Entity Framework

Best Practices

• Use Select to load less data from the DB
  

  // ❌ Bad Example -> Loads all user data from DB
  var user = users.SingleOrDefault(u => u.Id == request.Id);
  var dto = user.Select(u => new UserDto(u.FirstName));
  
  // ✅ Good Example -> Loads only FirstName from DB
  users.Select(u => new UserDto(u.FirstName))
      .SingleOrDefault(u => u.Id == request.Id);
  

• Prevent a  cartesian explosion by using SplitQuery in cases where we have a lot of data getting joined. This reduces the data loaded but has some overhead and should therefore only be used when we expect to have a lot of DB in the table.
  

  // ❌ Bad Example -> Loads a blog multiple times (once for each post)
  var blogs = context.Blogs
      .Include(blog => blog.Posts)
      .ToList();
  
  // ✅ Good Example -> Loads The blog post only once
  var blogs = context.Blogs
      .Include(blog => blog.Posts)
      .AsSplitQuery() // <== 👁️
      .ToList();
  

• ````