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.
Related
I have a code first model, e.g.:
public class Cars
{
public int Id { get; set; }
public string Brand { get; set; }
}
My DBContext looks like this:
public class TestDbContext : DbContext
{
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.UseSqlite("Data Source = data.db");
}
DbSet<Car> Cars { get; set; }
}
Now when I call "context.Database.Migrate" a _EFMigrationHistory table gets created but no migrations are happening. No tables or columns get created.
And when I call "update-database" in the command line it says "No migrations were applied. The database is already up to date." although there is a "Cars" table to add
What am I doing wrong?
It appears you might have forgotten to create your first migration. Every time you change your object model in a way that needs applied to the database,
you'll need to create a migration - this is not automatic so you can customize the migration code if needed and batch multiple changes into one logical group.
In the package manager console (command line), set your default project to whatever project houses your TestDbContext, and run the add-migration command with a name for the migration, then your project will have a migration to run:
PM> add-migration MyInitalMigration
Package Manager Console Example Image
I would like to add a VIEW to the database, and query the data from this VIEW using L2E. I use migrations for maintaining database schema.
I added one class that should MAP to a VIEW columns. As an example, this class has only two properties
[Table("View_Data")]
public class ViewData
{
[Key]
public int Id { get; set; }
public int PropertyA { get; set; }
}
public class ViewDataMap : EntityTypeConfiguration<ViewData>
{
public ViewDataMap ()
{
this.ToTable("View_Data");
this.HasKey(t => t.Id);
}
}
I added ViewDataMap to OnModelCreating, as with any other Table mappings. I added DbSet ViewDatas.
When I executed
add-migration preview
it created new migration with CreateTable command. Since I do not want to create a table, but only a view, I replaced in UP() CreateTable with Sql("CREATE VIEW...")
Still, EF complains about pending changes in database, and still wants to create new migration with CreateTable()...
How can prevent EF to create new table, but use VIEW instead?
As Steve suggested in the comment, I forgot to do update-database, then all works as expected.
I am using entity framework 6.1. I used code-based migration i.e. Migrate.exe to update my database (Add a new property to table). Migrate.exe executed fine and I did refresh on my SQL Server database but the newly added column was not visible.
I inserted a row into the table and checked table and found that now newly column is added to the table.
I would like to know why this newly created column not visible immediately after executing migrate.exe and why I have to hit database to see my update model changes?
Please respond.
I have used below database context and initializer.
public class AMLDBContext : DbContext
{
public DbSet<Template> Templates { get; set; }
public DbSet<Property> Properties { get; set; }
public AMLDBContext()
{
Database.SetInitializer(new MigrateDatabaseToLatestVersion<AMLDBContext, Migrations.Configuration>());
}
protected override void OnModelCreating(System.Data.Entity.DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Property>().HasKey(s => new { s.PropertyName, s.TemplateId });
modelBuilder.Entity<ReturnAttribute>().HasKey(s => new { s.AttributeName, s.TemplateId });
base.OnModelCreating(modelBuilder);
}
}
I used below command for migrate.exe.
migrate.exe AutoDbUpgrade.exe /StartUpDirectory:"C:\TestProject\AutoDbUpgrade\AutoDbUpgrade\bin\Debug" /startupConfigurationFile=”AutoDbUpgrade.exe.config” /verbose
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>();
}
}
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");
}