EF 5,Code First - 创建一个新数据库并以编程方式运行所有迁移

Question

我正在使用Entity Framework Code First迁移,我有一个场景,我想运行一套集成测试.每次测试运行时,我都想重新创建数据库,并应用所有迁移

步骤应该是:

1. 删除现有的测试数据库(如果有)
2. 创建新的测试数据库,并应用所有迁移
3. 种子数据

这是我已添加迁移的现有项目,我使用Enable-Migrations命令创建"InitialCreate"迁移,其中包含将所有表添加到数据库的代码.

我的自定义中的代码IDatabaseInitializer如下:

public void InitializeDatabase(MyContext context)
{
    //delete any existing database, and re-create
    context.Database.Delete();
    context.Database.Create();            

    //apply all migrations
    var dbMigrator = new DbMigrator(new Configuration());
    dbMigrator.Update();

    //seed with data
    this.Seed(context);

    context.SaveChanges();
}

在Up我InitialCreate迁移的方法是没有得到这个代码,这不是我所期待调用.而是在Database.Create()调用方法时创建所有表.我需要运行InitialCreate迁移,因为我在那里有额外的代码来创建存储过程.

所以我的问题是,如何以编程方式创建新数据库并运行所有迁移(包括InitialCreate迁移)？

Answer 1

以下代码使我能够满足问题中概述的集成测试场景的需求,但肯定有更好的方法吗？

public void InitializeDatabase(MyContext context)
{
    //delete any existing database, and re-create
    context.Database.Delete();

    var newDbConnString = context.Database.Connection.ConnectionString;
    var connStringBuilder = new SqlConnectionStringBuilder(newDbConnString);
    var newDbName = connStringBuilder.InitialCatalog;

    connStringBuilder.InitialCatalog = "master";

    //create the new DB
    using(var sqlConn = new SqlConnection(connStringBuilder.ToString()))
    {
        using (var createDbCmd = sqlConn.CreateCommand())
        {
            createDbCmd.CommandText = "CREATE DATABASE " + newDbName;
            sqlConn.Open();
            createDbCmd.ExecuteNonQuery();
        }
    }

    //wait up to 30s for the new DB to be fully created
    //this takes about 4s on my desktop
    var attempts = 0;
    var dbOnline = false;
    while (attempts < 30 && !dbOnline)
    {
        if (IsDatabaseOnline(newDbConnString))
        {
            dbOnline = true;
        }
        else
        {
            attempts++;
            Thread.Sleep(1000);
        }
    }

    if (!dbOnline)
        throw new ApplicationException(string.Format("Waited too long for the newly created database \"{0}\" to come online", newDbName));

    //apply all migrations
    var dbMigrator = new DbMigrator(new Configuration());
    dbMigrator.Update();

    //seed with data
    this.Seed(context);

    context.SaveChanges();
}

private bool IsDatabaseOnline(string connString)
{
    try
    {
        using (var sqlConn = new SqlConnection(connString))
        {
            sqlConn.Open();
            return sqlConn.State == ConnectionState.Open;
        }
    }
    catch (SqlException)
    {
        return false;
    }
}