entity-framework - EntityState.Deleted 正在从我的列表中删除项目

Question

当我设置 db.Entry(episode).State = EntityState.Deleted EF 从我的列表中删除剧集并抛出 collection was modified 枚举操作可能无法执行。

这是我的代码:

public async Task UpdateAsync(List<Episode> episodes)
{
    using (var db = new DbContext())
    {
        var serie = await db.Series.Include(s => s.Episodes).SingleOrDefaultAsync(s => s.Id == id);

        foreach (var episode in serie.Episodes)
        {
            var modifiedEpisode = episodes.Where(e => e.Id == episode.Id).SingleOrDefault();

            //was deleted
            if (modifiedEpisode == null)
            {
                db.Entry(episode).State = EntityState.Deleted;// episode is removed from serie.Episodes throwing exception
                continue;
            }
        }

        var addedEpisodes = episodes.Where(v => v.Id == Guid.Empty).ToList();
        serie.Episodes.AddRange(addedEpisodes);

        await db.SaveChangesAsync();
    }
}

如何删除剧集？

Answer 1

正如 Shiraz Bhaiji 所说，您不能从列表中删除项目，而该列表是 foreach 语句的来源。一个简单的 ToList() 可以解决你的问题

 foreach (var episode in serie.Episodes.ToList())
        {
            var modifiedEpisode = episodes.Where(e => e.Id == episode.Id).SingleOrDefault();

            //was deleted
            if (modifiedEpisode == null)
            {
                db.Entry(episode).State = EntityState.Deleted;// episode is removed from serie.Episodes throwing exception
                continue;
            }
        }

Shiraz Bhaiji 的回答也是正确的!