I have an existing Ef DbContext (ApplicationDbContext) that connect to a MySql server with it's proper OnConfiguring and OnModelCreating function.
Now I must add a new DbContext (GeoDbContext) to a different server.
I add the GeoDbContext in services
.AddDbContext<ApplicationDbContext>(m => m.UseMySql(ApplicationConn, ServerVersion.AutoDetect(ApplicationConn)))
.AddDbContext<GeoDbContext>(m => m.UseNpgsql(GeoConn))
In the GeoDbContext, with its own OnConfiguring and OnModelCreating function, I defined a new DbSet property
public DbSet<UserLocation> Locations { get; set; }
Then I exec the Add-Migration , and this is my problem.
Specifying I want to use the GeoDbContext
Add-Migration addLocation -Context GeoDbContext
I receive an error about properties existing in the ApplicationDbContext, already correctly configured in the ApplicationDbContext OnModelCreating function.
The entity type (omissed) has multiple properties with the [Key] attribute. Composite primary keys can only be set using 'HasKey' in 'OnModelCreating'.
I want add a migration only for the GeoDbContext.
How to correctly configure it?
As #KirkWoll wrote in the comment
This usually happens because one or more of the entity types (i.e. UserLocation) has relationship properties (either single or collection) with types that are in the other database.
Remove the navigation property from the model did the work.
In my project, for some reason i have two separate repositories (with different DbContext and schema). Now, i need to create a foreign key from one model class inDbContextB to another model class in DbContextA, assuming that DbContextA is already applied to database.
//This is a code snippet in DbContextB.IEntityTypeConfiguration<ModelClassB>() method.
builder
.HasOne(col => col.PropertyA)
.WithOne()
.HasForeignKey<ModelClassB>(col => col.PropertyAId)
.IsRequired();
The problem is, DbContextB will automatically create a table for ModelClassA while this table is already existed, because i run DbContextA migration script first.
However, One way to achieve this is to manually insert the foreign key into generated migration script (ModelClassB.PropertyAId is enough for me and i don't care about its navigation property ModelClassB.PropertyA).
The question is: How can i force DbContextB to add a foreign key without need to add its corresponding table?
For EF Core < 5.0, the general approach for this scenario has been to use a special context only for migrations, that contains all model classes and relationships. Your app would not use this special context.
From Ability to exclude/skip/ignore parts of the model from migrations so that a table is not created (for overlapping bounded contexts)
#2725 on GitHub:
I just found a workaround
Create another DbContext that inherit your DbContext, for example MigrationDbContext. Override the OnModelCreating method and ingore entities that you want it's table not being generated.
protected override void OnModelCreating(ModelBuilder builder)
{
base.OnModelCreating(builder);
builder.Ignore<Category>();
}
Create another class that implement IDbContextFactory. For example
public class MigrationContextFactory : IDbContextFactory<MigrationDbContext>
{
public MigrationDbContext Create()
{
var optionsBuilder = new DbContextOptionsBuilder<MigrationDbContext>();
optionsBuilder.UseSqlite("Data Source=blog.db");
return new MigrationDbContext(optionsBuilder.Options);
}
}
The migration tool will discover this MigrationContextFactory and use the MigrationDbContext.
For EF Core >= 5.0, version 5.0.0-rc1 introduces the brand new Relational:IsTableExcludedFromMigrations annotation, that you can set e.g. by using the new entity.ToTable(string name, bool excludedFromMigrations) Fluent API extension method overload.
look at this question for example.
Entity Framework (EF) Code First Cascade Delete for One-to-Zero-or-One relationship
I have a normal context etc.
If i change anything, i can generate a new migration per Add-Migration test.
But if i change WillCascadeOnDelete() from true to false or adding some with true it is ignored by entity framework.
I'm using Code first with a generated model from database.
In the generated model everything was on WillCascadeOnDelete(false).
So now I'm changing it from false to true but its ignored by entity framework.
I tried this: http://msdn.microsoft.com/en-us/data/jj591620.aspx#CascadeDelete too.
After adding this lines ... Nothing changes if i add Add-Migration newTest.
modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>()
modelBuilder.Conventions.Remove<ManyToManyCascadeDeleteConvention>()
This is ignored, too, by Add-Migration thirdTest.
modelBuilder.Conventions.Add<OneToManyCascadeDeleteConvention>()
modelBuilder.Conventions.Add<ManyToManyCascadeDeleteConvention>()
I can change everything with WillCascadeOnDelete... It is ignored!
