Question

我试图从网站上抓取多个表格。到目前为止，我已经构建了一个excel VBA宏来执行此操作。我还想出了如何在网站的多个页面上获取所有数据。例如，如果我有1000个结果，但每页显示50个。问题是我在多个页面上有相同的5个表，因为每个表有1000个结果。

我的代码只能遍历1个表的每个页面。我也有编写代码来抓取每个表，但我无法弄清楚如何为50个搜索结果（每个页面）中的每一个执行此操作。

如何循环遍历多个表并单击流程中的下一页以捕获所有数据？

Sub ETFDat()

    Dim IE As Object
    Dim i As Long
    Dim strText As String
    Dim jj As Long
    Dim hBody As Object
    Dim hTR As Object
    Dim hTD As Object
    Dim tb As Object
    Dim bb As Object
    Dim Tr As Object
    Dim Td As Object
    Dim ii As Long
    Dim doc As Object
    Dim hTable As Object
    Dim y As Long
    Dim z As Long
    Dim wb As Excel.Workbook
    Dim ws As Excel.Worksheet

    Set wb = Excel.ActiveWorkbook
    Set ws = wb.ActiveSheet
    Set IE = CreateObject("InternetExplorer.Application")
    IE.Visible = True
    y = 1   'Column A in Excel
    z = 1   'Row 1 in Excel
    Sheets("Fund Basics").Activate
    Cells.Select
    Selection.Clear

    IE.navigate "http://www.etf.com/channels/smart-beta-etfs/channels/smart-       beta-etfs?qt-tabs=0#qt-tabs" ', , , , "Content-Type: application/x-www-form-urlencoded" & vbCrLf
    Do While IE.busy: DoEvents: Loop
    Do While IE.ReadyState <> 4: DoEvents: Loop
    Set doc = IE.document
    Set hTable = doc.getElementsByTagName("table")    '.GetElementByID("tablePerformance")
    ii = 1
    Do While ii <= 17
        For Each tb In hTable
            Set hBody = tb.getElementsByTagName("tbody")
            For Each bb In hBody
                Set hTR = bb.getElementsByTagName("tr")
                For Each Tr In hTR
                    Set hTD = Tr.getElementsByTagName("td")
                    y = 1 ' Resets back to column A
                    For Each Td In hTD
                        ws.Cells(z, y).Value = Td.innerText
                        y = y + 1
                    Next Td
                    DoEvents
                    z = z + 1
                Next Tr
                Exit For
            Next bb
            Exit For
        Next tb
        With doc
            Set elems = .getElementsByTagName("a")
            For Each e In elems
                If (e.getAttribute("id") = "nextPage") Then
                    e.Click
                    Exit For
                End If
            Next e
        End With
        ii = ii + 1
        Application.Wait (Now + TimeValue("00:00:05"))
    Loop

    MsgBox "Done"

End Sub

Answer 1

有一个示例显示如何使用XHR和JSON解析从网站检索数据，它包含几个步骤。

检索数据。

我使用Chrome开发者工具网络标签了解了XHR。我找到的大多数相关数据是GET XHR在点击下一页按钮后从http://www.etf.com/etf-finder-channel-tag/Smart-Beta%20ETFs/-aum/50/50/1返回的JSON字符串：

响应具有以下结构for single row item：

[
  {
    "productId": 576,
    "fund": "iShares Russell 1000 Value ETF",
    "ticker": "IWD",
    "inceptionDate": "2000-05-22",
    "launchDate": "2000-05-22",
    "hasSegmentReport": "true",
    "genericReport": "false",
    "hasReport": "true",
    "fundsInSegment": 20,
    "economicDevelopment": "Developed Markets",
    "totalRows": 803,
    "fundBasics": {
      "issuer": "<a href='/channels/blackrock-etfs' alt='BlackRock'>BlackRock</a>",
      "expenseRatio": {
        "value": 20
      },
      "aum": {
        "value": 36957230250
      },
      "spreadPct": {
        "value": 0.000094
      },
      "segment": "Equity: U.S. - Large Cap Value"
    },
    "performance": {
      "priceTrAsOf": "2017-02-27",
      "priceTr1Mo": {
        "value": 0.031843
      },
      "priceTr3Mo": {
        "value": 0.070156
      },
      "priceTr1Yr": {
        "value": 0.281541
      },
      "priceTr3YrAnnualized": {
        "value": 0.099171
      },
      "priceTr5YrAnnualized": {
        "value": 0.13778
      },
      "priceTr10YrAnnualized": {
        "value": 0.061687
      }
    },
    "analysis": {
      "analystPick": null,
      "opportunitiesList": null,
      "letterGrade": "A",
      "efficiencyScore": 97.977103,
      "tradabilityScore": 99.260541,
      "fitScore": 84.915658,
      "leveragedFactor": null,
      "exposureReset": null,
      "avgDailyDollarVolume": 243848188.037378,
      "avgDailyShareVolume": 2148400.688889,
      "spread": {
        "value": 0.010636
      },
      "fundClosureRisk": "Low"
    },
    "fundamentals": {
      "dividendYield": {
        "value": 0.021543
      },
      "equity": {
        "pe": 27.529645,
        "pb": 1.964124
      },
      "fixedIncome": {
        "duration": null,
        "creditQuality": null,
        "ytm": {
          "value": null
        }
      }
    },
    "classification": {
      "assetClass": "Equity",
      "strategy": "Value",
      "region": "North America",
      "geography": "U.S.",
      "category": "Size and Style",
      "focus": "Large Cap",
      "niche": "Value",
      "inverse": "false",
      "leveraged": "false",
      "etn": "false",
      "selectionCriteria": "Multi-Factor",
      "weightingScheme": "Multi-Factor",
      "activePerSec": "false",
      "underlyingIndex": "Russell 1000 Value Index",
      "indexProvider": "Russell",
      "brand": "iShares"
    },
    "tax": {
      "legalStructure": "Open-Ended Fund",
      "maxLtCapitalGainsRate": 20,
      "maxStCapitalGainsRate": 39.6,
      "taxReporting": "1099"
    }
  }
]

属性"totalRows": 803指定总行数。因此，为了尽可能快地进行数据检索，最好使请求获得第一行。正如您在URL中看到的那样，有../-aum/50/50/..尾部，它指向排序顺序，要开始的项目以及要返回的总项目。因此，要获得唯一的行，它应该是http://www.etf.com/etf-finder-channel-tag/Smart-Beta%20ETFs/-aum/0/1/1
解析检索到的JSON，从totalRows属性中获取总行数。
再提出一个请求来获取整个表格。
解析整个表JSON，将其转换为2d数组并输出。您可以通过直接访问阵列来执行进一步处理。

如下表所示：

结果表包含803行和带有列的标题，如下所示：

productId
fund
ticker
inceptionDate
launchDate
hasSegmentReport
genericReport
hasReport
fundsInSegment
economicDevelopment
totalRows
fundBasics_issuer
fundBasics_expenseRatio_value
fundBasics_aum_value
fundBasics_spreadPct_value
fundBasics_segment
performance_priceTrAsOf
performance_priceTr1Mo_value
performance_priceTr3Mo_value
performance_priceTr1Yr_value
performance_priceTr3YrAnnualized_value
performance_priceTr5YrAnnualized_value
performance_priceTr10YrAnnualized_value
analysis_analystPick
analysis_opportunitiesList
analysis_letterGrade
analysis_efficiencyScore
analysis_tradabilityScore
analysis_fitScore
analysis_leveragedFactor
analysis_exposureReset
analysis_avgDailyDollarVolume
analysis_avgDailyShareVolume
analysis_spread_value
analysis_fundClosureRisk
fundamentals_dividendYield_value
fundamentals_equity_pe
fundamentals_equity_pb
fundamentals_fixedIncome_duration
fundamentals_fixedIncome_creditQuality
fundamentals_fixedIncome_ytm_value
classification_assetClass
classification_strategy
classification_region
classification_geography
classification_category
classification_focus
classification_niche
classification_inverse
classification_leveraged
classification_etn
classification_selectionCriteria
classification_weightingScheme
classification_activePerSec
classification_underlyingIndex
classification_indexProvider
classification_brand
tax_legalStructure
tax_maxLtCapitalGainsRate
tax_maxStCapitalGainsRate
tax_taxReporting

