Dynamic LINQ

Question

hi all,

i want to write a dynamic linq like this in C#

but, my doubt is, how do i write left outer join like above example(using dynamic LINQ).?

experts pleasse guide me.

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Thanks In Advance, Jeyaseelan

Answer 1

experts please guide me.

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Thanks In Advance, Jeyaseelan

Answer 2

Hi jeyaseelan2,

left outer join in LINQ is done with the help of DefaultIfEmpty() method. It will be better if you use sql version of LINQ insteed of methodised version as you have done, something like this :

Dim query = From el in Products _
            Join t in xyz on el equals t.SomeField into gj_
            From t1 in gj.DefaultIfEmpty()
            Where el.CategoryID=2 And UnitPrice>3 _
            Select New ....
           

Please folow this link where left outer join in LINQ has been explained.Though it is in C# it will not matter to convert to VB.NET.

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One good question is equivalent to ten best answers.

Answer 3

Hi Jeyaseelan,

You can use Enumerable.GroupJoin method: http://msdn.microsoft.com/en-us/library/vstudio/bb534297.aspx

There is a simple example on previous link.

Good day.

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Alexander Sun [MSFT]
MSDN Community Support | Feedback to us
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Answer 4

thanks for your reply but, my situation is i dont know what are all the columns will come for where clause so, as per the example i cant hardcode the column names.

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Thanks In Advance, Jeyaseelan

Answer 5

I also wanted left join solution with DLINQ but couldn't find it. However I can suggest you general LINQ  LEFT JOIN solution from my blog post.

http://msguy.net/post/2013/01/04/LINQ-Join-Operations.aspx#left-join

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Also please visit my blog http://msguy.net/

Answer 6

thanks for your interest michel but, i want it in DLINQ

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Thanks In Advance, Jeyaseelan

Answer 7

Hi Jeyaseelan,

I don’t understand. Do you mean you don’t know column names and don’t know how to use column names in groupjoin?

Good day.

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Alexander Sun [MSFT]
MSDN Community Support | Feedback to us
Develop and promote your apps in Windows Store
Please remember to mark the replies as answers if they help and unmark them if they provide no help.

Answer 8

thanks for your reply but, my situation is i dont know what are all the columns will come for where clause so, as per the example i cant hardcode the column names.

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Thanks In Advance, Jeyaseelan

In your first posted example, you know what the columns are. They are all column from table products that match the criteria in the where clause. So, You don't need to hardcode the columns..

btw.. you begin with an example that has no relation with your questions.. What do you want exactly?

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