If i change everything else, it works and would be appended in new Migrations...
The main class for this construct is the following.
[Table("SomeToThing")]
public class SomeToThing : Base
{
[Column("Some")]
public Guid SomeId { get; set; }
[ForeignKey("SomeId")]
public virtual Some Some { get; set; }
[Column("Thing")]
public Guid ThingId { get; set; }
[ForeignKey("ThingId")]
public virtual Thing Thing { get; set; }
}
I have this tables:
Some
SomeToThing
Thing
The SomeToThing has additional variables and because that i can't map Some directly to Thing.
I know this thread is old, but I was just having the same issue.
My solution was to delete the migration source file and re-scaffolding it from scratch.
On my first try I forgot to set .WillCascadeOnDelete(false), and for good reasons, SQL Server rejected the migration due to cycles. Then when I tried to re-scaffold the migration using the same name after removing cascades in the OnModelCreating method, EF just wouldn't pick up those particular changes.
Then I deleted the migration source file and ran Add-Migration SameMigrationName. Cascade deletes were removed, and seems like it worked, since MSSQL accepted the migration script. I'm using EF 6.1.3 btw.
One thing I would like to mention, relating to the problem I was having, was that I added the following code (to my 'OnModelCreating', ie DbContext):
modelBuilder.Entity<MyEntityTwo>()
.HasMany(e => e.MyEntityOne)
.WithRequired(e => e.MyEntityTwo)
.HasForeignKey(e => e.MyEntityTwoId)
.WillCascadeOnDelete(false);
but I added this AFTER the table defining MyEntityOne was already defined, ie in a previous migration.
Turns out that since I added this to OnModelCreating after the table was already defined, entity framework did 'not' pickup the willcascadeondelete(false) when I added a new migration.
To fix this, I had to manually add the following to (new) migration:
DropIndex(...this was created by EF for me already. Not important...);
DropForeignKey("MyEntityOne", "<name of Foreign key goes here ie FK_MyEntityOne_...etc>");
AddForeignKey("MyEntityOne", "MyEntityTwoId", "MyEntityTwo", "Id", cascadeDelete:false);
AlterColumn(...this was created by EF for me already. Not important...);
CreateIndex(...this was created by EF for me already. Not important...);
By adding the AddForeignKey line, with cascadeDelete: false, it will re-apply the foreign key with cacade on delete false this time.
-----edit-----
I have my code working now. I tried making the relationship one-to-many and it works now by using:
newInspection.Sites.Add(newSite)
The Unique Key constraint is still present in the database, so I'm not completely comfortable with this as being the "answer" since it's more of a work around. I have no idea how to make the one-to-one work, as every time I have tried it (with other tables too for testing purposes) it always gives me this error.
----/edit-----
I am using EF 6 Code First for an application I am developing. I used the EF 6.1 tools to reverse engineer the code first model. I am running into a problem with a 1-to-1 relationship when trying to add new items to the database.
Here is the object that's causing a problem:
[Table("childTable")]
public partial class Site
{
[Key]
public int siteID{ get; set; }
public int inspectionID { get; set; }
...
public virtual Inspection inspection { get; set; }
}
The main "inspection" class has a 1-to-1 relationship with the site, and the class is organized like this:
[Table("someTable")]
public partial class Inspection
{
[Key]
public int inspectionID { get; set; }
...
public virtual Site site { get; set; }
}
The context defines this:
modelBuilder.Entity<Inspection>()
.HasOptional(e => e.site)
.WithRequired(e => e.inspection);
I am creating a new "Site" object and setting everything in it except the "siteID" and "inspectionID" properies -- the primary and foreign key respectively. I am adding it to a new "Inspection" object as a navigation property, then adding the "Inspection" to the context and trying to save:
Inspection newInspection = new Inspection
{
...
site = newSite; // Constructed earlier, no explicit ID. ID = 0 if checked
};
using (var db = new Context())
{
db.Inspections.Add(newInspection);
db.SaveChanges();
}
When I call the SaveChanges() I get the "Cannot insert explicit value for identity column in table '--------' when IDENTITY_INSERT is set to OFF."
I cannot understand why it is doing this, so I used db.Database.Log to check out the SQL being generated, and it is trying to pass an ID for the siteID after the "Inspection" insert. That doesn't make sense to me, because if I check the siteID before calling SaveChanges() the ID is 0, as a "new" one should be. However, it is actually trying to insert a number, like 16. I am unsure where it is getting the number. I thought when adding a new item to the context (i.e. db.Inspections.Add()) that it flagged everything in there as new and treated it as such during insert.
