不应该这么难!我准备放弃EF了...
我的模型有周刊版本。每个版本可以有许多分类广告。每个分类可以出现在一个或多个版本中。我的模型:
public class Classifieds
{
[Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ClassifiedId { get; set; }
...
public virtual ICollection<EditionModel> Editions { get; set; }
}
public class EditionModel
{
[Key, DatabaseGenerated(DatabaseGeneratedOption.None)]
public int EditionId { get; set; } // This is YYYYWW, WW = week number
public Date PublicationDate { get; set; }
public virtual ICollection<Classifieds> Classifieds { get; set; }
}
OnModelCreating 重写:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<EditionModel>()
.Property(z => z.EditionId)
.HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);
modelBuilder.Entity<EditionModel>()
.HasMany(c => c.Classifieds)
.WithMany(d => d.Editions)
.Map(x =>
{
x.MapLeftKey("EditionId");
x.MapRightKey("ClassifiedId");
x.ToTable("EditionModelClassifieds");
});
base.OnModelCreating(modelBuilder);
}
创建分类操作代码(HTTP put):
public async Task<ActionResult> Create(Classifieds classifieds, int[] EditionList)
{
var allPubs = PopulateEditionList(); // Current and next 12 editions
db.Set<Classifieds>().Attach(classifieds);
db.Entry(classifieds).Collection(x => x.Editions).Load();
foreach (var p in EditionList)
{
var anEd = (from x in allPubs where x.EditionId == p select x).Single();
classifieds.Editions.Add(anEd);
}
...
if (ModelState.IsValid)
{
var ads = db.Classifieds.Add(classifieds);
await db.SaveChangesAsync().ConfigureAwait(false);
return View("Receipt", classifieds);
}
...
}
提交新的分类广告后,我得到
Violation of PRIMARY KEY constraint 'PK_dbo.EditionModels'.
Cannot insert duplicate key in object 'dbo.EditionModels'.
为什么 EF 坚持要在 EditionModels 中插入重复行,而不是仅仅将联结表行链接到其中的现有行?我该如何解决这个问题?