Question

我使用DB第一种方法

我有3个表，其中包含“订单”列（客户订单记录）。我想创建类似的逻辑来重新排序我的.NET应用程序，所以，我想使用基类。我创建了以下结构：

但是项目无法编译，没有为每个3个表映射列Order，我看不到映射它的方法：

怎么说，Order列应该映射到父类的Order属性？

更新：

否则我必须创建类似的方法：

public interface IOrder
{
    int Order { get; set; }
}

public partial class EscortDescription : IOrder
{
}

public partial class EscortGroup : IOrder
{

}

public partial class EscortItem : IOrder
{

}

    private async Task ReorderEscortAsync(Infrastructure.IOrder item1, Infrastructure.IOrder item2)
    {
        Random rnd = new Random();
        if (item1 == null)
            throw new ArgumentNullException("firstItem");

        if (item2 == null)
            throw new ArgumentNullException("secondItem");

        int tmpItem1Order = item1.Order;
        int tmpItem2Order = item2.Order;
        item1.Order = rnd.Next(int.MinValue, -1);
        item2.Order = rnd.Next(int.MinValue, -1);
        _db.SaveChanges();

        item1.Order = tmpItem2Order;
        item2.Order = tmpItem1Order;
        await _db.SaveChangesAsync();
    }

    public async Task EscortGroupItemUpAsync(int ItemID)
    {
        var firstItem = (from i in _db.EscortItems where i.ID == ItemID select i).FirstOrDefault();
        if (firstItem == null)
            throw new Domain.RecordNotFoundException<int>(ItemID, "ID", "EscortItems");
        var secondItem = (from i in _db.EscortItems where i.Order < firstItem.Order orderby i.Order descending select i).FirstOrDefault();

        if (secondItem != null)
            await ReorderEscortAsync(firstItem, secondItem);
        else
            throw new FirstRecordException();
    }

    public async Task EscortGroupItemDownAsync(int ItemID)
    {
        var secondItem = (from i in _db.EscortItems where i.ID == ItemID select i).FirstOrDefault();
        if (secondItem == null)
            throw new Domain.RecordNotFoundException<int>(ItemID, "ID", "EscortItems");
        var firstItem = (from i in _db.EscortItems where i.Order > secondItem.Order orderby i.Order ascending select i).FirstOrDefault();

        if (firstItem != null)
            await ReorderEscortAsync(firstItem, secondItem);
        else
            throw new LastRecordException();
    }

    public async Task EscortGroupUpAsync(int ItemID)
    {
        var firstItem = (from i in _db.EscortGroups where i.ID == ItemID select i).FirstOrDefault();
        if (firstItem == null)
            throw new Domain.RecordNotFoundException<int>(ItemID, "ID", "EscortGroups");
        var secondItem = (from i in _db.EscortGroups where i.Order < firstItem.Order orderby i.Order descending select i).FirstOrDefault();

        if (secondItem != null)
            await ReorderEscortAsync(firstItem, secondItem);
        else
            throw new FirstRecordException();
    }

    public async Task EscortGroupDownAsync(int ItemID)
    {
        var secondItem = (from i in _db.EscortGroups where i.ID == ItemID select i).FirstOrDefault();
        if (secondItem == null)
            throw new Domain.RecordNotFoundException<int>(ItemID, "ID", "EscortGroups");
        var firstItem = (from i in _db.EscortGroups where i.Order > secondItem.Order orderby i.Order ascending select i).FirstOrDefault();

        if (firstItem != null)
            await ReorderEscortAsync(firstItem, secondItem);
        else
            throw new LastRecordException();
    }

我想有一个方法并将基类的对象作为参数传递

Answer 1

如果我理解你，OrderBase没有表格。这意味着这是一个每个具体的表格（TPC）映射。 This link表明，在代码优先的情况下，映射TPC并不难。

数据库优先和TPC不能一起玩得很好。您必须编辑EDMX才能完成此操作。

我用你的两个课做了。目前，在您的EDMX的CS映射内容部分中，您将找到如下内容：

  <EntitySetMapping Name="OrderBases">
    <EntityTypeMapping TypeName="IsTypeOf(TPCModel.EcortGroup)">
      <MappingFragment StoreEntitySet="EcortGroup">
        <ScalarProperty Name="GroupName" ColumnName="GroupName" />
        <ScalarProperty Name="ID" ColumnName="ID" />
      </MappingFragment>
    </EntityTypeMapping>
    <EntityTypeMapping TypeName="IsTypeOf(TPCModel.EscortItem)">
      <MappingFragment StoreEntitySet="EscortItem">
        <ScalarProperty Name="Escort" ColumnName="Escort" />
        <ScalarProperty Name="EcortGroup_ID" ColumnName="EcortGroup_ID" />
        <ScalarProperty Name="ID" ColumnName="ID" />
      </MappingFragment>
    </EntityTypeMapping>
  </EntitySetMapping>

这告诉哪些列映射到哪些属性。如您所见，Order丢失了。但你可以手动添加它们，EF会很高兴，EDMX仍然可以在设计师中打开：

    <EntityTypeMapping TypeName="IsTypeOf(TPCModel.EcortGroup)">
      <MappingFragment StoreEntitySet="EcortGroup">
        <ScalarProperty Name="GroupName" ColumnName="GroupName" />
        <ScalarProperty Name="ID" ColumnName="ID" />
        <ScalarProperty Name="Order" ColumnName="Order" />
      </MappingFragment>
    </EntityTypeMapping>
    <EntityTypeMapping TypeName="IsTypeOf(TPCModel.EscortItem)">
      <MappingFragment StoreEntitySet="EscortItem">
        <ScalarProperty Name="Escort" ColumnName="Escort" />
        <ScalarProperty Name="EcortGroup_ID" ColumnName="EcortGroup_ID" />
        <ScalarProperty Name="ID" ColumnName="ID" />
        <ScalarProperty Name="Order" ColumnName="Order" />
      </MappingFragment>
    </EntityTypeMapping>

HOWEVER ：从数据库更新模型时，修改将会消失。每次执行此操作时，您都必须再次添加它们。如果可以，我强烈建议您将代码移植到代码优先。

实体框架和继承

1 个答案: