WCF returning wrong view output - wcf

Question

Here I struck in some strange situation.
I created a view in SQL Server
Create View [Adm].[VwSurveyReport]
as
SELECT q.QuestionID,q.Question,p.dtStart,p.dtEnd,u.OrgCode,u.UserID,u.RoleID,
(case tc.blanswer
when 1 then 1
when 0 then 0
end) as AnsYes,
(case tc.blanswer
when 1 then 0
when 0 then 1
end) as AnsNo
from dbo.SurveyQuestions as q
left outer join dbo.surveyTransChild as tc on tc.questionID=q.questionID
left outer join dbo.surveyTransParent as tp on tp.SurveyTransID=tc.SurveyTransID
left outer join dbo.SurveyParent as p on p.surveyID=tp.surveyID
left outer join adm.masFEUser as u on tp.Userid=u.Userid
where p.dtStart IS Not NULL
GO
and my code behind is
List<ThePayWcfRef.VwSurveyReport> data = new List<ThePayWcfRef.VwSurveyReport>();
data = (from v in entities.VwSurveyReports
where 1 == 1
select v).ToList();
When I run select query in SQL Server it is showing exact output which I want
UserID RoleID AnsYes AnsNo
m6018upl 2 1 0
m6018upl 2 1 0
m6018app1 4 1 0
m6018app1 4 0 1
but in my code behind I am getting wrong data into "data" list
UserID RoleID AnsYes AnsNo
m6018app1 4 1 0
m6018app1 4 0 1
m6018app1 4 1 0
m6018app1 4 0 1
AnsYes, AnsNo and UserID are wrong
Please help me.
Thanks in advance.

Answer 1

I don't know what your EF model looks like - but the issue with views in Entity Framework often boils down to this:
since a view by default doesn't have a primary key, EF will "infer" an "entity key" based on all the columns in the view that are guaranteed to be NOT NULL
those columns might (or might not) make a good surrogate primary key
when EF loads the data, it will look at those columns in the primary key; if an entity with that same EntityKey has already been loaded from the database, EF will not load the data again, but reference that entity it already has in memory
All this together can lead to unexpected results on EF using views.
There are a number of solutions around this:
make sure to include all primary keys from all included base tables in your view; that way, the table's primary keys will certainly be part of the view's surrogate primary key for EF and thus they will guarantee uniqueness
create your own, individual pseudo primary key by having a e.g. ROW_NUMBER() column in your view, just to make sure each row has something that's unique for that row, in order to prevent EF from "short-circuiting" entities because it thinks it's already loaded that entity...