entity framework migration seed method duplicating records - entity-framework

Question

Data model: Song - Artists (N:N)
I'm trying to seed my database, but for some reason my Artists are getting duplicate after the seed method has ran. I'm not sure why...
CreateSong("COLDPLAY", "Viva la vida", context);
CreateSong("COLDPLAY", "UP & UP", context);
CreateSong("COLDPLAY", "UP & UP", context);
CreateSong method:
public Song CreateSong(String artistName, String title, NeosicDbContext context)
{
var ret = context.Songs.FirstOrDefault(s => s.Title == title && s.Artists.FirstOrDefault(a => a.Name == artistName) != null);
if(ret != null)
{
return ret;
}
**var artists = new List<Artist>();
var artist = context.Artists.FirstOrDefault(a => a.Name == artistName);
if (artist == null)
{
artist = new Artist { Name = artistName };
context.Artists.Add(artist);
}
artists.Add(artist);**
var tags = new List<Tag>();
tags.Add(defaultTag);
ret = new Song {
Title = title,
Artists = artists,
Tags = tags
};
context.Songs.Add(ret);
//context.MarkAsModified(ret);
return ret;
}
Db result:
3 artists, while I'm only expecting one.
Tried both with context.Artists.Add(artist); and without but results remains the same

Answer 1

the problem comes here:
var artist = context.Artists.FirstOrDefault(a => a.Name == artistName);
this query systematically hits the db. But, before SaveChanges, the db is empty.
So, you should do something like:
//check the context (I would like to say the *cache*, but it is a false friend in this case)
var artist = context.Artists.Local.FirstOrDefault(a => a.Name == artistName);
if ( artist == null) {
//then hit the db
artist = context.Artists.FirstOrDefault(a => a.Name == artistName);
}