我有3个具有相同来源的下拉列表2,第3个具有所选列表。如果选择列表不为null,我应该从第一个中删除选定项,并在第三个中绑定。第二个是静态的,显示原始列表。
但是我无法弄清楚如何在一个物体中前进。
错误:foreach语句无法对'object'类型的变量进行操作 因为'object'不包含公共定义 '的GetEnumerator'
public void DataSource(object source, object select, string Value = "UId", string Text = "Text")
{
ddlThis.DataSource = source;
ddlThis.DataTextField = Text;
ddlThis.DataValueField = Value;
ddlThis.DataBind();
ddlThisHidden.DataSource = source;
ddlThisHidden.DataTextField = Text;
ddlThisHidden.DataValueField = Value;
ddlThisHidden.DataBind();
if (select != null)
{
ddlOther.DataSource = select;
ddlOther.DataTextField = Text;
ddlOther.DataValueField = Value;
ddlOther.DataBind();
foreach (var item in ddlOther.DataSource)
ddlThis.Items.Remove(item);
}
}
版本2
public void DataSource(IList source, IList select, string Value = "UId", string Text = "Text")
{
ddlThis.DataSource = source;
ddlThis.DataTextField = Text;
ddlThis.DataValueField = Value;
ddlThis.DataBind();
ddlThisHidden.DataSource = source;
ddlThisHidden.DataTextField = Text;
ddlThisHidden.DataValueField = Value;
ddlThisHidden.DataBind();
if (select != null)
{
ddlOther.DataSource = source.Cast<object>()
.Select(x => select.Cast<object>().Any(c=> c.GetType().GetProperty(Value).GetValue(source, null).ToString() == x.GetType().GetProperty(Value).GetValue(source, null).ToString()));
ddlOther.DataTextField = Text;
ddlOther.DataValueField = Value;
ddlOther.DataBind();
foreach (var item in select)
ddlThis.Items.Remove(item.ToString());
}
}
版本3 工作!
public void DataSource(object source, object select, string Value = "UId", string Text = "Text")
{
ddlThis.DataSource = source;
ddlThis.DataTextField = Text;
ddlThis.DataValueField = Value;
ddlThis.DataBind();
ddlThisHidden.DataSource = source;
ddlThisHidden.DataTextField = Text;
ddlThisHidden.DataValueField = Value;
ddlThisHidden.DataBind();
if (select != null)
{
ddlOther.DataSource = ((IEnumerable)source).Cast<dynamic>().ToList().FindAll(x => ((IEnumerable)select).Cast<dynamic>()
.Any(c => c.GetType().GetProperty(Value).GetValue(c, null) == x.GetType().GetProperty(Value).GetValue(x, null)));
ddlOther.DataTextField = Text;
ddlOther.DataValueField = Value;
ddlOther.DataBind();
foreach (var item in (dynamic)(ddlOther.DataSource))
ddlThis.Items.Remove(item.ToString());
}
}
答案 0 :(得分:19)
如果您不知道对象的确切类型,但您确定无论它是什么,它都会有GetEnumerator
(例如,因为它是一个集合或您自己的一个对象实现IEnumerable
)你可以通过强制转换为dynamic
来阻止编译器发出错误,如下所示:
foreach (var item in (dynamic)(ddlOther.DataSource)) {
...
}
这里的交易是,如果事实证明ddlOther.DataSource
没有GetEnumerator
,则会在运行时收到错误,而不是编译时错误。
答案 1 :(得分:0)
修改代码以检查IEnumerable接口。它有根深蒂固的感觉更多你想要的东西。
public void DataSource(object source, object select, string Value = "UId", string Text = "Text")
{
ddlThis.DataSource = source;
ddlThis.DataTextField = Text;
ddlThis.DataValueField = Value;
ddlThis.DataBind();
ddlThisHidden.DataSource = source;
ddlThisHidden.DataTextField = Text;
ddlThisHidden.DataValueField = Value;
ddlThisHidden.DataBind();
if (select != null)
{
ddlOther.DataSource = select;
ddlOther.DataTextField = Text;
ddlOther.DataValueField = Value;
ddlOther.DataBind();
if (select is IEnumerable) //check if the object is a list of objects
foreach (var item in (IEnumerable)ddlOther.DataSource)
ddlThis.Items.Remove(item);
else //try to remove the single object
ddlThis.Items.Remove(select)
}
}