如何在C＃等待調用中使用Rx從Web檢索JSON數據

Question

我有一種方法，可以使用HttpClient調用API並以IEnumberable<Customer>形式IEnumberable<Customer> 。 該API的工作方式是一次僅返回100個客戶，並在JSON內容中提供另一個鏈接以再次獲取下一個100個客戶。

如何構造此代碼以迭代方式獲取記錄，直到獲取所有記錄，並構建一個大的IEnumerable<Customer>並從此方法返回。 我正在尋找Rx解決方案。

Task<IEnumerable<Customer>> GetCustomers(string url)
{
  HttpClient client = new HttpClient();
  HttpResponseMessage response = await client.GetAsync(url);
  response.EnsureSuccessStatusCode();
  string responseBody = await response.Content.ReadAsStringAsync();

  // TODO: Deserialize responseBody and build a new IEnumerable<Customer>
}

Json:

{
    nextRecords: '\customers\123'
    customers: [
        {
            name: 'John Doe'
        },
        {
            name: 'Mary Doe'
        }
        ]
}

Answer 1

我已將簽名從Task<IEnumerable<Customer>>更改為IObservable<Customer> ，以使其更像Rx。

您需要定義Func<JObject, IObservable<Customer>> createCustomers函數。

嘗試一下：

IObservable<Customer> GetCustomers(string url)
{
    Func<JObject, IObservable<Customer>> createCustomers = jo => { ... };
    return Observable.Create<Customer>(o =>
    {
        var final_url = url + "\\customers";
        return
            Observable
                .While(
                    () => final_url != url,
                    Observable
                        .Using(
                            () => new HttpClient(),
                            client =>
                                from x in Observable.FromAsync(() => client.GetAsync(final_url))
                                from y in Observable.Start(() =>
                                {
                                    x.EnsureSuccessStatusCode();
                                    return x;
                                })
                                from z in Observable.FromAsync(() => y.Content.ReadAsStringAsync())
                                from w in Observable.Start(() =>
                                {
                                    var j = JObject.Parse(z);
                                    final_url = url + j.Property("nextRecords").Value;
                                    return createCustomers(j);
                                })
                                from v in w
                                select v))
                .Subscribe(o);
    });
}