GET请求数据未更新 [英] GET request data doesn't update

问题描述

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.

I'm trying to retrieve data from an API but my variable doesn't update even if I set it as nothing before the GET request.

仅当我关闭Excel并重新打开时，变量的数据才会更新.

The data of the variable update only if I close Excel and re-open it.

对此有什么解释吗?我已经挠了很久.

Is there any explanation for it? I've been scratching my head for so long.

这是代码

Sub getJsonResult()
    Dim objRequestt As Object
    Dim strUrl As String
    Dim blnAsync As Boolean
    Dim strUrlXBTUSD As String
    Dim strResponse As String
    Dim jsonText As String
    Dim jsonObject As Object, item As Object
    Dim i As Integer

    'setting up the variable to 0 or nothing

    strUrlXBTUSD = ""
    strResponsee = ""
    jsonText = ""
    i = 0
 blnAsync = False
 Set item = Nothing
 Set jsonObject = Nothing
 Set objRequestt = Nothing
 Set objRequestt = CreateObject("MSXML2.XMLHTTP")
    strUrlXBTUSD = "https://www.bitmex.com/api/v1/orderBook/L2?symbol=XBTUSD&depth=3"
    blnAsync = True


    'Starting the GET request

    ThisWorkbook.Activate
    With objRequestt
        .Open "GET", strUrlXBTUSD, blnAsync
        .SetRequestHeader "Content-Type", "application/json"
        .send
        strResponse = .responseText 'here the response is always the same except if i Close Excel
           Debug.Print strResponsee
    End With
End Sub

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.

At the end "strResponse" is always the same even after several F5 refresh. I can see that the data are no longer accurate on a web browser. I'd like the VBA program to get accurate data and refresh without closing Excel.

该怎么做?

推荐答案

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，但我过去在此方面取得了很好的成功).确保您的异步参数始终为False，并在测试之间留出更多时间.我注意到有时价格变动缓慢，因此由于间隔太短/尝试次数不足，您可能会错过价格变动.但是您会注意到size的变化.您应该将最大超时时间添加到循环进入底部脚本.

You can add an instruction to avoid being served cached results (server can ignore this but I have had good success with this in the past). Make sure your async argument is always False and leave more time between tests. I notice that sometimes the prices are slow to change so you may miss the change due to too small an interval/not enough attempts. You will notice the size change though. You should add a max timeout to the loop in the bottom script.

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"

        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

---

在这里，通过循环直到退货中第一个商品的价格发生变化，证明它是一种漫长而乏味的方法.我使用添加到项目和VBE中的 jsonconverter.bas >工具>参考> Microsoft脚本运行时参考.

---

Here is a long and tedious way of proving it by looping until price of first item in return collection changes. I use jsonconverter.bas added to project and VBE > Tools > References > Microsoft Scripting Runtime reference.

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"

    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

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