LINQ to Entities does not recognize the method. And this method cannot be translated into a store expression

Question

when i try to run the code

public static DalUser ToDalUser(this User ormUser)
    {
        return new DalUser()
        {
            Id = ormUser.Id,
            FirstName = ormUser.FirstName,
            LastName = ormUser.LastName,
            About = ormUser.About,
            Email = ormUser.Email,
            Password = ormUser.Password,
            Roles = ormUser.Roles.Select(role => role.ToDalRole())
        };
    }

error occurs

Additional information: LINQ to Entities does not recognize the method 'DAL.Interface.DTO.DalUser ToDalUser(ORM.User)' method, and this method cannot be translated into a store expression.

in View

@foreach (var item in Model)
{
    <tr>
        <td>
            @Html.DisplayFor(modelItem => item.FirstName)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.LastName)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Email)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.About)
        </td>
        <td>
            @Html.DisplayTextFor(modelItem => item.Role)
        </td>
    </tr>
}

what's the problem? please, help!

`.ToDalRole()` cannot be mapped to SQL. You'd need to map post retrieval. — David L, Aug 18 '16 at 19:40
Possible duplicate of [LINQ to Entities does not recognize the method 'System.String ToString()' method, and this method cannot be translated into a store expression](http://stackoverflow.com/questions/5899683/linq-to-entities-does-not-recognize-the-method-system-string-tostring-method) — David L, Aug 18 '16 at 19:40
@DavidL sorry, but i don't understand, how to do this. can you explain me in detail, please? — Pavel Yakimovich, Aug 18 '16 at 19:43
I removed that prior comment since it referenced a deeper method call than the one in the actual error. — Anthony Pegram, Aug 18 '16 at 19:48
@Kevin but it's written that userEntity.Role implements IEnumerable — Pavel Yakimovich, Aug 18 '16 at 19:52
@PavelYakimovich can you post the code that is throwing the exception, i.e. the query you are trying to run? That would help the community provide feedback. — Mike Sackton, Aug 18 '16 at 19:55
@MikeSackton i don't even know. i just try to run my asp.net mvc app and this error occurs before start — Pavel Yakimovich, Aug 18 '16 at 20:02

score 0 · Answer 1 · answered Aug 18 '16 at 20:23

Depending on how many Roles you have, if not that many you should be able to do this:

Roles = ormUser.Roles
  .ToArray()
  .Select(role => role.ToDalRole())

The reason being the ToArray() method will load all the Roles into memory before calling Select. If you have thousands (or even hundreds) this is not recommended.

LINQ to Entities does not recognize the method. And this method cannot be translated into a store expression

1 Answers1