I am working on a project that gets connection strings for Entity Framework from environment variables, like this:
public class SomeTests {
[Fact]
public async void TestSomething() {
string connectionString = Environment.GetEnvironmentVariable("APP_CONN_STR");
var appContextOptionsBuilder = new DbContextOptionsBuilder<AppDataContext>();
appContextOptionsBuilder.UseMySql(connectionString); // hardcoded mysql
AppDataContext context = new AppDataContext(appContextOptionsBuilder.Options);
Assert.Equal(context.Country.Count(), 0);
}
}
....
public partial class AppDataContext : DbContext, IAppDataContext
{
public AppDataContext(DbContextOptions options) : base(options)
{
}
public virtual DbSet<Country> Country { get; set; }
...
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Country>(entity =>
{
entity.ToTable("country");
...
});
...
}
}
The code above is a bootstrapper code for some automated integration testing. Historically every developer is using the same old database instance on the network without a problem. I am trying to make these tests run in an isolated environment, so I have set up an empty new mysql database (using docker to make it reproducible), and let Entity Framework to populate it with a schema.
The problem is, when I create an empty database in this mysql instance and give a connection string to that database, then I am getting table not found errors:
connection str: Server=127.0.0.1;Port=3306;Database=app_mysql_db;Uid=root;Pwd=****;
error: MySql.Data.MySqlClient.MySqlException : Table 'app_mysql_db.country' doesn't exist
I found out that EF will not create tables in existing databases, it will only populate a database with tables if EF itself created it. This is the default behavior of EF.
So I tried to remove the database name from the connection string:
connection str: Server=127.0.0.1;Port=3306;Uid=root;Pwd=****;
error: MySql.Data.MySqlClient.MySqlException : No database selected
So how do I let Entity Framework in Code First mode to create my tables?
Related
I first time trying to create web app (.net core 2.1) from scratch with Entity Framework. For some reason I can't get DB generated.
So I installed EF nuget. And did next things:
Added class that inheres from DbContext:
public class ApplicationDbContext:DbContext
{
public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
: base(options)
{
}
public DbSet<Server> Servers { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Server>().HasData(
new Server
{
Name = "My Server",
InUse = false
}
);
}
}
And created Entity:
public class Server
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
public string Name { get; set; }
public bool InUse { get; set; }
}
In startup.cs in ConfigureServices method I added:
var connectionString = Configuration.GetConnectionString("ApplicationConnection");
services.AddDbContext<ApplicationDbContext>
(options => options.UseSqlServer(connectionString));
Connection string coming from appsettings and I debugged it so it does coming through, and it same string that I using in other projects with just different Database name value and it should be ok.
Also I run from console Add-Migration command so I got Migrations folder with InitialCreate migration and some snapshot file.
But when I run app I don't get any error but it never hit break point inside InitialCreate.cs migration and so never create DB.
Any ideas where and what should I call to trigger those?
If you want entity framework automatically creates your database
In Configuration file, add this line in constructor:
AutomaticMigrationsEnabled = true;
Then add the code into DBContext:
Database.SetInitializer(new
DropCreateDatabaseAlways<YourDbContext>());
Then when the application already ran:
Database.SetInitializer(new
DropCreateDatabaseIfModelChanges<YourDbContext>());
You can also have a look MigrateDatabaseToLatestVersion
If you manually track version of database:
Update AutomaticMigrationsEnabled = false;
From console, run command Update-Database to migrate your database
manually
So I been able to create DB by adding next code inside Startup.cs in Configure() method
using (var scope = app.ApplicationServices.CreateScope())
{
var dbContext = scope.ServiceProvider.GetRequiredService<ApplicationDbContext>();
dbContext.Database.Migrate();
if (!dbContext.Servers.Any())
{
dbContext.Servers.Add(new Server
{
Name = "My Server",
InUse = false
});
dbContext.SaveChanges();
}
}
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.
When I execute my web app and try to save data into databse, this exception happens :
Model compatibility cannot be checked because the database does not
contain model metadata. Model compatibility can only be checked for
databases created using Code First or Code First Migrations.
I try lot of issue for resolve this problem , but it persist yet !!
Using migrations isn't really necessary if you're developing on your local machine. You can just set the database Initializer to drop the database always, run some code that interacts with the database, and then you'll see that the database will be recreated and the error will be gone.
