重複條目

Question

爲什麼以下內容會爲策略&部分生成重複條目？任何指導將不勝感激。

public ActionResult Create(Program program) 
{ 
    db.Programs.Add(program); 

    Strategy strategy = db.Strategies.Where(s => s.Name == program.Strategy.Name).SingleOrDefault(); 
    Segment segment = db.Segments.Where(m => m.Name == program.Segment.Name).SingleOrDefault(); 

    // Make sure not to save duplicate entries of segment & strategy 
    if (strategy != null) 
    { 
     program.Strategy = strategy; 
     db.Entry(strategy).State = EntityState.Unchanged; 
    } 

    if (segment != null) 
    { 
     program.Segment = segment; 
     db.Entry(segment).State = EntityState.Unchanged; 
    } 

    db.SaveChanges(); 
} 

Answer 1

嘗試

db.Entry(strategy).State = EntityState.Unchanged; 

和

db.Entry(segment).State = EntityState.Unchanged;