EntityFramework 代码优先的自定义连接字符串和迁移 [英] EntityFramework code-first custom connection string and migrations

问题描述

当我使用默认连接字符串(从 app.config 读取)创建上下文时，会创建数据库并且迁移工作 - 基本上一切正常.而当以编程方式创建连接字符串时(使用 SqlConnectionStringBuilder):

When I create a context with a default connection string (as read from the app.config) the database is created and the migrations work - basically everything is in order. Whereas when the connection string is created programatically (using SqlConnectionStringBuilder):

• 当数据库不存在时不创建数据库(场景A)；
• CreateDbIfNotExists() 创建最新版本的数据库模型，但迁移机制未被调用(场景B).

• database isn't created when the database is not present (scenario A);
• CreateDbIfNotExists() creates the newest version of database model but the migration mechanisms are not invoked (scenario B).

在 A 中，当我希望访问数据库时会抛出异常，因为 - 显然 - 它不存在.在B 数据库中创建了正确的迁移机制没有调用，就像标准连接字符串中的情况一样.

In A an exception is thrown when I wish to access the database, as - obviously - it isn't there. In B database is created properly migration mechanisms are not called, as is the case in standard connection string.

app.config:"Data Source=localhost\SQLEXPRESS;Initial Catalog=Db13;User ID=xxx;Password=xxx"

建造者:

sqlBuilder.DataSource = x.DbHost;
sqlBuilder.InitialCatalog = x.DbName;
sqlBuilder.UserID = x.DbUser;
sqlBuilder.Password = x.DbPassword;

初始化器:

Database.SetInitializer(
    new MigrateDatabaseToLatestVersion<
        MyContext,
        Migrations.Configuration
    >()
);

规格:实体框架:5.0，数据库:SQL Server Express 2008

Specs: Entity Framework: 5.0, DB: SQL Server Express 2008

推荐答案

如果您的迁移无法正常工作，请尝试在 DbContext ctor 中设置 Database.Initialize(true).

If your migration does not work correctly try to set Database.Initialize(true) in DbContext ctor.

public CustomContext(DbConnection connection)
: base(connection, true)    
{    
        Database.Initialize(true);    
}    

我有类似的迁移问题.在我的解决方案中，我必须始终在 ctor 中设置数据库初始值设定项，如下所示

I have similar problem with migrations. And in my solution I have to always set database initializer in ctor, like below

public CustomContext(DbConnection connection)
: base(connection, true)    
{    
        Database.SetInitializer(new CustomInitializer());
        Database.Initialize(true);    
}    

在自定义初始值设定项中，您必须实现 InitalizeDatabase(CustomContex context) 方法，例如.

In custom initializer you have to implement InitalizeDatabase(CustomContex context) method, eg.

class CustomInitializer : IDatabaseInitializer<CustomContext>
{
    public void InitializeDatabase(CustomContext context)
    {
        if (!context.Database.Exists || !context.Database.CompatibleWithModel(false))
        {
            var configuration = new Configuration();
            var migrator = new DbMigrator(configuration);
            migrator.Configuration.TargetDatabase = new DbConnectionInfo(context.Database.Connection.ConnectionString, "System.Data.SqlClient");
            var migrations = migrator.GetPendingMigrations();
            if (migrations.Any())
            {
                var scriptor = new MigratorScriptingDecorator(migrator);
                string script = scriptor.ScriptUpdate(null, migrations.Last());
                if (!String.IsNullOrEmpty(script))
                {
                    context.Database.ExecuteSqlCommand(script);
                }
            }
        }
    }
}

更新

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