真是令人尴尬的问题——我有 Subsonic 集合，然后我使用 Where 过滤掉一些数据。
MyColl.Where(it => it.foo()==true)
现在我想将这些数据仍然作为 Subsonic 集合传递。怎么做（最正确的方法）？我检查了 Subsonic 集合、ToX() 方法的构造函数，并用谷歌搜索。
编辑：Subsonic 2.x 系列。
提前感谢您，对于幼稚的问题，我们深表歉意。
【问题讨论】：
标签： linq subsonic ienumerable collections
在 SubSonic 2.x 中，数据实际上并没有被 Where() 过滤掉，直到对数据库重新执行查询。我假设这在 3.0 中是相同的。在 2.x 中有一个 .Filter() 方法可以满足您的需求。
.Filter() 方法被添加到生成的类中。这是我的样子（它是默认定制的）：
/// <summary>
/// Filters an existing collection based on the set criteria. This is an in-memory filter.
/// All existing wheres are retained.
/// </summary>
/// <returns>TblSomethingOrOtherCollection</returns>
public TblSomethingOrOtherCollection Filter(SubSonic.Where w)
{
return Filter(w, false);
}
/// <summary>
/// Filters an existing collection based on the set criteria. This is an in-memory filter.
/// Existing wheres can be cleared if not needed.
/// </summary>
/// <returns>TblSomethingOrOtherCollection</returns>
public TblSomethingOrOtherCollection Filter(SubSonic.Where w, bool clearWheres)
{
if (clearWheres)
{
this.wheres.Clear();
}
this.wheres.Add(w);
return Filter();
}
/// <summary>
/// Filters an existing collection based on the set criteria. This is an in-memory filter.
/// Thanks to developingchris for this!
/// </summary>
/// <returns>TblSomethingOrOtherCollection</returns>
public TblSomethingOrOtherCollection Filter()
{
for (int i = this.Count - 1; i > -1; i--)
{
TblSomethingOrOther o = this[i];
foreach (SubSonic.Where w in this.wheres)
{
bool remove = false;
System.Reflection.PropertyInfo pi = o.GetType().GetProperty(w.ColumnName);
if (pi != null && pi.CanRead)
{
object val = pi.GetValue(o, null);
if (w.ParameterValue is Array)
{
Array paramValues = (Array)w.ParameterValue;
foreach (object arrayVal in paramValues)
{
remove = !Utility.IsMatch(w.Comparison, val, arrayVal);
if (remove)
break;
}
}
else
{
remove = !Utility.IsMatch(w.Comparison, val, w.ParameterValue);
}
}
if (remove)
{
this.Remove(o);
break;
}
}
}
return this;
}
}
【讨论】：
由于某种原因，我永远无法让过滤器的内联方法工作，但它易于使用，如下所示：
SubSonic.Where w = new Where();
w.ColumnName = Product.CatIDColumn.PropertyName;
w.Comparison = Comparison.Equals;
w.ParameterValue = "1";
ProductCollection objFilteredCol = objProdCollection.Where(w).Filter();
【讨论】：