Question

In the following code, I am trying to get a profile for the user that is currently logged in.

Dim userProfile = db1.UserProfiles.Where(Function(p) p.UserId = Membership.GetUser.ProviderUserKey).Single

The error is “LINQ to Entities does not recognize the method ‘System.Object CompareObjectEqual(System.Object, System.Object, Boolean)’ method, and this method cannot be translated into a store expression.”

Does anyone know what’s wrong with this, or is there a better way… And, how can I make this more secure; i.e. add a condition if no record is found?

I am using VB ASP.NET MVC 3.

Thank you.

Edit:

Here’s my new code:

        Dim db1 As UserProfileDbContext = New UserProfileDbContext
        Dim user = Membership.GetUser()
        Dim key As Guid = user.ProviderUserKey
        Dim finalKey = key.ToString
        Dim userProfile = db1.UserProfiles.Where(Function(p) p.UserId = finalKey).Single
        Dim companyId = userProfile.CompanyId

Answer 1

L2E is trying to render your lamba expression (p) p.UserId = Membership.GetUser.ProviderUserKey in to an SQL Expression which it can use to hit the database.

However, Membership.GetUser() is a .NET method. L2E is complaining that it doesn’t know how to render this method in to SQL syntax.

Try this instead:

Dim user = Membership.GetUser()
Dim userProfile = db1.UserProfiles.Where(Function(p) p.UserId = user.ProviderUserKey).Single

edit: MembershipUser.ProviderUserKey is a CLR Object. SQL can’t compare two objects, so you’ll need to strong type it before running the expression. For example, if your user key is a String:

Dim user = Membership.GetUser()
Dim key as String= user.ProviderUserKey
Dim userProfile = db1.UserProfiles.Where(Function(p) p.UserId = key).Single

This should work better because a simple equality expression = is understood by L2E and can be rendered in to an equivilent SQL expression, something like:

SELECT * FROM Profiles WHERE UserId = @Argument, where the @Argument is supplied by entity framework.

Also as an aside, L2E will group chained calls until the end, so an expression like:

db1.UserProfiles.Skip(10).Take(30).Where(Function(p) p.UserId = Membership.GetUser.ProviderUserKey)

… would still fail, because L2E will combine the Skip Take and Where components in to a single SQL expression. You can force L2E to hit the server by calling ToArray ToList or ToDictionary. That expression could be made valid by changing it to:

db1.UserProfiles.Skip(10).Take(30).ToArray().Where(Function(p) p.UserId = Membership.GetUser.ProviderUserKey)

The ToArray forces the execution of the SQL statement, giving you a .NET Array which does support complex lambas.