需要帮助使用 VBA 中的 post 方法发布多部分表单数据答案

【问题标题】：Need help to post multipart form data using the post method in VBA需要帮助使用 VBA 中的 post 方法发布多部分表单数据
【发布时间】：2017-03-31 00:44:08
【问题描述】：

我正在尝试使用 API 来更新在线数据库。

API 由法国网站托管，使用细节很少，没有示例。

这是他们提供的信息

The query must be sent as a "multipart / form-data" html form using the "POST" method. 
Input parameters: 
ssid : (type "text") user's ScreenScraper identifier 
sspassword : (type "text") ScreenScraper password of the user 
gameid : (type "text") numerical identifier of the game on ScreenScraper 
or 
romid ( "text") numeric ID of the Roma on ScreenScraper 

to propose a textual info: 
modiftypeinfo ( "text") type of information sent (see list "modiftypeinfo") 
modifregion ( "text"





<html>
  <head>
  <META http-equiv="Content-Type" content="text/html; charset=UTF-8"> 
  <META http-equiv="content-language" content="fr"> 
  <title></title>
  </head> 
  <body> 
    <form name="myform" id="myform" method="post" enctype="multipart/form-data" action="https://www.screenscraper.fr/api/botProposition.php?ssid=xxx&sspassword=yyy"> 
      <input type="text" name="gameid" value="3"> 
      <input type="text" name="modiftypeinfo" value="description">
      <input type="text" name="modifregion" value="">   
      <input type="text" name="modiflangue" value="fr"> 
      <input type="text" name="modifversion" value=""> 
      <input type="text" name="modiftexte" value="ici, le synopsis du jeu ! ne pas valider, c'est un test ;)"> 
      <input type="text" name="modifsource" value="botProposition / source de l'info">
      <input type="submit" value="envoyer"> 
    </form>

  <script> 
    document.getElementById("myform").submit();
    </script>

  </body>
</html>

这是我整理的代码：

Sub Post_Detail()

    Dim xmlhttp As Object, response As String, SendString As String

    Set xmlhttp = CreateObject("MSXML2.XMLHTTP.6.0")

    '~~> Indicates that page that will receive the request and the type of request being submitted
    xmlhttp.Open "POST", "https://www.screenscraper.fr/api/botProposition.php?ssid=xxx&sspassword=yyy", False

    '~~> Indicate that the body of the request contains form data
    xmlhttp.setRequestHeader "Content-Type", "text/html; charset=UTF-8"
    xmlhttp.setRequestHeader "enctype", "multipart/form-data"

    '~~> Send the data as name/value pairs
    SendString = "&type=text&name=gameid&value=185882"
    SendString = SendString & "&type=text&name=modiftypeinfo&value=genres"
    SendString = SendString & "&type=text&name=modiftexte&value=Sports"
    SendString = SendString & "&type=submit&value=envoyer"
    Debug.Print SendString
    xmlhttp.send SendString

    response = xmlhttp.responseText
    MsgBox response

    Set xmlhttp = Nothing

End Sub

我不确定如何处理这部分：说明中的form name="myform" id="myform"，我不确定我通过构建字符串的请求是否接近正确。

您将无法在没有登录的情况下运行，它会返回密码无效错误。

【问题讨论】：

HTML 表单的名称和 ID 不会随提交一起发送，因此您可以将其省略。您唯一需要的是输入的名称和值（因此也不要使用“type=text”）。如果您有包含该表单的页面，您可以使用（例如）Fiddler 或浏览器的开发者工具来查看提交表单时发送的内容。

标签： vba post web

【解决方案1】：

multipart/form-data 的结构在RFC7578 中描述。有一个样本：

POST /form.html HTTP/1.1
Host: server.com
Referer: http://server.com/form.html
User-Agent: Mozilla
Content-Type: multipart/form-data; boundary=-------------573cf973d5228
Content-Length: 288
Connection: keep-alive
Keep-Alive: 300


---------------573cf973d5228
Content-Disposition: form-data; name="field"

text
---------------573cf973d5228
Content-Disposition: form-data; name="file"; filename="sample.txt"
Content-Type: text/plain

Content file
---------------573cf973d5228--

试试下面的代码来做 POST XHR：

Sub POST_multipart_form_data()
    
    Dim oFields As Object
    Dim sBoundary As String
    Dim sPayLoad As String
    Dim sName As Variant
    
    Set oFields = CreateObject("Scripting.Dictionary")
    With oFields
        .Add "gameid", "3"
        .Add "modiftypeinfo", "description"
        .Add "modifregion", ""
        .Add "modiflangue", "fr"
        .Add "modifversion", ""
        .Add "modiftexte", "ici, le synopsis du jeu ! ne pas valider, c'est un test ;)"
        .Add "modifsource", "botProposition / source de l'info"
    End With
    sBoundary = String(6, "-") & Replace(Mid(CreateObject("Scriptlet.TypeLib").GUID, 2, 36), "-", "")
    sPayLoad = ""
    For Each sName In oFields
        sPayLoad = sPayLoad & "--" & sBoundary & vbCrLf
        sPayLoad = sPayLoad & "Content-Disposition: form-data; name=""" & sName & """" & vbCrLf & vbCrLf
        sPayLoad = sPayLoad & oFields(sName) & vbCrLf
    Next
    sPayLoad = sPayLoad & "--" & sBoundary & "--"
    With CreateObject("MSXML2.XMLHTTP")
        .Open "POST", "https://www.screenscraper.fr/api/botProposition.php?ssid=xxx&sspassword=yyy", False
        .setRequestHeader "Content-Type", "multipart/form-data; boundary=" & sBoundary
        .setRequestHeader "Content-Length", LenB(sPayLoad)
        .send (sPayLoad)
        MsgBox .responseText ' Erreur de login : Verifier vos identifiants !
    End With
    
End Sub

所以代码生成的payload数据如下：

--------CFE02291483D4B3EB3B1A92257838D94
Content-Disposition: form-data; name="gameid"

3
--------CFE02291483D4B3EB3B1A92257838D94
Content-Disposition: form-data; name="modiftypeinfo"

description
--------CFE02291483D4B3EB3B1A92257838D94
Content-Disposition: form-data; name="modifregion"


--------CFE02291483D4B3EB3B1A92257838D94
Content-Disposition: form-data; name="modiflangue"

fr
--------CFE02291483D4B3EB3B1A92257838D94
Content-Disposition: form-data; name="modifversion"


--------CFE02291483D4B3EB3B1A92257838D94
Content-Disposition: form-data; name="modiftexte"

ici, le synopsis du jeu ! ne pas valider, c'est un test ;)
--------CFE02291483D4B3EB3B1A92257838D94
Content-Disposition: form-data; name="modifsource"

botProposition / source de l'info
--------CFE02291483D4B3EB3B1A92257838D94--

请注意，每个部分的可选“Content-Type”标头字段默认为“text/plain”。正如您在评论中看到的那样，我的响应是登录错误：

Erreur de login : Verifier vos identifiants ！

我唯一不明白的是为什么他们将提交指定为multipart/form-data？即使没有附加文件！使用以下代码以application/x-www-form-urlencoded 发送数据要容易得多：

Sub POST_application_x_www_form_urlencoded()
    
    Dim oFields As Object
    Dim sPayLoad As String
    Dim sName As Variant
    
    Set oFields = CreateObject("Scripting.Dictionary")
    With oFields
        .Add "gameid", "3"
        .Add "modiftypeinfo", "description"
        .Add "modifregion", ""
        .Add "modiflangue", "fr"
        .Add "modifversion", ""
        .Add "modiftexte", "ici, le synopsis du jeu ! ne pas valider, c'est un test ;)"
        .Add "modifsource", "botProposition / source de l'info"
    End With
    For Each sName In oFields
        oFields(sName) = sName & "=" & EncodeUriComponent(oFields(sName))
    Next
    sPayLoad = Join(oFields.Items(), "&")
    With CreateObject("MSXML2.XMLHTTP")
        .Open "POST", "https://www.screenscraper.fr/api/botProposition.php?ssid=xxx&sspassword=yyy", False
        .setRequestHeader "Content-Type", "application/x-www-form-urlencoded"
        .setRequestHeader "Content-Length", LenB(sPayLoad)
        .send (sPayLoad)
        MsgBox .responseText ' Erreur de login : Verifier vos identifiants !
    End With
    
End Sub

Function EncodeUriComponent(sText As String) As String
    Static oHtmlfile As Object
        
    If oHtmlfile Is Nothing Then
        Set oHtmlfile = CreateObject("htmlfile")
        oHtmlfile.parentWindow.execScript "function encode(s) {return encodeURIComponent(s)}", "jscript"
    End If
    EncodeUriComponent = oHtmlfile.parentWindow.encode(sText)
End Function

而代码生成的payload数据如下：

gameid=3&modiftypeinfo=description&modifregion=&modiflangue=fr&modifversion=&modiftexte=ici%2C%20le%20synopsis%20du%20jeu%20!%20ne%20pas%20valider%2C%20c'est%20un%20test%20%3B)&modifsource=botProposition%20%2F%20source%20de%20l'info

错误响应与我的第一种方法相同。

【讨论】：

OMG 我已经放弃了，非常感谢多部分表单数据正在工作，它是多部分的原因是您可以在需要时提交一个文件（上传艺术品）。

【解决方案2】：

未经测试：

Sub Post_Detail()

    Dim xmlhttp As Object, response As String, SendString As String

    Set xmlhttp = CreateObject("MSXML2.XMLHTTP.6.0")

    '~~> Indicates that page that will receive the request and the type of request being submitted
    xmlhttp.Open "POST", "https://www.screenscraper.fr/api/botProposition.php?ssid=xxx&sspassword=yyy", False

    '~~> Indicate that the body of the request contains form data
    xmlhttp.setRequestHeader "enctype", "multipart/form-data"

    '~~> Send the data as name/value pairs
    SendString = "gameid=185882" & _
                "&modiftypeinfo=genres" & _
                "&modiftexte=Sports"

    Debug.Print SendString
    xmlhttp.send SendString

    response = xmlhttp.responseText
    MsgBox response

    Set xmlhttp = Nothing

End Sub

如果没有 name 属性，我认为提交按钮不会包含在 POST 中。

【讨论】：

谢谢蒂姆，同样的问题。调试输出现在是 gameid=185882&modiftypeinfo=genres&modiftexte=Sports。不幸的是，当出现错误时返回的字符串不是错误，它只是空白，确实很难分析。
如果您在执行 POST 时运行 Fiddler，它可能会为您提供一些关于正在发生的事情的线索。
我运行了 fiddler，运行代码时它没有返回任何结果。我只能假设某些事情正在阻止 Fiddler 在我的工作机器上获取 HTTPS。我回家后会再试一次。