所以我有两个对象
// First Object
public class Record{
public int RecordId { get; set;}
public virtual ICollection<Country> CountryCollection { get; set; }
}
// Second Object
public class Country{
public int CountryId { get; set;}
public virtual ICollection<Record> Records{ get; set; }
[Index("UI_CountryName", IsUnique = true)]
public string CountryName { get; set; }
}
..
// And my map configuration
public class RecordMap: EntityTypeConfiguration<Record>
{
HasMany(r => r.CountryCollection)
.WithMany(c => c.Records)
.Map(t => t.ToTable("RecordCountryMap","dbo").MapRightKey("CountryId").MapLeftKey("RecordId"));
}
因此,当我尝试使用以下代码将新记录插入record.CountryCollection时,问题就出现了
newRevisionRec.CountryCollection = new Collection<Country>();
foreach (var country in record.Countries)
{
newRevisionRec.CountryCollection.Add(new Country
{
CountryId = country.CountryId,
CountryName = country.CountryName,
});
}
最终发生的是,每次我这样做时,EF都试图创建新的国家记录,这是一个独特的约束例外。关于如何防止国家被拯救,有什么想法吗?
在下面的代码中,您正在创建一个新的Country对象,该对象将被Entity视为重复对象,因为它是管理关系的对象。
newRevisionRec.CountryCollection = new Collection<Country>();
foreach (var country in record.Countries)
{
newRevisionRec.CountryCollection.Add(new Country
{
CountryId = country.CountryId,
CountryName = country.CountryName,
});
}
相反,你想把它已经知道的对象传给它,让它重用它们:
foreach (var country in db.Countries.Where(t => t. ...))
{
newRevisionRec.CountryCollection.Add(country);
}