlways:
public class MyInitializer : DropCreateDatabaseAlways<YourContextName>
{
protected override void Seed(MagnateContext context)
{
// seed database here
}
}
And set it before first usage of context
Database.SetInitializer(new MyInitializer());
If the database already exists and you want to make changes to your model, you use DropCreateDatabaseIfModelChanges<YourContextName>
I created a Code First class
A database was created in Sql automatically.
I deleted the tables :(
I have migrations enabled:
AutomaticMigrationsEnabled = true;
AutomaticMigrationDataLossAllowed = true;
Database.SetInitializer(new DropCreateDatabaseAlways<SurveyContext>());
Yet upon
update-database -force
Cannot find the object "dbo.CustomerResponses" because it does not exist or you do not have permissions.
Please help.
In system tables there is a table called
__MigrationHistory
...I deleted it.
In Package manager console ran command "update-database"
Problem fixed!
More info:
http://blog.oneunicorn.com/2012/02/27/code-first-migrations-making-__migrationhistory-not-a-system-table/
Daf De Giraf has a better answer here that doesn't wipe out your migration history.
If you worked the correct way to create your migrations by using the
command Add-Migration "Name_Of_Migration" then you can do the
following to get a clean start (reset, with loss of data, of
course):
Update-database -TargetMigration:0
Normally your DB is empty now since the down methods were executed.
Update-database
This will recreate your DB to your current migration
I had that error message in the past....
Check if the database that you've specified in the connection string is created. If it's not, create it and then execute the code.
Obviously there may be a better way of doing this, but as this was surprisingly top Google account I thought it would be good to mention the idea i had after reading these answers:
Here's the issue i faced:
I was changing FK's generated by EF6 code first and came across the error:
Unable to determine the relationship represented by navigation property 'Account.SalaryIncomes' of type 'ICollection<Person>'. Either manually configure the relationship, or ignore this property using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.
I attempted many ways of defining the Mapping in the hopes of resolving this error, however i ended up dropping my Person table, and after removing the the relationship entirely in an attempt to start from scratch, the error was resolved. However when updating the database, it complained that "Person" did not exist - which lead me here.
After reviewing these answers, I decided I was too lazy to reload the data and thought that the migrations generated C# UP() and Down() methods - I thought, maybe i can reference another migration...
after extracting the up and down code into public methods in that migration, and referencing those from the new migration - the update worked and person was then created. Just to be safe - i wrapped the new calls in try catch... do my new UP method looks like this:
protected override void Up(MigrationBuilder migrationBuilder)
{
try
{
new AddPeople().CreatePersonTable(migrationBuilder);
}
catch { }
// Origional generated migration code
}
This answer comes with the caviat that I have not tested to see if this migration will be overridden next time (loosing the code) - however if the migrations are run in order, then pressingly you can in fact run this once, and then remove it after.
I'm trying to update the database on a build server, and it's failing because it's trying to run automatic migrations, even though they're disabled. The database already exists and I just need to apply the latest migration. Here's my context:
public sealed class Configuration : DbMigrationsConfiguration<CableSenseInstanceConfiguratorContext>
{
public Configuration()
{
AutomaticMigrationsEnabled = false;
}
}
I've got a bunch of migration files I've created manually, here's the latest one:
public partial class Settings : DbMigration
{
public override void Up()
{
AddColumn("dbo.MasterInstances", "Settings", c => c.String());
}
public override void Down()
{
DropColumn("dbo.MasterInstances", "Settings");
}
}
If I then manually update the database from the package manager console, I see it tries to run an automatic migration (which fails because the table already exists):
Applying code-based migrations: [201204200805145_NoMoreCerts, 201210311451543_SuperUsers, 201301041036414_Settings, 201301041128583_Settings2].
Applying code-based migration: 201204200805145_NoMoreCerts.
Applying automatic migration: 201204200805145_NoMoreCerts_AutomaticMigration.
My __MigrationHistory table just has the one entry for the initial creation. How can I stop it from doing the automatic migrations?
Check out the answer from jjslagace here:
Update-Database tries to do an automatic migration even with automatic migrations disabled
You are building your migrations manually. My guess is entity framework wants to add something that you don't have in your migration script, or it wants to name columns differently etc. EF has a brain, and that brain is fairly simple. It's expecting things to be a certain way unless you tell it otherwise using fluent (not by manually creating/tweaking migration files). From the answer on the question above it sounds like sometimes that results in the issue you are seeing.
Long story short don't build the migration files manually. Instead run the add-migrations command. This will create the migration for you and you can see what EF is expecting to do before it's applied to your database (because sometimes it's stupid). If you need to override what EF is generating for you add a fluent mapping in your DBContext class by overriding OnModelCreating. Then just run add-migration again with the -force option. Here is a good reference for using the Fluent API to custimize EF mappings. Rinse and repeat until you get the migration you are looking for then run update-database.
Hope that helps!
I have been trying out EF 4.1 (code first) with MVC 3. I am thinking ahead to when the application will need changes. I tested a couple of scenarios. I like the idea of manually editing the database when the model (my POCOs) would changed.
ASP.NET error when I change the model :
"The model backing the 'CTCMContext' context has changed since the database was created. Either manually delete/update the database..."
Now, it says that I can "manually update the database", but I did and still get the same error. Am I missing something !!?!
EDIT
Does this have to do with the model hash generate by EF ?
I have had some struggles with this as well. I found that when you let EF create your database for you that a table named dbo.EdmMetadata is created and this is where/how EF tracks the state of the model. I found that if you delete this table after the database has been initially created you will put things into "manual mode" where you can now manually add/remove columns, tables, etc. from your database and EF will not throw the error that you are seeing.
If however you want to keep having EF update your database as you make changes to your model, you will need to create and call a ContextInitializer class that inherits from either DropCreateDatabaseIfModelChanges or DropCreateDatabaseAlways depending upon the behavior that you want to have happen.
change the class with the new fieldnames, delete the table "EdmMetaData" then recompile your app.
You will be responsible on modifying the fieldname on your views.
it works for me.
As I can see, there aren't really any methods built-in EF for code-first data evolution.
For what was of my initial question, the answer lies in removing the schema generation/validation. It is only then that manually editing the code and database may work.
UPDATE :
EF 5.0 now support migrations
I know this has been marked as solved but in my case it didn't do the trick.
Once I deleted dbo.EdmMetadata I was getting a different error:
Model compatibility cannot be checked because the database does not contain model metadata. Ensure that IncludeMetadataConvention has been added to the DbModelBuilder conventions.
The way it worked for me was to remove the Initializer class from Application_Start:
void Application_Start(object sender, EventArgs e)
{
// MyDB.SetInitializer<MyContext>(new MyInitializer());
}