Should work, that's how I do it.
delete the database manually, then restart the project with:
public class DbDataContext : DbContext
{
public IDbSet<FlightType> FlightTypes { get; set; }
public DbDataContext()
{
//Validates if database Exists or if is CompatibleWithModel
//Using when Databes is productive - use code first migrations for db changes in this case
//Database.SetInitializer(new ValidateDatabase<DbDataContext>());
//Custom Initializer - crates databse with required entries
//Using while developing
Database.SetInitializer<DbDataContext>(new DatabaseInitializer<DbDataContext>());
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
}
}
DatabaseInitializer:
public class DatabaseInitializer<T> : DropCreateDatabaseIfModelChanges<DbDataContext>
{
protected override void Seed(DbDataContext dbDataContext)
{
dbDataContext.FlightTypes.Add(new FlightType { FlightTypeNummer = "axd", Name = "AXD_LX", IsDefault = true });
base.Seed(dbDataContext);
}
}
ValidateDatabase:
public class ValidateDatabase<TContext> : IDatabaseInitializer<TContext> where TContext : DbContext
{
public void InitializeDatabase(TContext context)
{
if (!context.Database.Exists())
{
throw new InvalidOperationException("Database does not exist");
}
if (!context.Database.CompatibleWithModel(true))
{
throw new InvalidOperationException("The database is not compatible with the entity model.");
}
}
}
Are you trying to use Code-First Migrations? If so, have you run the following command in the Package Manager Console?
PM> Enable-Migrations
I am creating an Entity Framework Code-First model to execute ad-hoc queries against a SQL Server database. I am not including any tables/views from the "dbo" schema in my EF model; instead I am only including tables/views from the "model" schema in my database. I do have duplicate names of objects in my database that are separated only by schema (e.g. "dbo.Child" and "model.Child").
Is there one line I can specify in the DbContext that will say in essence "map all entities in this context to the 'model' schema"? I know that I can map each entity to the proper schema (see below), but I'd like to avoid listing out every entity in my database again.
This is what I know I can do:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Child>().ToTable("Child", "model");
modelBuilder.Entity<Referral>().ToTable("Referral", "model");
// 100 lines later...
modelBuilder.Entity<Exit>().ToTable("Exit", "model");
}
This is what I'd like to do:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Conventions.Add(new MapAllEntitiesToSchemaConvention("model"));
}
I couldn't find anyway to do this out of the box in EF 4.2, but I needed all my entities to be in a different schema so I hacked this up in an attempt to keep things DRYer. It uses the same underlying pluralization engine as EF, and the overrides are there incase entities need to specify the table name.
A reference to System.Data.Entity.Design is needed.
public class BaseConfiguration<TEntityType> : EntityTypeConfiguration<TEntityType> where TEntityType : class
{
private readonly static PluralizationService ps = PluralizationService.CreateService(new CultureInfo("en-US"));
public BaseConfiguration() : this(ps.Pluralize(typeof(TEntityType).Name)) { }
public BaseConfiguration(string tableName) : this(tableName, MyContext.Schema) { }
public BaseConfiguration(string tableName, string schemaName)
{
ToTable(tableName, schemaName);
}
}
I define the schema name via a constant string in MyContext, ie:
public class MyContext : DbContext
{
public const string Schema = "my";
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Configurations.Add(new SnapshotConfiguration());
}
}
And my entities configurations look like:
public class SnapshotConfiguration : BaseConfiguration<Snapshot>
{
...
}
Caveat: I still need configuration's for each entity I want in the correct schema - but the jist of it could be adopted elsewhere.
i am using the Ado.Net Entity Framework with Code Only (Tutorial at: ADO.NET team blog) and i want to be as much database independent as possible.
In my first approach i just want to go for Sql Express and Sql Compact databases.
With Sql Express everthing works fine but with Sql Compact i get the exception mentioned in my question.
Does anybody knows if it is possible to connect to Sql Compact with the Code Only approach? (with a generated .edmx file for a Sql Compact database everthing works fine, but i want to use code only!)
Here is some code:
My Class which is building the DataContext:
public class DataContextBuilder : IDataContextBuilder
{
private readonly DbProviderFactory _factory;
public DataContextBuilder(DbProviderFactory factory)
{
_factory = factory;
}
#region Implementation of IDataContextBuilder
public IDataContext CreateDataContext(string connectionString)
{
var builder = new ContextBuilder<DataContext>();
RegisterConfiguration(builder);
var connection = _factory.CreateConnection();
connection.ConnectionString = connectionString;
var ctx = builder.Create(connection);
return ctx;
}
#endregion
private void RegisterConfiguration(ContextBuilder<DataContext> builder)
{
builder.Configurations.Add(new PersonConfiguration());
}
}
The line
var ctx = builder.Create(connection);
is throwing the exception.
The IDataContext is just a simple Interface for the ObjectContext:
public interface IDataContext
{
int SaveChanges();
IObjectSet<Person> PersonSet { get; }
}
My connection string is configured in the app.config:
<connectionStrings>
<add name="CompactConnection" connectionString="|DataDirectory|\Test.sdf"
providerName="System.Data.SqlServerCe.3.5" />
</connectionStrings>
And the build action is started with
var cn = ConfigurationManager.ConnectionStrings["CompactConnection"];
var factory = DbProviderFactories.GetFactory(cn.ProviderName);
var builder = new DataContextBuilder(factory);
var context = builder.CreateDataContext(cn.ConnectionString);
I have to answer my own question.
This works now with the
Entity Framework CTP 4
and
SQL Server Compact 4.0