这是使用ef core在子查询中插入数据的正确方法

Question

I have a .net API using EF Core with the following entities following entities

My goal is to send an User id to the API and based on this id the application should retrieve the name from the User table and insert it on the Name table

UserRepository.cs

public int GetNameById(int userId)
{
    var result = _context.User.Where(u => u.Id == userId).Select(u => new { u.Name }).FirstOrDefault();
    ...
}

NameRepository.cs

    public void AddName(Name name)
    {
        _context.Name.Add(name);
    } 
// _context.SaveChanges() later

In the controller is where I call their respective services and they call their respective repositories. I made the search and the insert separately so I can reuse these method in the future. EF core is generating two queries, I wanted it all in single one for performance reasons, how can I do it? They already share the same context

In short I want methods that can be reusable and run all in one query. (On my real project the entities are totally different, I changed it so it would be easier to understand my issue)

Answer 1

1. method should return a string value, not int , i guess:

public string GetNameById(int id)
{
  return dbContext.Users.FirstOrDefault(q => q.Id == id)?.Name;
}

2. according your model:

    var name = new Name { Name = "New name" }; name.Id = 0; 

if Name.Id is IDENTITY column, then comment Id assignment otherwise use some value ...

public void AddName(Name name)
{
  dbContext.Names.Add(name);
}
// dbContext.SaveChanges(); somewhere