I have no idea why it is trying to insert the ID, but it appears to do this for any navigation property that is 1-to-1. That requires setting the navigation property explicitly, as opposed to using the .Add() method. 1-to-many have always worked fine for me (and do in this Context).
Does anyone know why my DBContext is trying to pass the ID?
Entities that have a 1 to 1 relationship should have the same value in the primary key. That means that the primary key in the dependent should also be a foreign key to the principal, and should not be an identity field.
You should change your tables in line with that requirement so that EF can insert the Inspection object then take its new ID and insert that value into the Sites table as the foreign key/primary key.
EF will add the foreign key constraint when you migrate back to a one-to-one but you will need to add sql to the migration to remove the Identity because EF can't do that (yet)
References:
What does principal end of an association means in 1:1 relationship in Entity framework
Do I define a relationship between two entities on the dependent or the principal?
Configuring a Required-to-Optional Relationship (One-to-Zero-or-One)
I have a local database that is currently in it's second version and should now go to it's third version.
The code for the previous migrations was generated by another programmer so I am assuming I am doing something wrong here.
In my model there are around 30 classes, and inside the model folder there is a mapping folder and it contains the mappings for those 30 classes.
So now I added 1 new class in the same manner as those previous classes and then run the add-migration command in the Package Manager Console.
Infortunately I get an empty migration Up() and Down() method.
When I look in the database there is a __migrationHistory available with the previous 2 migrations. If I run my application now, the third migration is also added but obviously the new table is not being created because it's not in the Up() method.
What could I be doing wrong?
I think something is going wrong when scaffolding the previous migrations... It's like it can't find the new Code-First classes I have added.
This is my command:
add-migration "1.2" -verbose -ProjectName "MyEFproject"
I am assuming that the scaffolding doesn't know where to look for the new class... or is this by convention that all model classes are just expected to be in the project?
Result of add-migration:
namespace MyProject.Migrations
{
using System;
using System.Data.Entity.Migrations;
public partial class _1002 : DbMigration
{
public override void Up()
{
}
public override void Down()
{
}
}
}
Sample of new Model Class:
using System;
using System.Collections.Generic;
namespace MyProject.Models
{
public partial class MyTable
{
public string SomeId { get; set; }
public string SomeText { get; set; }
}
}
Sample of new Mapping class
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity.ModelConfiguration;
namespace MyProject.Models.Mapping
{
public class MyTableMap : EntityTypeConfiguration<MyTable>
{
public MyTableMap()
{
// Primary Key
this.HasKey(t => t.SomeId);
// Properties
this.Property(t => t.SomeText)
.IsRequired()
.HasMaxLength(30);
// Table & Column Mappings
this.ToTable("MyTable", "database");
this.Property(t => t.SomeId).HasColumnName("SomeId");
this.Property(t => t.SomeText).HasColumnName("SomeText");
}
}
}
Thank you,
You need to add your table to your implementation of the DbContext class, e.g.
public class MyDatabaseEntities : DbContext {
public virtual DbSet<MyTable> MyTable { get; set; }
}
While rolling back an existing EF Core Data Context back to empty, my migrations wouldn't generate until I removed the ApplicationDbContextModelSnapshot that accompanied the migrations.
This class is auto-generated and needs to align with your current migration level.
I was able to fix this issue by deleting a record of last migration from _MigrationHistory table.
This record had been incorrectly created before I added DbSet for new model object to DbContext class.
After this deletion new migration was created with correct Up() and Down() methods.
I had this problem because I forgot to add {get; set;} after my variable names
You need to add your table to your implementation of the DbContext class, e.g. While rolling back an existing EF Core Data Context back to empty, my migrations wouldn't generate until I REMOVED the ApplicationDbContextModelSnapshot that accompanied the migrations.
In my case, the datacontext project is a class lib project. It is different from the startup project which is asp.net mvc 5 project. Now by mistake the connection string in the startup project is pointing to a different database.
So ensure that datacontext project and startup project point to the same database. Also use the full command as mentioned in the question like the following. You can include -Force as well.
add-migration "InitialMigration" -verbose -ProjectName "MyEFproject" -Force
Also: Make sure any new properties you've added are public!
In my case I was doing a migration where I added fields to an existing table and was ending up with empty Up and Down methods,
I had something like this:
public bool ExistingField { get; set; }
bool NewField { get;set; }
Can you spot the difference...?
