C# 由属性组成的下拉列表 DataTextField？
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dropdownlist DataTextField composed from properties?
提问by karlis
is there a way to make the datatextfield property of a dropdownlist in asp.net via c# composed of more than one property of an object?
有没有一种方法可以通过由一个对象的多个属性组成的 c# 使 asp.net 中的下拉列表的 datatextfield 属性？
public class MyObject
{
public int Id { get; set; }
public string Name { get; set; }
public string FunkyValue { get; set; }
public int Zip { get; set; }
}
protected void Page_Load(object sender, EventArgs e)
{
List<MyObject> myList = getObjects();
ddList.DataSource = myList;
ddList.DataValueField = "Id";
ddList.DataTextField = "Name";
ddList.DataBind();
}
I want e.g. not use "Name", but "Name (Zip)" eg.
我想要例如不使用“名称”，而是“名称（邮编）”例如。
Sure, i can change the MyObject Class, but i don't want to do this (because the MyObject Class is in a model class and should not do something what i need in the UI).
当然，我可以更改 MyObject 类，但我不想这样做（因为 MyObject 类位于模型类中，不应在 UI 中执行我需要的操作）。
采纳答案by M4N
Add another property to the MyObject class and bind to that property :
将另一个属性添加到 MyObject 类并绑定到该属性：
public string DisplayValue
{
get { return string.Format("{0} ({1})", Name, Zip); }
}
Or if you can not modify MyObject, create a wrapper object in the presentation layer (just for displaying). This can also be done using some LINQ:
或者如果不能修改MyObject，则在表现层创建一个包装对象（仅用于显示）。这也可以使用一些 LINQ 来完成：
List<MyObject> myList = getObjects();
ddList.DataSource = (from obj in myList
select new
{
Id = obj.Id,
Name = string.Format("{0} ({1})", obj.Name, obj.Zip)
}).ToList();
ddList.DataValueField = "Id";
ddList.DataTextField = "Name";
ddList.DataBind();
(sorry I don't have Visual Studio available, so there might be errors in the code)
（对不起，我没有可用的 Visual Studio，所以代码中可能有错误）
回答by ecoffey
I would recommend reading this: http://martinfowler.com/eaaDev/PresentationModel.html
我建议阅读：http: //martinfowler.com/eaaDev/PresentationModel.html
Essentially you want to create a class that represents binding to a particular UI. So you would map your Model (My Object in your example) to a ViewModel object, and then bind the drop down list that way. It's a cool way to think about separation of concerns.
本质上，您希望创建一个表示绑定到特定 UI 的类。因此，您可以将您的模型（在您的示例中为我的对象）映射到一个 ViewModel 对象，然后以这种方式绑定下拉列表。这是考虑关注点分离的一种很酷的方式。
EDIT: Here is another blog series on ViewModel: http://blogs.msdn.com/dancre/archive/2006/10/11/datamodel-view-viewmodel-pattern-series.aspx
编辑：这是关于 ViewModel 的另一个博客系列：http: //blogs.msdn.com/dancre/archive/2006/10/11/datamodel-view-viewmodel-pattern-series.aspx
回答by Achilles
BTW, Try assigning the "DataTextField" and "DataValueField" before you assign the DataSource. Doing so will prevent firing the "SelectedIndexChanged" event while databinding...
顺便说一句，在分配数据源之前尝试分配“DataTextField”和“DataValueField”。这样做将防止在数据绑定时触发“SelectedIndexChanged”事件...
