Question

我正在尝试从API检索数据，但是即使在GET请求之前将其设置为空，我的变量也不会更新。

仅当我关闭Excel并重新打开时，变量的数据才会更新。

对此有什么解释吗？我已经挠了很久。

这是代码

int main()
{
    Derived* derived = new Derived(); 
    Base* base = (Base*) derived; //upcast 
    Derived* derived2 = (Derived*) base; //downcast

    return 0;
}

最后，即使多次刷新F5，“ strResponse”也始终相同。我可以看到数据在网络浏览器上不再准确。我希望VBA程序在不关闭Excel的情况下获取准确的数据并刷新。

该怎么做？

Answer 1

您可以添加一条指令，以免获得缓存的结果（服务器可以忽略此结果，但是我过去在此方面取得了很好的成功）。确保异步参数始终为False，并在测试之间留出更多时间。我注意到有时价格变化缓慢，因此由于间隔太短/尝试次数不足，您可能会错过价格变化。不过，您会注意到size的变化。您应该在底部脚本的循环中添加max timeout。

还删除了匈牙利符号。

Option Explicit

Public Sub getJsonResult()
    Dim http As Object
    Dim urlXBTUSD As String
    Dim response As String
    Dim j As Long
    Const ASYNC_ARG As Boolean = False

    Set http  = CreateObject("MSXML2.XMLHTTP")
    For j = 1 To 10
        response = vbNullString
        urlXBTUSD = "https://www.bitmex.com/api/v1/orderBook/L2?symbol=XBTUSD&depth=3"

        ThisWorkbook.Activate
        With http 
            .Open "GET", urlXBTUSD,  ASYNC_ARG
            .setRequestHeader "Content-Type", "application/json"
            .setRequestHeader "If-Modified-Since", "Sat, 1 Jan 2000 00:00:00 GMT"
            .send
            response = .responseText
            Debug.Print response
        End With
        Application.Wait Now + TimeSerial(0, 0, 15)
    Next
End Sub

通过循环直到退货集合中的第一件商品的价格发生变化，这是一种冗长而乏味的证明方式。我使用jsonconverter.bas添加到项目中，并使用VBE>工具>参考> Microsoft脚本运行时参考。

Option Explicit

Public Sub getJsonResult()
    Dim http  As Object
    Dim urlXBTUSD As String
    Dim response As String
    Dim j As Long
    Const ASYNC_ARG As Boolean = False
    Dim price As String, firstValue As String

    Set http  = CreateObject("MSXML2.XMLHTTP")
    urlXBTUSD = "https://www.bitmex.com/api/v1/orderBook/L2?symbol=XBTUSD&depth=3"

    ThisWorkbook.Activate
    With http 
        .Open "GET", urlXBTUSD,  ASYNC_ARG
        .setRequestHeader "Content-Type", "application/json"
        .setRequestHeader "If-Modified-Since", "Sat, 1 Jan 2000 00:00:00 GMT"
        .send
         firstValue = JsonConverter.ParseJson(.responseText)(1)("price")
        Debug.Print  firstValue
        Do
            .Open "GET", urlXBTUSD, blnAsync
            .setRequestHeader "Content-Type", "application/json"
            .setRequestHeader "If-Modified-Since", "Sat, 1 Jan 2000 00:00:00 GMT"
            .send
            price = JsonConverter.ParseJson(.responseText)(1)("price")
            Application.Wait Now + TimeSerial(0, 0, 5)
        Loop While price = firstValue
        Debug.Print price
    End With
End Sub

Answer 2

这是出于诊断目的。

On Error Resume Next
Set File = WScript.CreateObject("Msxml2.XMLHTTP.6.0")
File.Open "GET", "https://www.google.com.au/search?q=cat", False
File.setRequestHeader "User-Agent", "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 1.1.4322; .NET CLR 3.5.30729; .NET CLR 3.0.30618; .NET4.0C; .NET4.0E; BCD2000; BCD2000)"
File.Send

wscript.echo "==================" 
    wscript.echo "" 
    wscript.echo "Error " & err.number & "(0x" & hex(err.number) & ") " & err.description 
    wscript.echo "Source " & err.source 
    wscript.echo "" 
    wscript.echo "Server Response " & File.Status & " " & File.StatusText
    wscript.echo    File.getAllResponseHeaders
    wscript.echo    File.ResponseBody

GET请求数据未更新

2 个答案: