VB没有实现集合

Question

我在我的 VB ASP.Net 项目中使用 linq 来填充搜索结果。使用 intersect 比较作为查询的单词列表和字符串。我在空格上拆分字符串以确保两个集合相交。但 VB 并没有意识到这一点并抛出以下错误。

An exception of type 'System.MissingMemberException' occurred in Microsoft.VisualBasic.dll but was not handled in user code

Additional information: Public member 'Count' on type 'String' not found.

select 语句中出现的代码如下

MatchCount = keywords.Intersect(IIf(IsNothing(t.TripName), t.tbl_Subject.SubjectName & " in " & t.tbl_City.CityName, t.TripName).ToLower().Split(" ")).Count() / IIf(IsNothing(t.TripName), t.tbl_Subject.SubjectName & " in " & t.tbl_City.CityName, t.TripName).Count

为它难以阅读的性质道歉，它在一个选择语句中，所以必须是一个查询。跨多行拆分它看起来像这样：

Dim name as string = IIf(IsNothing(t.TripName), t.tbl_Subject.SubjectName & " in " & t.tbl_City.CityName, t.TripName)
MatchCount = keywords.Intersect(name.ToLower().Split(" ")).Count()

编辑：- 完整的、原始的（不是我写的）选择语句

toReturn.AddRange(results.Select(Function(t) New SearchResult() _
                      With {
                            .MatchCount = keywords.Intersect(If(IsNothing(t.TripName), t.tbl_Subject.SubjectName & " in " & t.tbl_City.CityName, t.TripName).ToLower().Split(" ")).Count() / If(IsNothing(t.TripName), t.tbl_Subject.SubjectName & " in " & t.tbl_City.CityName, t.TripName).Count, _
                            .UID = t.TripID, _
                            .Title = IIf(t.TripName Is Nothing, t.tbl_Subject.SubjectName & " in " & t.tbl_City.CityName, t.TripName), _
                            .Description = t.DescriptionLong.ToString().Replace("<p>", "").Replace("</p>", "").Replace("<b>", "").Replace("</b>", "").Replace("<strong>", "").Replace("</strong>", "").Replace("<i>", "").Replace("</i>", "").Replace("<em>", "").Replace("</em>", "").Replace("<br>", "").Replace("<br />", ""), _
                            .ImageURL = IIf(t.ImageSub04 Is Nothing, t.tbl_City.ImageThumb, t.ImageSub04),
                            .URL = "/" & t.tbl_Subject.SubjectWebName & "/" & t.tbl_Country.CountryWebName & "/" & _
                                        IIf(t.TripWebName Is Nothing, _
                                        t.tbl_City.CityWebName, _
                                        t.TripWebName) _
                                        & "_trip/",
                            .IsCity = keywords.Contains(t.tbl_City.CityName) Or keywords.Contains(t.tbl_Country.CountryName)
                         }).OrderBy(Function(sr) sr.IsCity).ThenByDescending(Function(sr) sr.MatchCount))

Answer 1

既然您也在字符串上使用Count()，为什么不在那里使用Length？

因为，正如我在问题中所说，它在一个选择语句中，所以我不能 存储变量

您甚至可以在查询中，例如使用匿名类型或（在查询语法中）使用 Let 关键字。

在这种情况下，我猜这就是你想要做的，看看它的可读性如何：

Dim sResults = From res In results
               Let longTripName = String.Format("{0} in {1}", res.tbl_Subject.SubjectName, res.TripName)
               Let trip = If(res.TripName, longTripName)
               Let tripWords = trip.ToLower().Split(" "c)
               Let matching = keywords.Intersect(tripWords).Count()
               Let matchCount = matching / trip.Length
               Let title = " this is your task "
               Let description = " this is your task "
               Let imageURL = " this is your task "
               Let url = " this is your task "
               Let isCity = True ' also your task '
               Select sr = New SearchResult With {
                   .MatchCount = matchCount,
                   .Title = title,
                   .Description = description,
                   .ImageURL = imageURL,
                   .URL = url,
                   .IsCity = isCity
               }
               Order By sr.IsCity, sr.MatchCount Descending
toReturn.AddRange(sResults)

但总的来说，我建议在 SearchResult 中实现一个适当的方法或构造函数，它封装了逻辑和复杂性。

此外，由于您使用的是 Split(" ") 并且可以编译，因此您应该真正更改为 Option Strict On。我猜你会得到很多编译器错误，这是一件好事，因为它向你展示了你必须解决的问题。在这里你必须使用Split(" "c)。