如果基于Entity Framework代码优先模型不存在，则如何自动生成.mdf db

Question

我编写了模型和上下文类，成功运行了初始迁移，并在我的机器上播种并生成了本地数据库。问题是我正在大学使用Github进行协作项目，而.gitignore文件忽略了.mdf文件（原因很明显）。

我的问题：如果在.mdf文件夹中不存在qzexswpoi SQL Server数据库文件，有没有办法在app启动时自动生成和播种？

我的上下文类看起来像这样：

App_Data

连接字符串如下：

public class ABFContext : DbContext
{
    public ABFContext() : base("ABFDatabase")
    {
        Database.SetInitializer(new CreateDatabaseIfNotExists<ABFContext>());
    }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
    }

    public DbSet<BasketItem> BasketItems { get; set; }
    public DbSet<Catalogue> Catalogues { get; set; }
    // other entities omitted for clarity
}

迁移配置种子数据：

<connectionStrings>
    <add name="DefaultConnection" 
         connectionString="Data Source=(LocalDb)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\aspnet-ABF-20190304080703.mdf;Initial Catalog=aspnet-ABF-20190304080703;Integrated Security=True" 
         providerName="System.Data.SqlClient" />
</connectionStrings>

Answer 1

在EF 6上：使用Database.SetInitializer方法。 （未经测试的代码）

 internal sealed class Configuration : DbMigrationsConfiguration<ABF.DAL.ABFContext>
{
    public Configuration()
    {
        AutomaticMigrationsEnabled = false;
    }

    protected override void Seed(ABF.DAL.ABFContext context)
    {
        context.CustomerRoles.AddOrUpdate(x => x.Id,
              new CustomerRole() { Id = 1, Role = "Member - Current" },
              new CustomerRole() { Id = 2, Role = "Member - Previous" },
              new CustomerRole() { Id = 3, Role = "Customer" },
              new CustomerRole() { Id = 4, Role = "Sponsor" },
              new CustomerRole() { Id = 5, Role = "Staff/Volunteer" }
              );

        // other seed data omitted for clarity
    }
}

class MyInitializer : IDatabaseInitializer<MyContext>
{
    public void InitializeDatabase(MyContext context)
    {
        if (context.MyEntities.Any()) return;

        // add entities here
    }
}

SetInitializer doc：

class MyContext : DbContext
{
    public MyContext()
    {
        Database.SetInitializer(new MyInitializer());
    }
}

IDatabaseInitializer doc：https://docs.microsoft.com/en-us/previous-versions/visualstudio/gg679461(v=vs.113)

Answer 2

通过将https://docs.microsoft.com/en-us/dotnet/api/system.data.entity.idatabaseinitializer-1?view=entity-framework-6.2.0添加到上下文类，我能够实现这一目标：

Database.Initialize(true);

将连接字符串修改为：

public class ABFContext : DbContext
{
    public ABFContext() : base("ABFDatabase")
    {
        Database.SetInitializer(new CreateDatabaseIfNotExists<ABFContext>());
        Database.Initialize(true);
    }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
    }

    public DbSet<BasketItem> BasketItems { get; set; }
    public DbSet<Catalogue> Catalogues { get; set; }
}

并在程序包管理器控制台中运行

<add name="ABFDbConnection" 
     connectionString="Data Source=(LocalDb)\MSSQLLocalDB;Integrated Security=True" 
     providerName="System.Data.SqlClient" />
</connectionStrings>

EF命令。这使用相同的代码优先模型在另一台机器上播种并生成update-database SQL Server数据库文件。