在列表中搜索對象

Question

我有一個對象列表，我想搜索它以查看myobject.articleID是否與給定的articleID匹配。從我收集的使用.Find（的T）是這個最好的方式，但我有一些困難實施它。這裏有一些我到目前爲止的代碼：

<WebMethod()> _ 
Public Function SetTagOnFavorite(ByVal articleID As Integer, ByVal tagtext As String, ByVal mobileGUID As String) As AddTagResult 
    Dim result As New AddTagResult 
    Dim userID As Long = GetUserIDByMobileGUID(mobileGUID) 


    If userID > 0 Then 
     Dim pageNum As Integer = 1 
     Dim pageLen As Integer = 500 'arbitrarily large number 
     Dim savedArticleList As New List(Of SimpleArticle) 
     savedArticleList = GetSavedArticles(mobileGUID, pageNum, pageLen) 

     If savedArticleList.Find(Function(m As SimpleArticle) m.articleID = articleID) 


      Dim lq As New lqDFDataContext 
      Dim var = lq.web_AddTagToArticle(userID, articleID, tagtext).ToList() 

      If var.Any() Then 
       Dim vRes = var.First() 
       result.articletagID = vRes.articletagID 
       result.newarticletag = vRes.newarticletag 
       result.newusertag = vRes.newusertag 
       result.usertagID = vRes.usertagID 
       result.resultinfo = "Success." 

      End If 
     End If 
    Else 
     result.resultinfo = STR_NoUserIDMostLikelyTheSessionTimedOut 
    End If 
    Return result 
End Function 

我得到的錯誤是，「SimpleArticle類型的值不能轉換爲布爾值」。

Answer 1

因爲Find(Of返回找到的對象，您需要更改這一行：

If savedArticleList.Find(Function(m As SimpleArticle) m.articleID = articleID) 

到

If savedArticleList.Find(Function(m As SimpleArticle) m.articleID = articleID) IsNot Nothing 

，或者如果你需要找到的項目中，Find結果存儲在一個局部變量。

Answer 2

你可以進一步優化@ competent_tech的答案：

If savedArticleList.Any(Function(m) m.articleID = articleID))