Question

如何融合这两个If语句以使我的Droplist过滤器协同工作以过滤数据？我有2个droplists（transfilter和Soortfilter），我希望能够从droplist 1中选择一些东西并从droplist 2中选择其他东西，然后按filter并让它显示通过过滤选择的项目两个过滤器。

@此时我返回View(query.ToList())只显示Droplist 1中的过滤条目

Function Index(transFilter As TransactieType?, soortfilter As Soort?) As ActionResult
            Dim query As IEnumerable(Of Pand)
            If Not transFilter.HasValue OrElse transFilter.Value = TransactieType.Beiden Then
                query = db.Panden
            Else
                query = db.Panden.Where(Function(p) p.TransactieType = transFilter.Value)

            End If
            If Not soortfilter.HasValue OrElse soortfilter.Value = Soort.All Then
                query = db.Panden
            Else
                query = db.Panden.Where(Function(p) p.Soort = soortfilter.Value)

            End If
            Return View(query.ToList())
        End Function

我正在尝试这个，但这并没有真正起作用

Function Index(transFilter As TransactieType?, soortfilter As Soort?) As ActionResult
    Dim query As IEnumerable(Of Pand)
    If Not transFilter.HasValue And soortfilter.HasValue OrElse transFilter.Value = TransactieType.Beiden And soortfilter.Value = Soort.All Then
        query = db.Panden
    Else
        query = db.Panden.Where(Function(p) p.TransactieType = transFilter.Value And p.Soort = soortfilter.Value)

    End If

    Return View(query.ToList())

Answer 1

问题是您在query = db.Panden个语句的第一部分设置了If。当您处理逐步构建LINQ查询时，始终

从基础案例开始。在这种情况下，它将是Dim query As IEnumerable(Of Pand)

使用query = query.Where将每个额外的过滤器直接添加到该基本案例。

Function Index(transFilter As TransactieType?, soortfilter As Soort?) As ActionResult
    Dim query As IEnumerable(Of Pand) = db.Panden
    If transFilter.HasValue AndAlso transFilter.Value <> TransactieType.Beiden Then
        query = query.Where(Function(p) p.TransactieType = transFilter.Value)
    End If

    If soortfilter.HasValue AndAlso soortfilter.Value <> Soort.All Then
        query = query.Where(Function(p) p.Soort = soortfilter.Value)
    End If

    Return View(query.ToList())
End Function

如何将两个条件过滤器添加到同一个IEnumerable中？

1 个答案: