c# - 在 C# 中链接多个相同方法的调用

Question

我有一个更新方法，它获取最后一个事件项目并使用新值克隆它并将事件标志设置为 true。我的问题是 update 方法被多个 web api 方法调用，所以最后一个事件项目并不总是相同的。我最终遇到了多个事件项目和数据不一致的问题。所以我正在考虑链接所有调用来解决这个问题，但我不知道从哪里开始。`

[HttpPost]
[Route("Route2")]
[ValidateModel]
public async Task<HttpResponseMessage> Post(string contractReference, [FromBody] Family input)
{
    return await CallPartialUpdate(contractReference, p => p.Family = input);
}


[HttpPost]
[Route("Route3")]
[ValidateModel]
public async Task<HttpResponseMessage> Post(string contractReference, [FromBody] Address input)
{
    return await CallPartialUpdate(contractReference, p => p.Address = input);
}



private async Task<HttpResponseMessage> CallPartialUpdate(string reference, Item itemToUpdate)
{
    try
    {
        var existingItem = _bContext.RetrieveLastActive(reference);

        if (existingItem == null)
            return Request.CreateResponse(HttpStatusCode.NotFound);

        var newRecord = existingItem.Document.Clone();

        newRecord.update(itemToUpdate);
        newRecord.active = true;

        await _bContext.PutDocumentAsync(newRecord, reference);

        return Request.CreateResponse(HttpStatusCode.Created);
    }
    catch (System.Exception exception)
    {
        return Request.CreateErrorResponse(HttpStatusCode.InternalServerError, exception.Message);
    }
}`

基于@Asti 的回答，我创建了一个带有 Rx observable 的单元测试，但我在最后一项中仍然存在数据不一致，所以我如何让它工作以及我如何获得 callPartialUpdate() 的结果谢谢

    [TestFixture]
public class Concurrency
{

    [Test]
    public async Task Update_Should_Always_Change_Last_Item()
    {
        var observer = Observable.Timer(TimeSpan.FromMilliseconds(1));
        var items = new List<Item>()
        {
            new Item() { FirstName = "AA", LastName = "BB" , IsActive = true },
            new Item() { FirstName = "A", LastName = "A" , IsActive = false },
        };
        await Task.Run(() =>
        {
             Parallel.Invoke(async () => await observer.Select(item => Observable.FromAsync(ct => UpdateItem(items, new Item() { FirstName = "AAA" })))
                             .Concat(),
                             async () => await observer.Select(item => Observable.FromAsync(ct => UpdateItem(items, new Item() { LastName = "BBB" })))
                             .Concat());
        });
        var lastItem = items.Single(w => w.IsActive);
        Assert.AreEqual("AAA", lastItem.FirstName);
        Assert.AreEqual("BBB", lastItem.LastName);
    }


    public async Task<bool> UpdateItem(List<Item> items, Item itemToUpdate)
    {
        return await Task.Run(() => update(items, itemToUpdate));
    }

    private bool update(List<Item> items, Item itemToUpdate)
    {
        var lastItem = items.Single(w => w.IsActive == true);
        lastItem.IsActive = false;
        var newItem = new Item()
        {
            FirstName = string.IsNullOrEmpty(itemToUpdate.FirstName) ? lastItem.FirstName : itemToUpdate.FirstName,
            LastName = string.IsNullOrEmpty(itemToUpdate.LastName) ? lastItem.LastName : itemToUpdate.LastName,
            IsActive = true
        };

        items.Add(newItem);
        return true;
    }
}

Answer 1

对于更新序列，无论是可枚举的还是可观察的:

        updates
            .Select(item => Observable.FromAsync(ct => CallPartialUpdate(item)))
            .Concat();

如果你想以基于 Rx 的 API 为目标，那么

• 让方法调用返回 observable
• 等待可观察对象而不是任务
• 观察专用调度程序以部分排序工作单元