Entity Framework Skip and Take didn't translated to SQL command

Question

var allUseresInclude = _userService.Include(r => r.Profession);

var model = allUseresInclude.Select(s => new ViewModel.User
{
    Profession = s.Profession.Name,
    Id = s.Id,
    ProviderUserId = s.ProviderUserId,
    PlatformId = s.PlatformId,
    Email = s.Email,
    Password = s.Password,
    RefreshToken = s.RefreshToken,
    Name = s.Name,
    Surname = s.Surname,
    Fullname = s.Name + " " + s.Surname,
    Gender = s.Gender,
    ProfessionId = s.ProfessionId,
    BirthDate = s.BirthDate.ToString(),
    IdentityNumber = s.IdentityNumber,
    Phone = s.Phone,
    IsActive = s.IsActive,
    CreatedDate =  _common.DateTimeToTimeZone(s.CreatedDate),//.ToString("dd.MM.yyyy HH:mm"),
    EmailConfirmed = s.EmailConfirmed
});

var tt = model.OrderByDescending(o => o.CreatedDate).Skip(20).Take(30).ToList();

Model is a IQueryable variable. First, I am selecting the properties for my ViewModel then I try to filter my IQueryable. Query execution takes a while and I see correct results in UI, but in SQL the generated query doesn't have offset or limit

    SELECT [r].[CreatedDate], [r.Profession].[Name] AS [Profession], [r].[Id], [r].[ProviderUserId], [r].[PlatformId], [r].[Email], [r].[Password], [r].[RefreshToken], [r].[Name], [r].[Surname], ([r].[Name] + N' ') + [r].[Surname] AS [Fullname], [r].[Gender], [r].[ProfessionId], CONVERT(VARCHAR(100), [r].[BirthDate]) AS [BirthDate], [r].[IdentityNumber], [r].[Phone], [r].[IsActive], [r].[EmailConfirmed]
FROM [User] AS [r]
LEFT JOIN [Profession] AS [r.Profession] ON [r].[ProfessionId] = [r.Profession].[Id]

When I fire this query, it returns all the tables so I guess my skip and take doesn't work as expected. Am I doing something wrong?

Answer 1

One of the reasons for this is using.ToList() or.Select() to early. So, that means you should check if your query really producing IQueryable.

var model = allUseresInclude.Select(s => new ViewModel.User
{
    Profession = s.Profession.Name,
    Id = s.Id,
    ProviderUserId = s.ProviderUserId,
    PlatformId = s.PlatformId,
    Email = s.Email,
    Password = s.Password,
    RefreshToken = s.RefreshToken,
    Name = s.Name,
    Surname = s.Surname,
    Fullname = s.Name + " " + s.Surname,
    Gender = s.Gender,
    ProfessionId = s.ProfessionId,
    BirthDate = s.BirthDate.ToString(),
    IdentityNumber = s.IdentityNumber,
    Phone = s.Phone,
    IsActive = s.IsActive,
    CreatedDate =  _common.DateTimeToTimeZone(s.CreatedDate),//.ToString("dd.MM.yyyy HH:mm"),
    EmailConfirmed = s.EmailConfirmed
});

In your code pay attention to _common.DateTimeToTimeZone this will force Entity Framework to be executed in the memory otherwise this cannot be executed and translated to the SQL query.

If this part is executed in the application memory that means Skip and Take are executed after that in the memory as well.

You should try with some solution like this one:

var model = allUseresInclude.OrderByDescending(o => o.CreatedDate).Skip(20).Take(30).Select(s => new ViewModel.User
{
    Profession = s.Profession.Name,
    Id = s.Id,
    ProviderUserId = s.ProviderUserId,
    PlatformId = s.PlatformId,
    Email = s.Email,
    Password = s.Password,
    RefreshToken = s.RefreshToken,
    Name = s.Name,
    Surname = s.Surname,
    Fullname = s.Name + " " + s.Surname,
    Gender = s.Gender,
    ProfessionId = s.ProfessionId,
    BirthDate = s.BirthDate.ToString(),
    IdentityNumber = s.IdentityNumber,
    Phone = s.Phone,
    IsActive = s.IsActive,
    CreatedDate =  _common.DateTimeToTimeZone(s.CreatedDate),//.ToString("dd.MM.yyyy HH:mm"),
    EmailConfirmed = s.EmailConfirmed
}).ToList();