这对你有用。
创建一个类以建立以下关系:
public class ColorProduct
{
public int ProductId { get; set; }
public int ColorId { get; set; }
public Color Color { get; set; }
public Product Product { get; set; }
}
Add a ColorProduct
收藏到你的Product
and Color
课程:
public ICollection<ColorProduct> ColorProducts { get; set; }
然后使用我制作的这个扩展来删除未选择的内容并将新选择的内容添加到列表中:
public static void TryUpdateManyToMany<T, TKey>(this DbContext db, IEnumerable<T> currentItems, IEnumerable<T> newItems, Func<T, TKey> getKey) where T : class
{
db.Set<T>().RemoveRange(currentItems.Except(newItems, getKey));
db.Set<T>().AddRange(newItems.Except(currentItems, getKey));
}
public static IEnumerable<T> Except<T, TKey>(this IEnumerable<T> items, IEnumerable<T> other, Func<T, TKey> getKeyFunc)
{
return items
.GroupJoin(other, getKeyFunc, getKeyFunc, (item, tempItems) => new { item, tempItems })
.SelectMany(t => t.tempItems.DefaultIfEmpty(), (t, temp) => new { t, temp })
.Where(t => ReferenceEquals(null, t.temp) || t.temp.Equals(default(T)))
.Select(t => t.t.item);
}
使用它看起来像这样:
var model = _db.Products
.Include(x => x.ColorProducts)
.FirstOrDefault(x => x.ProductId == vm.Product.ProductId);
_db.TryUpdateManyToMany(model.ColorProducts, vm.ColorsSelected
.Select(x => new ColorProduct
{
ColorId = x,
ProductId = vm.Product.ProductId
}), x => x.ColorId);