从父实体更新子实体

Question

根据下面的场景，我想从父实体更新子实体。

我是这样处理这个问题的。

1. 从数据库中删除父级的子实体。
2. 从数据库中添加父级的新子实体。

这种方法是真的吗？

    public int SaveBasket(Addition addition)
    {
        var entity = ApplicationDbContext.Additions.Include(x => x.Basket).SingleOrDefault(x => x.AdditionId == addition.AdditionId);

        //Remove Basket
        if (entity.Basket.Count > 0)
        {
            foreach (var item in entity.Basket)
            {
                context.Entry(item).State = EntityState.Deleted;
            }

            ApplicationDbContext.SaveChanges();
        }

        //Add new basket entities from posting json data
        entity.Basket = addition.Basket;

        return ApplicationDbContext.SaveChanges();
    }

Answer 1

我认为您正在寻找以下内容：

    public int SaveBasket(Addition addition)
    {
        var entity = ApplicationDbContext.Additions.Find(addition.AdditionId); // Find by primary key

        //Remove Basket
        if (entity.Basket.Count > 0)
        {
            entity.Basket.Clear(); // Empty out the basket

            ApplicationDbContext.SaveChanges();
        }

        //Add new basket entities from posting json data
        addition.Basket.ForEach(b => entity.Basket.Add(b)); // Add the items

        return ApplicationDbContext.SaveChanges();
    }

很难说出你的数据结构是什么，但这应该会有所帮助。

更新

从您的评论看来，您想删除整个 basket 记录。

    public int SaveBasket(Addition addition)
    {
        var baskets = ApplicationDbContext.Basket.Where(b => b.AdditionId == addition.AdditionId);

        //Remove Basket
        ApplicationDbContext.Basket.RemoveRange(baskets);
        ApplicationDbContext.SaveChanges();
        ApplicationDbContext.Basket.AddRange(addition.Basket);
        return ApplicationDbContext.SaveChanges();
    }

Answer 2

根据您的模型的外观，您也许可以这样做来删除和添加子项。

public int SaveBasket(Addition addition)
{
    var dbAddition = ApplicationDbContext.Additions
        .Include(x => x.Basket)
        .SingleOrDefault(x => x.AdditionId == addition.AdditionId);

    ApplicationDbContext.Basket.RemoveRange(dbAddition.Basket);
    ApplicationDbContext.Basket.AddRange(addition.Basket);

    return ApplicationDbContext.SaveChanges();
}