在ExcelVBA中解析JSON

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我有同样的问题EXCEL VBA:解析的JSON对象循环却找不到任何解决办法。我的JSON有嵌套的对象,所以建议的解决方案,比如VBJSON和VBA-json,对我不起作用。我还修复了其中一个函数的正常工作,但是由于doProcess函数的许多递归,结果是调用堆栈溢出。

最好的解决方案似乎是原始文章中看到的jsondecode函数。它非常快速且高效;我的对象结构都在一个通用的VBA对象中,它的类型是JScriptTypeInfo。

目前的问题是,我无法确定对象的结构,因此,我不知道每个泛型对象中驻留的键。我需要循环遍历通用的VBA对象来获取键/属性。

如果我的解析javascript函数能够触发一个VBA函数或子函数,那就太好了。

提问于
用户回答回答于

如果想在ScriptControl,可以添加一些帮助方法来获取所需的信息。JScriptTypeInfo对象有点不幸:它包含所有相关信息(如您在守望但似乎不可能用VBA实现它。但是,Javascript引擎可以帮助我们:

Option Explicit

Private ScriptEngine As ScriptControl

Public Sub InitScriptEngine()
    Set ScriptEngine = New ScriptControl
    ScriptEngine.Language = "JScript"
    ScriptEngine.AddCode "function getProperty(jsonObj, propertyName) { return jsonObj[propertyName]; } "
    ScriptEngine.AddCode "function getKeys(jsonObj) { var keys = new Array(); for (var i in jsonObj) { keys.push(i); } return keys; } "
End Sub

Public Function DecodeJsonString(ByVal JsonString As String)
    Set DecodeJsonString = ScriptEngine.Eval("(" + JsonString + ")")
End Function

Public Function GetProperty(ByVal JsonObject As Object, ByVal propertyName As String) As Variant
    GetProperty = ScriptEngine.Run("getProperty", JsonObject, propertyName)
End Function

Public Function GetObjectProperty(ByVal JsonObject As Object, ByVal propertyName As String) As Object
    Set GetObjectProperty = ScriptEngine.Run("getProperty", JsonObject, propertyName)
End Function

Public Function GetKeys(ByVal JsonObject As Object) As String()
    Dim Length As Integer
    Dim KeysArray() As String
    Dim KeysObject As Object
    Dim Index As Integer
    Dim Key As Variant

    Set KeysObject = ScriptEngine.Run("getKeys", JsonObject)
    Length = GetProperty(KeysObject, "length")
    ReDim KeysArray(Length - 1)
    Index = 0
    For Each Key In KeysObject
        KeysArray(Index) = Key
        Index = Index + 1
    Next
    GetKeys = KeysArray
End Function


Public Sub TestJsonAccess()
    Dim JsonString As String
    Dim JsonObject As Object
    Dim Keys() As String
    Dim Value As Variant
    Dim j As Variant

    InitScriptEngine

    JsonString = "{""key1"": ""val1"", ""key2"": { ""key3"": ""val3"" } }"
    Set JsonObject = DecodeJsonString(CStr(JsonString))
    Keys = GetKeys(JsonObject)

    Value = GetProperty(JsonObject, "key1")
    Set Value = GetObjectProperty(JsonObject, "key2")
End Sub

几个注意事项:

  • 如果JScriptTypeInfo实例引用Javascript对象,For Each ... Next不管用。但是,如果它引用Javascript数组(请参见GetKeys)。
  • 只有在运行时才知道其名称的访问属性,请使用以下函数GetPropertyGetObjectProperty.
  • Javascript数组提供以下属性length 0 Item 0 1 Item 1等等。用VBA点表示法(jsonObject.property),只有长度属性是可访问的,并且只有当声明一个名为length所有小写字母。否则这个案子就不符合了,也找不到了。其他属性在VBA中无效。所以最好使用GetProperty功能。
  • 代码使用早期绑定。因此,必须添加对“Microsoft脚本控制1.0”的引用。
  • 你得调用InitScriptEngine在使用其他函数进行一些基本初始化之前,先进行一次。
用户回答回答于

