SamoBellows SamoBellows - 3 years ago 183
Vb.net Question

LINQ to XML, get unique node in VB.NET

I have an XML file that represents a list of books that the user has access to.

<Book Bookid="1" BookName="Book1" />
<Book Bookid="1" BookName="Book1" />
<Book Bookid="2" BookName="Book2" />
<Book Bookid="1" BookName="Book1" />


That is in an XElement named xBooks

I am trying to get each book in the XML once.

Dim DistinctBooks = (From item In xBooks.Elements("Book") Select item).Distinct()


That line doesn't seem to do anything, the value of DistinctBooks is the same as xBooks.

I have searched for the solution, but it seems everyone that is doing LINQ is doing it in C#. Even though i've found other posts in C# that should work, i'm either not translating from C# to VB correctly, or VB does things differently. can anyone bump me in the right direction to get this to work in VB?

Thanks!

Sam

Answer Source

Assuming this is declared:

Dim xBooks = <books>
               <Book Bookid="1" BookName="Book1"/>
               <Book Bookid="1" BookName="Book1"/>
               <Book Bookid="2" BookName="Book2"/>
               <Book Bookid="1" BookName="Book1"/>
             </books>

I think you are looking for something like this:

Dim DistinctBooks = From item In xBooks.Elements("Book")
                    Select bookid = item.Attribute("Bookid").Value,
                           bookName = item.Attribute("BookName").Value
                    Distinct

Why it did not work for you is because every node is different if you consider a set of all properties that it implements. With the above you tell it which properties you need as part of a unique key for distinct. Also notice there is no need to combine multiple styles of LINQ (query and functional), you can use word Distinct as part of the query.

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