Question

我正在尝试使用datagridview组合框制作一个选项列表，该列表正确显示但在选择它时会给出类型/转换错误。它给出字符串，但期望实体类型MyProduct。

错误从System.String转换为MyProduct无效

   private void frmtest_Load(object sender, EventArgs e)
    {
        var products = new BindingList<MyProduct>()
        {
        new MyProduct(){ID =1,Name="Product1"       },
        new MyProduct(){ID =2,Name="Product2"       },
        new MyProduct(){ID =4,Name="Product3"       },
        new MyProduct(){ID =5,Name="Product4"       }

        };
        MyProduct.DataSource= products;//comboboxcolumn datasource

    }


public class MyProduct
{
    public MyProduct()
    {

    }
    public int ID { get; set; }
    public string Name { get; set; }
    public string Specification { get; set; }
    public override string ToString()
    {
        return Name;
    }
}
public class MyPurchaseItem
{
    public MyPurchaseItem()
    {

    }
    public int ID { get; set; }
    public virtual MyProduct MyProduct { get; set; }
    public int qty { get; set; }
    public decimal Price { get; set; }
}

Answer 1

阅读各种回复后，设法通过添加返回同一对象的方法来解决此问题。

这需要一个nethod来返回可以分配给ValueMember的对象本身，然后设置displaymember。

public MyProduct()
    {

    }
    public int ID { get; set; }
    public string Name { get; set; }
    public string Specification { get; set; }
    ***public MyProduct Self { get { return this; }  }***
    public override string ToString()
    {
        return Name;
    }

//datagridcombobox changed as below
        MyProduct.DataPropertyName = "MyProduct";
        MyProduct.ValueMember = "Self";
        MyProduct.DisplayMember = "Name";

Winform datagridview组合框EF映射错误

1 个答案: