We have a ef project using an existing legacy database, but adding new tables to it using ef-migrations. For these entities, we create tables using a new schema, to separate them from the legacy tables. We use the convention with plural form of the class name on the db tables.
However, when we add a new class to be mapped to a legacy table (without a plural table name), ef seems to ignore the mapping.
The entity class:
public class Aktor:IVersionedEntityWithId
{
public int Id { get; set; }
public string Navn { get; set; }
public byte[] Version { get; set; }
}
The mapping code:
protected virtual void MapAktor(EntityTypeConfiguration<Tilsyn.Domain.Aktor> config){
config.ToTable("dbo.Aktor");
config.Property(v=>v.Version).IsConcurrencyToken().IsRowVersion();
config.HasKey(e=>e.Id);
}
The exception:
System.Data.EntityCommandExecutionException: An error occurred while
executing the command definition. See the inner exception for details.
---> System.Data.SqlClient.SqlException: Invalid object name 'dbo.Aktors'.
It seems like the sql generated still ad an s to the class name to get the table name. What is missing in this picture? Am I using the ToTable method wrong?
Update: When changing the class name to something other than the table name, it seems to work. When changing the name back again, the problem has vansihed. Is there a EF cache or hidden mapping file somwehere?
Try overriding OnModelCreating() method in your DBContext subclass to create your mappings.
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Tilsyn.Domain.Aktor>().ToTable("dbo.Aktor");
}
Related
What is best/a good practise in the following situation when using TPH inheritance in Entity Framework?:
I have
abstract class Base
{
...
}
class Sub1
{
public int Amount {get;set;}
}
and a DbContext with:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<Sub1>();
}
public DbSet<Base> Bases { get; set; }
Now I add
class Sub2
{
public int Amount { get; set; }
}
and
modelBuilder.Entity<Sub2>();
Before adding Sub2, Sub1.Amount was mapped to a "Amount" column in the Bases table. After adding Sub2, Sub1.Amount is mapped to a "Sub1_Amount" column and Sub2.Amount is mapped to the "Amount" column. The table has data in it, so the new "Sub1_Amount" column are all nulls. When I try to run the system, I get
An exception occurred while reading a database value for property 'Sub1.Amount'. The expected type was 'System.Int32' but the actual value was null.
I understand why this is happening...but I thought Migrations would handle this.
Does anyone one know how to handle this? Thanks!
I have developed a new asp.net Core web application using Visual Studio 2015. I am at the point where I am adding user customization options by adding additional tables to my local database. However I have been unable to add whatever EF needs to query a new table correctly. I get the following error when attempting to query the table..
Applying existing migrations for ApplicationDbContext may resolve this issue
There are migrations for ApplicationDbContext that have not been applied to the database
•00000000000000_CreateIdentitySchema
Apply Migrations
In Visual Studio, you can use the Package Manager Console to apply pending migrations to the database:
PM> Update-Database
Alternatively, you can apply pending migrations from a command prompt at your project directory:
dotnet ef database update
My table is a simple table with a few varchar or nvarchar columns. The model looks something like...
namespace MyNamespace.ColorSchemes
{
public class ColorSchemesViewModel
{
[Required]
public string Id { get; set; }
[Required]
public string Name { get; set; }
[Required]
public string bc { get; set; }
}
Table looks something like this in SQL Server...
CREATE TABLE [dbo].[ColorSchemes](
[Id] [nvarchar](50) NOT NULL,
[Name] [varchar](32) NOT NULL,
[bc] [nchar](7) NOT NULL
)
I have added the table to the application context like such...
public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
public DbSet<ColorSchemesViewModel> Colors { get; set; }
I have also used as separate class similarly like..
public DbSet<ColorSchemes> Colors { get; set; }
public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options) : base(options)
{
}
protected override void OnModelCreating(ModelBuilder builder)
{
base.OnModelCreating(builder);
// Customize the ASP.NET Identity model and override the defaults if needed.
// For example, you can rename the ASP.NET Identity table names and more.
// Add your customizations after calling base.OnModelCreating(builder);
}
}
I have added the context to a controller like this...
private ApplicationDbContext _context;
public MyController(IMemoryCache memoryCache, ILoggerFactory loggerFactory, ApplicationDbContext context)
{
_memoryCache = memoryCache;
_logger = loggerFactory.CreateLogger<ChordMVCController>();
_context = context;
}
I have tried to query the table in my controller like this...
var colorSchemes = (from c in _context.Colors
select c).ToList();
I have attempted to use the Package Manager to per instructions from the error...
PM> Update-Database
I always get this error...
System.Data.SqlClient.SqlException: There is already an object named 'AspNetRoles' in the database.
This doesn't make sense since this table is already in the database and the EF definition. How do I get my table added properly to the EF migrations so I can query it?
I was able to solve this myself...
I created a different context rather than trying to embed the dbset in the default ApplicationDbContext and also removed the onModelCreating method.
public class ColorSchemeDbContext : DbContext
{
public ColorSchemeDbContext(DbContextOptions<ColorSchemeDbContext> options) : base(options)
{
}
public DbSet<ColorScheme> ColorSchemes { get; set; }
}
Replaced the ApplicationDBContext with the new context in my controller class...
private readonly ColorSchemeDbContext _context;
public MyController(IMemoryCache memoryCache, ILoggerFactory loggerFactory, ColorSchemeDbContext context)
{
_memoryCache = memoryCache;
_logger = loggerFactory.CreateLogger<ChordMVCController>();
_context = context;
}
After that the query worked. I spent a lot of time attempting to use the EF migrations to create the tables from a class syntax. Nothing seemed to work. I was creating a new .NET CORE web application in VS 2015 with the template and using user authentication which creates the AspNetRoles tables in SqlLite once you do an update-database. It is very confusing how to add additional tables using a code first approach after that. A lot more documentation is needed regarding EF migrations with respect to managing projects over time. I see the benefits of having all of your database updates maintained from your VS project but it is not easy to understand.
I have a base class
public class BaseClass
{
public int Id {get; set;}
}
and two derived classes
public class Foobar: BaseClass
{
[Required]
public int Whatever {get; set;}
}
public class Snafu: BaseClass
{
[Required]
public int Whatever {get; set;}
}
I'm using Table Per Hierarchy inheritance and trying to cut down on my duplicate columns, so with Fluent API I've mapped them like so:
modelBuilder.Entity<Foobar>().Property(fb => fb.Whatever).HasColumnName("Whatever");
modelBuilder.Entity<Snafu>().Property(sf => sf.Whatever).HasColumnName("Whatever");
However, this results in
(137,10) : error 3023: Problem in mapping fragments starting at line 137:Column BaseClass.Whatever in table BaseClass must be mapped: It has no default value and is not nullable.
In EF6 this type of mapping seems to work fine if I take off the [Required] attribute from both subclasses. Adding a [DefaultValue(0)] attribute to both derived classes does not fix the problem.
Any idea how to get these properties to share a column in the database while maintaining their required attribute?
This is actually a bug in EF6. In EF5 the scenario used not to work at all (we would throw an exception in the lines of "column names need to be unique"). While in EF6 we did some work to enable it, but apparently we missed the fact that the shared column has to be nullable in the database even if the property is required in the derived types. The latter is because unless the base class is abstract, you need to be able to store an instance of the base type and for any instance of the base type the column should be null.
I have filed the issue in our bug database:
https://entityframework.codeplex.com/workitem/1924
Feel free to vote for it.
As for a workaround, if having an intermediary type is not an option, you can mark the column as nullable explicitly appending a call to .IsOptional() on the entity configurations. This won't give you exactly what you want because for the purpose of EF data validation this call to IsOptional() on the fluent API will override the [Required] data annotation. However, other flavors of data validation, such as MVC's validation will still honor the attribute.
There are other possible workarounds that I haven't tried, maybe if it is acceptable to use TPT and have both derived types have Whatever live in a different table this would work. I believe any approach that relies on setting a default value won't help because the bug is not only about the table schema not being able to hold an instance of the base class, it is also about the EF mapping generated by Code First not being valid.
