我已经尝试了一段时间来弄清楚如何使用单个 DBContext 以 Code First 方式创建多个表,但没有任何运气。我确信这只是我对框架的不熟悉,但我不确定我错过了什么。这是一个包含实体和 DBContext 的简单示例。
[Table("MyEntity")]
public class MyEntity
{
[Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public Guid Id { get; set; }
public string MyColumn { get; set; }
public int MyNumber { get; set; }
}
[Table("MySecondEntity")]
public class MySecondEntity
{
[Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public Guid Id { get; set; }
public string MyColumn { get; set; }
public int MyNumber { get; set; }
}
public class MyContext : DbContext
{
public DbSet<MyEntity> MyTable { get; set; }
public DbSet<MySecondEntity> MyTable2 { get; set; }
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
var connectionStringBuilder = new SqliteConnectionStringBuilder {DataSource = "test.db"};
var connectionString = connectionStringBuilder.ToString();
var connection = new SqliteConnection(connectionString);
optionsBuilder.UseSqlite(connection);
}
}
在我看来它应该可以工作,但是当我在下面的代码中调用它时,它会在遇到第一个 foreach 循环时出现“没有这样的表:MyEntity”Sqlite 异常。
static void Main(string[] args)
{
using (var db = new MyContext())
{
MyEntity testEntity1 = new MyEntity();
MySecondEntity entity1 = new MySecondEntity();
testEntity1.MyColumn = "Test Data 1";
testEntity1.MyNumber = 12345;
db.MyTable.Add(testEntity1);
db.Database.Migrate();
entity1.MyColumn = "New Data 1";
entity1.MyNumber = 2;
db.MyTable2.Add(entity1);
db.Database.Migrate();
Console.WriteLine("Inserting Data...");
Console.WriteLine("Data in the Database");
foreach (var entity in db.MyTable)
{
Console.WriteLine("Id: " + entity.Id);
Console.WriteLine("Column Data: " + entity.MyColumn);
Console.WriteLine("Number: " + entity.MyNumber);
}
foreach (var entity in db.MyTable2)
{
Console.WriteLine("Id: " + entity.Id);
Console.WriteLine("Column Data: " + entity.MyColumn);
Console.WriteLine("Number: " + entity.MyNumber);
}
}
Console.WriteLine("Examples run finished,press Enter to continue...");
Console.ReadLine();
}
我几乎可以保证这是我错过的一些简单的东西,但我似乎找不到它,而且我在他们的文档中找不到任何示例。 GitHub上似乎有一个类似的问题提交在这里https://github.com/aspnet/EntityFramework/issues/2874 https://github.com/aspnet/EntityFramework/issues/2874但这是针对多个上下文的。那么也许这是另一部尚未发布的作品?
Solution
按照发布的教程进行操作http://ef.readthedocs.org/en/latest/getting-started/uwp.html http://ef.readthedocs.org/en/latest/getting-started/uwp.html根据@natemcmaster的建议和@lukas-kabrt推荐的解决方案,我能够让它按需要工作。通过运行以下命令,我能够创建创建的表并从中插入/选择数据。
Install-Package EntityFramework.Commands –Pre
Add-Migration MyFirstMigration
Update-Database