If you make this mistake rerun the migration with the same name (you probably will need to add the -Force parameter to scaffold it full).
PS. Always make sure your project builds fully before attempting to do any kind of EF command. If your project doesn't already build you're asking for trouble.
You need to add your MyTable in Dbset and your issue will be resolved:
public DbSet<MyTable> MyTables { get; set; }
I was getting empty migrations added when I had mistakenly related two tables using a 1-many relationship rather than a many-many (i.e. i forgot one of the navigation properties). I had a seeding file that was expecting a many-many relationship and was subsequently failing during the migration causing the migration to fail. Unfortunately there was no output that made it obvious that was the problem and it was only by using the Entity Framework Power Tools (v4 but installed in VS2015) did i visually see the incorrect relationship and realize it was probably the cause.
I had to Update-Database with the latest migration before the empty one appending this parameter -TargetMigration:"{your-migration-name}".
Probably it will tell you that there will be data loss from the next buggy one we tried. If you can afford it append -Force to it.
Then I tried to add my new Add-Migration and it wasn't empty.
Final thing that you may need to do if above is throwing exception is to go SQL Server Management Studio and delete the last Automatic migration and try to add it again.
if new tables added to Context
just remove new table in "Migration/ExampleContextModelSnapshot"
I had the same issue on EFcore. When renaming Phone -> mobile, the migration came up empty.
My DbContext :
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<MyUser>()
.Property(c => c.Mobile)
.HasColumnName("phone");
}
Problem was using .HasColumnName("phone") was overriding the actual property name so EF probably couldn't see any change.
Changing string value made it work.
I had this exact issue after I wanted to add an extra column to my database. Because my data would not seed unless the tables were empty, I deleted all the tables and the migrations to recreate the tables. When I tried to migrate, the migration had empty up and down methods.
I solved this by deleting the snapshot file as this was creating the issue. So I deleted all the migrations and the snapshot file, added the migration again and ran update database. The tables and migrations were successfully updated with my new column.
A better way to do this though is to run the down method and drop the tables like that if you are working on test data. Obviously this is bad in the real world to drop tables.
To me the problem was that Id property that should correspond to table id was named FeedbackId.
I changed to "Id" and then Up/Down weren't empty anymore.
Dunno if that can help somehow
If your project is small, i.e. you do not have too many migrations yet, you can delete all from your Migration folder. After that, add the migrations again.
I think this also happens when u try to do migration without any changes in the models. eg when you do migration one and succeed, when u try to do migration2 without doing any changes in any of the models, it will create empty UP and Down.
From the perspective of a complete Entity Framework (Core) beginner:
Create your class which will become your table
You can have subclasses with many-to-many or one-to-one relationships.
In step 3 you see the context where both properties have a one-to-one relationship.
Ensure you have one DbContext
If you have more than one DbContext you need to specify which context you want to add the migration to with the -Context parameter.
Add your class to your DbContext as shown by #CondingIntrigue
As a reference The Entity Framework Core DbSet
public class AccountContext : DbContext
{
public DbSet<Account> Accounts { get; set; }
public DbSet<SecretIdentity> SecretIdentity { get; set; }
}
Enter Add-Migration
In my case, I was encountering similar problems with Visual Studio Code.
I have fixed these by doing the following:
Check inside your ContextModelSnapshot : ModelSnapshot
Comment Model Entity Definition…
Delete your migration files related to these entity
Delete the migrations from the dbo.__EFMigrationsHistory table
Compile your solution.
Run the following commands:
dotnet ef migrations add migrationName -p ProjectContainer/
dotnet watch run
Temprorary remove
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
}
and then do initial create
Add-Migration InitialCreate
If after adding your class in the dbContext and your migration is still empty: do the following:
In your DbContextModelSnapshot class, remove every related code to that class name that you are trying to apply add-migration on. Save the DbContextModelSnapshot.cs and use the Add-Migration "Added_filename"
This work for me.
In my case ,I deleted Migration folder completely. As long as I didn't remove the "ApplicationDbContextModelSnapshot" and all previous migrationas it didn't work.
For me it was because I hadn't add Configuration files.
onModelCreating:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.ApplyConfigurationsFromAssembly(typeof(AppDbContext).Assembly);
}
and add configurations in same assembly derived from IEntityTypeConfiguration<T> where T is your model.
I missed adding
{get;set}
After adding getter and setter, up and down methods are not empty.