下面是在VBA中解析JSON的另一种方法,该方法基于ScriptControlActiveX,没有外部库:

Sub JsonTest()

    Dim Dict, Temp, Text, Keys, Items

    ' Converting JSON string to appropriate nested dictionaries structure
    ' Dictionaries have numeric keys for JSON Arrays, and string keys for JSON Objects
    ' Returns Nothing in case of any JSON syntax issues
    Set Dict = GetJsonDict("{a:[[{stuff:'result'}]], b:''}")
    ' You can use For Each ... Next and For ... Next loops through keys and items
    Keys = Dict.Keys
    Items = Dict.Items

    ' Referring directly to the necessary property if sure, without any checks
    MsgBox Dict("a")(0)(0)("stuff")

    ' Auxiliary DrillDown() function
    ' Drilling down the structure, sequentially checking if each level exists
    Select Case False
    Case DrillDown(Dict, "a", Temp, "")
    Case DrillDown(Temp, 0, Temp, "")
    Case DrillDown(Temp, 0, Temp, "")
    Case DrillDown(Temp, "stuff", "", Text)
    Case Else
        ' Structure is consistent, requested value found
        MsgBox Text
    End Select

End Sub

Function GetJsonDict(JsonString As String)
    With CreateObject("ScriptControl")
        .Language = "JScript"
        .ExecuteStatement "function gettype(sample) {return {}.toString.call(sample).slice(8, -1)}"
        .ExecuteStatement "function evaljson(json, er) {try {var sample = eval('(' + json + ')'); var type = gettype(sample); if(type != 'Array' && type != 'Object') {return er;} else {return getdict(sample);}} catch(e) {return er;}}"
        .ExecuteStatement "function getdict(sample) {var type = gettype(sample); if(type != 'Array' && type != 'Object') return sample; var dict = new ActiveXObject('Scripting.Dictionary'); if(type == 'Array') {for(var key = 0; key < sample.length; key++) {dict.add(key, getdict(sample[key]));}} else {for(var key in sample) {dict.add(key, getdict(sample[key]));}} return dict;}"
        Set GetJsonDict = .Run("evaljson", JsonString, Nothing)
    End With
End Function

Function DrillDown(Source, Prop, Target, Value)
    Select Case False
    Case TypeName(Source) = "Dictionary"
    Case Source.exists(Prop)
    Case Else
        Select Case True
        Case TypeName(Source(Prop)) = "Dictionary"
            Set Target = Source(Prop)
            Value = Empty
        Case IsObject(Source(Prop))
            Set Value = Source(Prop)
            Set Target = Nothing
        Case Else
            Value = Source(Prop)
            Set Target = Nothing
        End Select
        DrillDown = True
        Exit Function
    End Select
    DrillDown = False
End Function

请注意,上述方法在某些情况下使系统易受攻击,因为它允许通过ActiveX直接访问恶意JS代码的驱动器(和其他东西)。让我们假设正在解析Web服务器响应JSON,如JsonString = "{a:(function(){(new ActiveXObject('Scripting.FileSystemObject')).CreateTextFile('C:\\Test.txt')})()}"...。在对其进行评估之后,将找到新创建的文件C:\Test.txt...。所以JSON解析ScriptControlActiveX不是一个好主意。

为了避免这种情况,我创建了基于RegEx的JSON解析器。对象{}由字典表示,从而可以使用字典的属性和方法:.Count.Exists().Item().Items.Keys。阵列[]是传统的基于零的VB数组,所以UBound()显示元素的数量。下面是一些使用示例的代码:

Option Explicit

Sub JsonTest()
    Dim strJsonString As String
    Dim varJson As Variant
    Dim strState As String
    Dim varItem As Variant

    ' parse JSON string to object
    ' root element can be the object {} or the array []
    strJsonString = "{""a"":[{}, 0, ""value"", [{""stuff"":""content""}]], b:null}"
    ParseJson strJsonString, varJson, strState

