How to build join string by expression tree

Question

all

Below is my query code:

var users = db.users.where(u=> u.id=5 && db.usergroups.any(d=>d.user_id=u.id))

Build the expression tree for the condition u.id=5 is easy, but who can tell me how to build the condition db.usergroups.any(d=>d.user_id=u.id)

thanks

The code looks fine. What is the problem? Do you mean to build the expression tree by hand? — Jean Hominal
– Jean Hominal, Commented Apr 5, 2014 at 10:09
I mean, with calls to the static methods of the Expression class? — Jean Hominal
– Jean Hominal, Commented Apr 5, 2014 at 10:10
This code is static, I just want to convert it to dynamic query — user2155362
– user2155362, Commented Apr 5, 2014 at 10:21

Jean Hominal · Accepted Answer · 2014-04-05 11:11:32Z

1

The simplest way to obtain the expression created by the C# compiler is to affect it to a variable of the correct type, and looking at it in a debugger; in your case:

Expression<Func<User, bool>> lambdaExpression =
    u => u.id == 5 && db.UserGroups.Any(d => d.user_id == u.id);

And then look at the lambdaExpression variable in a debugger.

answered Apr 5, 2014 at 11:11

Jean Hominal

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