CODEWITHSUNDEEP
asp.net-mvcasp.net-web-apiindexingentity-framework-5iqueryable
Mando
Mando

Reputation: 11722

WebAPI controller with IQueryable<T> throws "LINQ to Entities does not recognize the method" error

I'm fetching the data with OData syntax: http://server.com/api/users?$skip=20&$top=10

I'm trying to add index to every fetched entity in my Web API Controller. Every time I'm getting the following error:

LINQ to Entities does not recognize the method 'System.Linq.IQueryable1[WebPortal.Models.UserDto] Select[UserInDatabase,UserDto](System.Linq.IQueryable1[DataContext.UserInDatabase], System.Linq.Expressions.Expression1[System.Func3[DataContext.Media,System.Int32,WebPortal.Models.UserDto]])' method, and this method cannot be translated into a store expression.","ExceptionType":"System.NotSupportedException"

As I understand I couldn't use Select(u, index)=> selector while working with Entity Framework context (works fine for in memory collection). Unfortunately I'm using it to expose my collection via OData + QueryableAttribute:

public class UsersController : ApiController
{
    [Queryable]
    public IQueryable<UserDto> Get()
    {
        return _repository.Users
                .Select((u, i) => new UserDto
                    {
                        Index = i,
                        Name = u.Name,
                        Age = u.Age
                    })
                .AsQueryable();
    }
}

How can I modify fetch process to continue to use OData syntax and have ability to return entities with index to requesting side?

my entities:

public class UserInDatabase
{
    public string Name { get; set; }
    public int Age { get; set; }
}

public class UserDto
{
    public int Index { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
}

TIA

Upvotes: 0

Views: 700

Answers (1)

Phil Sandler
Phil Sandler

Reputation: 28046

Try changing this line:

return _repository.Users

to

return _repository.Users.AsEnumerable()

This should force the query to execute before projecting onto your DTO.

Upvotes: 1

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