entity framework - DbScanExpression with join and left table select -

colleagues.

i have group of classes(tables) have common properties(columns). using entityframework intercept select queries , modify them.

i add join , clauses. don't know how project left table without explicit properties selection.

initial query this: context.loans

sql

select      [loannumber] [loannumber],      [sec_owner] [sec_owner] [dbo].[loans] 

should modified following:

select      o.loannumber loannumber,      o.sec_owner sec_owner,    dbo.loans o left outer join dbo.users u     on          o.sec_owner = u.sec_id          ,         u.name = n'root'          ((256 = (o.sec_permissions & 256))          ,          (o.sec_owner = u.sec_id))   var joinexpression = expression.leftouterjoin(                 userentitybase.scan(),                 (l, r) =>                     l.property("sec_owner").equal(r.property("sec_id"))                     .and(r.property("name").equal(dbexpression.fromstring(this.username)))                 )                 .where(                     exp =>                         dbexpressionbuilder                             .constant((int)accesspermissions.ownerread).equal(exp.property("l").property("sec_permissions").bitwiseand(dbexpressionbuilder.constant((int)accesspermissions.ownerread)))                             .and(exp.property("l").property("sec_owner").equal(exp.property("r").property("sec_id")))             ); 

as understand join projects columns both table. need project initial select without knowing it.

select      [loannumber] [loannumber],      [sec_owner] [sec_owner] 

thanks in advance,

/artem

as work around issue removed join query , decided use subselects.

public override dbexpression visit(dbscanexpression expression) { 

...

                var userentitybase = expression.target.entitycontainer.getentitysetbyname("user", true);                  var newexpression = expression                     .where(                         exp =>                             ...                                 .and(exp.property("sec_owner")                                     .equal(userentitybase.scan().where(user => user.property("name").equal(dbexpression.fromstring(username))).select(u => u.property("sec_id")).take(1).element())                                 )                             )                             ...                 );                  ...              return base.visit(expression);         } 

.select(u => u.property("sec_id")).take(1).element() evaluates select top 1