在委托操作中设置等待的位置[重复]

Question

public enum SyncListsEnum
{
    Country = 1,
    Language = 2
}

public class SyncListsService
{
    private readonly WeCandidateContext _db;
    private readonly IRestClientFactory _factory;
    private readonly IConfigurationService _configService;

    private readonly Dictionary<SyncListsEnum, Action<IList<ExpandoObject>>> _syncLists;

    public SyncListsService(WeCandidateContext db, IRestClientFactory factory, IConfigurationService configService)
    {
        _db = db;
        _factory = factory;
        _configService = configService;

        _syncLists = new Dictionary<SyncListsEnum, Action<IList<ExpandoObject>>>()
        {
            {SyncListsEnum.Country, items =>{ new CountrySync(_db).SyncItems(items); _db.SaveChangesAsync();}},
            {SyncListsEnum.Language, items =>{ new LanguageSync(_db).SyncItems(items); _db.SaveChangesAsync();}}
        };
    }

    public async Task SyncList(string listName)
    {
        SyncListsEnum list;
        if (!Enum.TryParse(listName, true, out list)) return;


        // get list content from Recruiter 
        var items = await GetListFromRecruiter();
        // call a specific routine for each list to handle insert/update/delete 
        if (items != null)
        {
            // Synchronizes the local table with items retrieced from Recruiter.
            this._syncLists[list](items);
        }
    }
}

在这段代码中一切都是正确的，但我需要await _db.SaveChangesAsync() 而不是_db.SaveChangesAsync()。如果我将 await 运算符放在 _db.SaveChangesAsync() 前面，它会显示一个错误，例如 await 运算符只能在异步 lamda 表达式中使用强>。

现在我应该在哪里使用 async 关键字来解决这个错误。

Answer 1

把async放在你的lambda表达式前面，然后你就可以使用await了。见“can not await async lambda”