I've found that when using lazy child collections, the collection is loaded when an item is added directly to the context. This is a problem because the collection may be very large. I think EF wants to update the in memory collection with the new item, but it should realize that Í didn't request the collection.<br /><br />One workaround is to make the property non virtual. Another is to make the parent class internal (WTF!?)<br /><br />Here's code that reproduces the issue. Put a breakpoint in the last Add() call and confirm with SQL Server Profiler that all citizens (possible million, depends on the country) are loaded.<br /><br />public class Country // make internal to avoid spurious select<br />{<br /> public virtual int CountryID { get; set; }<br /><br /> public virtual ICollection<Citizen> Countries { get; set; } // make non virtual to avoid select<br />}<br />public class Citizen<br />{<br /> public virtual int CitizenID { get; set; }<br /><br /> public virtual int CountryID { get; set; }<br />}<br />class Context : DbContext<br />{<br /> public DbSet<Country> Countries { get; set; }<br /> public DbSet<Citizen> Citizens { get; set; }<br />}<br />class Program<br />{<br /> static void Main()<br /> {<br /> using (var db = new Context())<br /> {<br /> db.Countries.Add(new Country());<br /> db.SaveChanges();<br /> }<br /> using (var db = new Context())<br /> {<br /> var c = db.Countries.FirstOrDefault();<br /> db.Citizens.Add(new Citizen { CountryID = c.CountryID, }); // loads all citizens of the country<br /> }<br /> }<br />}<br />
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