LinqToXml;查询属性不存在的位置

Question

是否存在属性不存在的语法？

    Dim xe As XElement = _
    <xml>
        <el att1="ABC" att2="XYZ"/>
        <el att1="ABC"/>
        <el/>
    </xml>

    Dim xe2 As IEnumerable(Of XElement)
    xe2 = From c In xe.<el> Where c.@att1 = "ABC" And DoesNotExist(c.@att2)

    'Return: <el att1="ABC"/>

Answer 1

xe2 = From c In xe.<el> Where c.@att1 = "ABC" And c.@att2 Is Nothing

Answer 2

试试String.IsNullOrEmpty(c.@att2)。