    ' checking the structure step by step
    Select Case False ' if any of the checks is False, the sequence is interrupted
        Case IsObject(varJson) ' if root JSON element is object {},
        Case varJson.Exists("a") ' having property a,
        Case IsArray(varJson("a")) ' which is array,
        Case UBound(varJson("a")) >= 3 ' having not less than 4 elements,
        Case IsArray(varJson("a")(3)) ' where forth element is array,
        Case UBound(varJson("a")(3)) = 0 ' having the only element,
        Case IsObject(varJson("a")(3)(0)) ' which is object,
        Case varJson("a")(3)(0).Exists("stuff") ' having property stuff,
        Case Else
            MsgBox "Check the structure step by step" & vbCrLf & varJson("a")(3)(0)("stuff") ' then show the value of the last one property.
    End Select

    ' direct access to the property if sure of structure
    MsgBox "Direct access to the property" & vbCrLf & varJson.Item("a")(3)(0).Item("stuff") ' content

    ' traversing each element in array
    For Each varItem In varJson("a")
        ' show the structure of the element
        MsgBox "The structure of the element:" & vbCrLf & BeautifyJson(varItem)
    Next

    ' show the full structure starting from root element
    MsgBox "The full structure starting from root element:" & vbCrLf & BeautifyJson(varJson)

End Sub

Sub BeautifyTest()
    ' put sourse JSON string to "desktop\source.json" file
    ' processed JSON will be saved to "desktop\result.json" file
    Dim strDesktop As String
    Dim strJsonString As String
    Dim varJson As Variant
    Dim strState As String
    Dim strResult As String
    Dim lngIndent As Long

    strDesktop = CreateObject("WScript.Shell").SpecialFolders.Item("Desktop")
    strJsonString = ReadTextFile(strDesktop & "\source.json", -2)
    ParseJson strJsonString, varJson, strState
    If strState <> "Error" Then
        strResult = BeautifyJson(varJson)
        WriteTextFile strResult, strDesktop & "\result.json", -1
    End If
    CreateObject("WScript.Shell").PopUp strState, 1, , 64
End Sub

Sub ParseJson(ByVal strContent As String, varJson As Variant, strState As String)
    ' strContent - source JSON string
    ' varJson - created object or array to be returned as result
    ' strState - Object|Array|Error depending on processing to be returned as state
    Dim objTokens As Object
    Dim objRegEx As Object
    Dim bMatched As Boolean

    Set objTokens = CreateObject("Scripting.Dictionary")
    Set objRegEx = CreateObject("VBScript.RegExp")
    With objRegEx
        ' specification http://www.json.org/
        .Global = True
        .MultiLine = True
        .IgnoreCase = True
        .Pattern = """(?:\\""|[^""])*""(?=\s*(?:,|\:|\]|\}))"
        Tokenize objTokens, objRegEx, strContent, bMatched, "str"
        .Pattern = "(?:[+-])?(?:\d+\.\d*|\.\d+|\d+)e(?:[+-])?\d+(?=\s*(?:,|\]|\}))"
        Tokenize objTokens, objRegEx, strContent, bMatched, "num"
        .Pattern = "(?:[+-])?(?:\d+\.\d*|\.\d+|\d+)(?=\s*(?:,|\]|\}))"
        Tokenize objTokens, objRegEx, strContent, bMatched, "num"
        .Pattern = "\b(?:true|false|null)(?=\s*(?:,|\]|\}))"
        Tokenize objTokens, objRegEx, strContent, bMatched, "cst"
        .Pattern = "\b[A-Za-z_]\w*(?=\s*\:)" ' unspecified name without quotes
        Tokenize objTokens, objRegEx, strContent, bMatched, "nam"
        .Pattern = "\s"
        strContent = .Replace(strContent, "")
        .MultiLine = False
        Do
            bMatched = False
            .Pattern = "<\d+(?:str|nam)>\:<\d+(?:str|num|obj|arr|cst)>"
            Tokenize objTokens, objRegEx, strContent, bMatched, "prp"
            .Pattern = "\{(?:<\d+prp>(?:,<\d+prp>)*)?\}"
            Tokenize objTokens, objRegEx, strContent, bMatched, "obj"
            .Pattern = "\[(?:<\d+(?:str|num|obj|arr|cst)>(?:,<\d+(?:str|num|obj|arr|cst)>)*)?\]"
            Tokenize objTokens, objRegEx, strContent, bMatched, "arr"
        Loop While bMatched
        .Pattern = "^<\d+(?:obj|arr)>$" ' unspecified top level array
        If Not (.Test(strContent) And objTokens.Exists(strContent)) Then
            varJson = Null
            strState = "Error"
        Else
            Retrieve objTokens, objRegEx, strContent, varJson
            strState = IIf(IsObject(varJson), "Object", "Array")
        End If
    End With
End Sub

Sub Tokenize(objTokens, objRegEx, strContent, bMatched, strType)
    Dim strKey As String
    Dim strRes As String
    Dim lngCopyIndex As Long
    Dim objMatch As Object

    strRes = ""
    lngCopyIndex = 1
    With objRegEx
        For Each objMatch In .Execute(strContent)
            strKey = "<" & objTokens.Count & strType & ">"
            bMatched = True
            With objMatch
                objTokens(strKey) = .Value
                strRes = strRes & Mid(strContent, lngCopyIndex, .FirstIndex - lngCopyIndex + 1) & strKey
                lngCopyIndex = .FirstIndex + .Length + 1
            End With
        Next
        strContent = strRes & Mid(strContent, lngCopyIndex, Len(strContent) - lngCopyIndex + 1)
    End With
End Sub

Sub Retrieve(objTokens, objRegEx, strTokenKey, varTransfer)
    Dim strContent As String
    Dim strType As String
    Dim objMatches As Object
    Dim objMatch As Object
    Dim strName As String
    Dim varValue As Variant
    Dim objArrayElts As Object

    strType = Left(Right(strTokenKey, 4), 3)
    strContent = objTokens(strTokenKey)
    With objRegEx
        .Global = True
        Select Case strType
            Case "obj"
                .Pattern = "<\d+\w{3}>"
                Set objMatches = .Execute(strContent)
                Set varTransfer = CreateObject("Scripting.Dictionary")
                For Each objMatch In objMatches
                    Retrieve objTokens, objRegEx, objMatch.Value, varTransfer
                Next
            Case "prp"
                .Pattern = "<\d+\w{3}>"
                Set objMatches = .Execute(strContent)

                Retrieve objTokens, objRegEx, objMatches(0).Value, strName
                Retrieve objTokens, objRegEx, objMatches(1).Value, varValue
                If IsObject(varValue) Then
                    Set varTransfer(strName) = varValue
                Else
                    varTransfer(strName) = varValue
                End If
            Case "arr"
                .Pattern = "<\d+\w{3}>"
                Set objMatches = .Execute(strContent)
                Set objArrayElts = CreateObject("Scripting.Dictionary")
                For Each objMatch In objMatches
                    Retrieve objTokens, objRegEx, objMatch.Value, varValue
                    If IsObject(varValue) Then
                        Set objArrayElts(objArrayElts.Count) = varValue
                    Else
                        objArrayElts(objArrayElts.Count) = varValue
                    End If
                    varTransfer = objArrayElts.Items
                Next
            Case "nam"
                varTransfer = strContent
            Case "str"
                varTransfer = Mid(strContent, 2, Len(strContent) - 2)
                varTransfer = Replace(varTransfer, "\""", """")
                varTransfer = Replace(varTransfer, "\\", "\")
                varTransfer = Replace(varTransfer, "\/", "/")
                varTransfer = Replace(varTransfer, "\b", Chr(8))
                varTransfer = Replace(varTransfer, "\f", Chr(12))
                varTransfer = Replace(varTransfer, "\n", vbLf)
                varTransfer = Replace(varTransfer, "\r", vbCr)
                varTransfer = Replace(varTransfer, "\t", vbTab)
                .Global = False
                .Pattern = "\\u[0-9a-fA-F]{4}"
                Do While .Test(varTransfer)
                    varTransfer = .Replace(varTransfer, ChrW(("&H" & Right(.Execute(varTransfer)(0).Value, 4)) * 1))
                Loop
            Case "num"
                varTransfer = Evaluate(strContent)
            Case "cst"
                Select Case LCase(strContent)
                    Case "true"
                        varTransfer = True
                    Case "false"
                        varTransfer = False
                    Case "null"
                        varTransfer = Null
                End Select
        End Select
    End With
End Sub

