Ef core many to many relationship inside a generic repository

Question

I am trying to get work with many-to-many relationship in my web application. I am using a generic repository base code.

Here my the entities

public class UserEntity : BaseEntity<int>
{
    public string EmployeeId { get; set; }
    public string FullName { get; set; }
    public string Email { get; set; }

    public virtual ICollection<UserRoleEntity> UserRoles { get; set; }
}

public class RoleEntity : BaseEntity<int>
{
    public string Name { get; set; }

    public virtual ICollection<UserRoleEntity> Users { get; set; }
}

public class UserRoleEntity : BaseEntity<Guid>
{
    public int UserId { get; set; }
    public int RoleId { get; set; }

    public virtual UserEntity UserEntity { get; set; }
    public virtual RoleEntity RoleEntity { get; set; }
}

This is context model configuration

private void ConfigureUserRole(EntityTypeBuilder<UserRoleEntity> builder)
{
    builder.ToTable("UserRole");

    //there is no need for a surrogate key on many-to-many mapping table
    builder.Ignore("Id");

    builder.HasKey(ur => new { ur.RoleId, ur.UserId });

    builder.HasOne(ur => ur.RoleEntity)
        .WithMany(r => r.Users)
        .HasForeignKey(ur => ur.RoleId);

    builder.HasOne(ur => ur.UserEntity)
        .WithMany(u => u.UserRoles)
        .HasForeignKey(ur => ur.UserId);
}

This is the main get method of my generic repository (in fact it is Chris Pratt 's implementation ) Please notice the query.Include line, the get methods of generic repository make use of EF Core's Include api to get dependent entity which comes as string parameter .

 protected virtual IQueryable<T> GetQueryable(Expression<Func<T, bool>> filter = null, Func<IQueryable<T>, IOrderedQueryable<T>> orderBy = null,
                                                    string includeProperties = null,
                                                    int? skip = null,
                                                    int? take = null)
        {
            includeProperties = includeProperties ?? string.Empty;
            IQueryable<T> query = _dbContext.Set<T>();

            if (filter != null)
            {
                query = query.Where(filter);
            }

            foreach (var includeProperty in includeProperties.Split
                (new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries))
            {
                query = query.Include(includeProperty);
            }

            if (orderBy != null)
            {
                query = orderBy(query);
            }

            if (skip.HasValue)
            {
                query = query.Skip(skip.Value);
            }

            if (take.HasValue)
            {
                query = query.Take(take.Value);
            }

            return query;
        }

And in my service, I want to get user data with its full dependents.

public class UserService : IUserService
{
    private IRepository<UserEntity> _userRepository;
    private IRepository<RoleEntity> _roleRepository;

    public UserService(IRepository<UserEntity> userRepository, IRepository<RoleEntity> roleRepository)
    {
        _userRepository = userRepository;
        _roleRepository = roleRepository;
    }
    public UserEntity GetUserData(string employeeId)
    {
        var user = _userRepository.GetFirst(u => u.EmployeeId == employeeId, includeProperties: "UserRoles");
        //var roles = _roleRepository.GetAll().ToList();

        return user;
    }
}

When the above service code executed, I get the user with its UserRole dependent, however, when I inspect UserRole 's RoleEntity dependent which I need, it is null .

• How can I get the dependent RoleEntity data just modifying the generic repository's get method?

• Secondly, the line commented in service code ( _roleRepository.GetAll() ), when it is also executed, the RoleEntity is immediately filled with its proper value. How is it happening?

Answer 1

Your include path only has a single hop from UserEntity to UserRoleEntity (via the UserRoles property. You need to include the next step to ensure you also capture the RoleEntity . To do this, change your path to UserRoles.RoleEntity , for example:

var user = _userRepository.GetFirst(
    u => u.EmployeeId == employeeId, 
    includeProperties: "UserRoles.RoleEntity");