UPDATE: This will be fixed in Entity Framework version 6.1.0 which is currently available in beta.
Introducing another type, which contains the required property shared by the other two accomplishes what you're looking for. The entities then look this:
public class BaseClass
{
public int Id { get; set; }
}
public abstract class BaseIntermediaryClass : BaseClass
{
[Required]
public int Whatever { get; set; }
}
public class Foobar : BaseIntermediaryClass
{
}
public class Snafu : BaseIntermediaryClass
{
}
And the mappings like this:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<BaseIntermediaryClass>().Property(fb => fb.Whatever).HasColumnName("Whatever");
base.OnModelCreating(modelBuilder);
}
Full code of working example can be found here: https://gist.github.com/trayburn/7923392
I have a application using code first; in search section I have to gather information from 3 tables and their related tables so I made a view; and since there is no syntax for code first to create view (I think so; please let me know if I'm wrong) I used pure SQL script;
on model creating to prevent EF to create a table with same name as table (VIEW_SEARCH) I did :
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Ignore<View_Search>();
}
any ways application works fine until you try to get data from the view then BANG...
The model backing the 'SearchContext' context has changed since the database was created. Consider using Code First Migrations to update the database (http://go.microsoft.com/fwlink/?LinkId=238269)
This error simply says that what you have in your model file is inconsistent with what you have in your database.
To make it consistent go to Package Manager Console and type Enable-Migrations, then Add-Migration yourMigrationName and Update-Database. The error should disappear.
If you want to combine data from 3 tables you can simply create a ViewModel.
Let's say you have 3 models: Book, Author, BookStore and you want to have all information in one view. You create ViewModel
public class MyViewModel
{
public Book myBook {get; set;}
public Author myAuthor {get; set;}
public BookStore myBookStore {get; set;}
}
Then you add at the top of your all-in-one-view
#model myNamespace.MyViewModel
and access items like
Model.Book.title
Model.Author.name
Model.BookStore.isClosed
I'm actually working with Entity Framework "Code First" and views, the way I do it is like this:
1) Create a class
[Table("view_name_on_database")]
public class ViewClassName {
// View columns mapping
public int Id {get; set;}
public string Name {get; set;}
// And a few more...
}
2) Add the class to the context
public class ContextName : DbContext {
// Tables
public DbSet<SomeTableClassHere> ATable { get; set; }
// And other tables...
// Views
public DbSet<ViewClassName> ViewContextName { get; set; }
// This lines help me during "update-database" command
protected override void OnModelCreating(DbModelBuilder modelBuilder) {
// Remove comments before "update-database" command and
// comment this line again after "update-database", otherwise
// you will not be able to query the view from the context.
// Ignore the creation of a table named "view_name_on_database"
modelBuilder.Ignore<ViewClassName>();
}
}
I am working on asp.net mvc 4 web api. I am using code first with existing database model. I have a single table in my database so i have the entity class like,
public class Tab1
{
[Key]
public int Field1{get; set;}
public string Field2{get; set;}
}
I have DBContext file like,
public class MyDBContext:DbContext
{
public DbSet<Tab1> Table{ get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
modelBuilder.Entity<Bar>().ToTable("bars");
}
}
and my Get Action is like
public List<Bar> GetTables()
{
MyDBContext context=new MyDBContext();
return context.Table.ToList();
}
But I am getting an error Schema specified is not valid error 0064: Facet 'MaxLength' must not be specified for type 'mediumtext'.. so please guide if i did any mistake in the process.
Here i have one more class like
public class Tab2:Tab1
{
public string Filed3{get; set;}
}
I dont want to create table in database with tab2 since i used tab2 class for returning custom records. I got the above error due to Tab2 inheriting from tab1 when i remove class tab2 it works as usual. so please guide me.
If you problem is only caused when introducing the "Tab2" class in the model and you don't really want "Tab2" to be stored in the database why don't you just annotate the "Tab2" class with the the [NotMapped] attribute or use the fluent configuration ModelBuilder.Ignore.