Function BeautifyJson(varJson As Variant) As String
    Dim strResult As String
    Dim lngIndent As Long
    BeautifyJson = ""
    lngIndent = 0
    BeautyTraverse BeautifyJson, lngIndent, varJson, vbTab, 1
End Function

Sub BeautyTraverse(strResult As String, lngIndent As Long, varElement As Variant, strIndent As String, lngStep As Long)
    Dim arrKeys() As Variant
    Dim lngIndex As Long
    Dim strTemp As String

    Select Case VarType(varElement)
        Case vbObject
            If varElement.Count = 0 Then
                strResult = strResult & "{}"
            Else
                strResult = strResult & "{" & vbCrLf
                lngIndent = lngIndent + lngStep
                arrKeys = varElement.Keys
                For lngIndex = 0 To UBound(arrKeys)
                    strResult = strResult & String(lngIndent, strIndent) & """" & arrKeys(lngIndex) & """" & ": "
                    BeautyTraverse strResult, lngIndent, varElement(arrKeys(lngIndex)), strIndent, lngStep
                    If Not (lngIndex = UBound(arrKeys)) Then strResult = strResult & ","
                    strResult = strResult & vbCrLf
                Next
                lngIndent = lngIndent - lngStep
                strResult = strResult & String(lngIndent, strIndent) & "}"
            End If
        Case Is >= vbArray
            If UBound(varElement) = -1 Then
                strResult = strResult & "[]"
            Else
                strResult = strResult & "[" & vbCrLf
                lngIndent = lngIndent + lngStep
                For lngIndex = 0 To UBound(varElement)
                    strResult = strResult & String(lngIndent, strIndent)
                    BeautyTraverse strResult, lngIndent, varElement(lngIndex), strIndent, lngStep
                    If Not (lngIndex = UBound(varElement)) Then strResult = strResult & ","
                    strResult = strResult & vbCrLf
                Next
                lngIndent = lngIndent - lngStep
                strResult = strResult & String(lngIndent, strIndent) & "]"
            End If
        Case vbInteger, vbLong, vbSingle, vbDouble
            strResult = strResult & varElement
        Case vbNull
            strResult = strResult & "Null"
        Case vbBoolean
            strResult = strResult & IIf(varElement, "True", "False")
        Case Else
            strTemp = Replace(varElement, "\""", """")
            strTemp = Replace(strTemp, "\", "\\")
            strTemp = Replace(strTemp, "/", "\/")
            strTemp = Replace(strTemp, Chr(8), "\b")
            strTemp = Replace(strTemp, Chr(12), "\f")
            strTemp = Replace(strTemp, vbLf, "\n")
            strTemp = Replace(strTemp, vbCr, "\r")
            strTemp = Replace(strTemp, vbTab, "\t")
            strResult = strResult & """" & strTemp & """"
    End Select

End Sub

Function ReadTextFile(strPath As String, lngFormat As Long) As String
    ' lngFormat -2 - System default, -1 - Unicode, 0 - ASCII
    With CreateObject("Scripting.FileSystemObject").OpenTextFile(strPath, 1, False, lngFormat)
        ReadTextFile = ""
        If Not .AtEndOfStream Then ReadTextFile = .ReadAll
        .Close
    End With
End Function

Sub WriteTextFile(strContent As String, strPath As String, lngFormat As Long)
    With CreateObject("Scripting.FileSystemObject").OpenTextFile(strPath, 2, True, lngFormat)
        .Write (strContent)
        .Close
    End With
End Sub

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