将以下代码放入VBA Project标准模块：

Option Explicit

Sub GetData()

    Dim sJSONString As String
    Dim vJSON As Variant
    Dim sState As String
    Dim lRowsQty As Long
    Dim aData()
    Dim aHeader()

    ' Download and parse the only first row to get total rows qty
    sJSONString = GetXHR("http://www.etf.com/etf-finder-channel-tag/Smart-Beta%20ETFs/-aum/0/1/1")
    JSON.Parse sJSONString, vJSON, sState
    lRowsQty = vJSON(0)("totalRows")
    ' Download and parse the entire data
    sJSONString = GetXHR("http://www.etf.com/etf-finder-channel-tag/Smart-Beta%20ETFs/-aum/0/" & lRowsQty & "/1")
    JSON.Parse sJSONString, vJSON, sState
    ' Convert JSON to 2d array
    JSON.ToArray vJSON, aData, aHeader
    ' Output
    With Sheets(1)
        .Cells.Delete
        OutputArray .Cells(1, 1), aHeader
        Output2DArray .Cells(2, 1), aData
        .Cells.Columns.AutoFit
    End With

End Sub

Function GetXHR(sURL As String) As String

    With CreateObject("MSXML2.XMLHTTP")
        .Open "GET", sURL, False
        .Send
        GetXHR = .responseText
    End With

End Function

Sub OutputArray(oDstRng As Range, aCells As Variant)

    With oDstRng
        .Parent.Select
        With .Resize( _
                1, _
                UBound(aCells) - LBound(aCells) + 1)
            .NumberFormat = "@"
            .Value = aCells
        End With
    End With

End Sub

Sub Output2DArray(oDstRng As Range, aCells As Variant)

    With oDstRng
        .Parent.Select
        With .Resize( _
                UBound(aCells, 1) - LBound(aCells, 1) + 1, _
                UBound(aCells, 2) - LBound(aCells, 2) + 1)
            .NumberFormat = "@"
            .Value = aCells
        End With
    End With

End Sub

再创建一个标准模块，将其命名为JSON并将下面的代码放入其中，此代码提供JSON处理功能：

Option Explicit

Private sBuffer As String
Private oTokens As Object
Private oRegEx As Object
Private bMatch As Boolean
Private oChunks As Object
Private oHeader As Object
Private aData() As Variant
Private i As Long

Sub Parse(ByVal sSample As String, vJSON As Variant, sState As String)

    ' Backus–Naur form JSON parser implementation based on RegEx
    ' Input:
    ' sSample - source JSON string
    ' Output:
    ' vJson - created object or array to be returned as result
    ' sState - string Object|Array|Error depending on processing

    sBuffer = sSample
    Set oTokens = CreateObject("Scripting.Dictionary")
    Set oRegEx = CreateObject("VBScript.RegExp")
    With oRegEx ' Patterns based on specification http://www.json.org/
        .Global = True
        .MultiLine = True
        .IgnoreCase = True ' Unspecified True, False, Null accepted
        .Pattern = "(?:'[^']*'|""(?:\\""|[^""])*"")(?=\s*[,\:\]\}])" ' Double-quoted string, unspecified quoted string
        Tokenize "s"
        .Pattern = "[+-]?(?:\d+\.\d*|\.\d+|\d+)(?:e[+-]?\d+)?(?=\s*[,\]\}])" ' Number, E notation number
        Tokenize "d"
        .Pattern = "\b(?:true|false|null)(?=\s*[,\]\}])" ' Constants true, false, null
        Tokenize "c"
        .Pattern = "\b[A-Za-z_]\w*(?=\s*\:)" ' Unspecified non-double-quoted property name accepted
        Tokenize "n"
        .Pattern = "\s+"
        sBuffer = .Replace(sBuffer, "") ' Remove unnecessary spaces
        .MultiLine = False
        Do
            bMatch = False
            .Pattern = "<\d+(?:[sn])>\:<\d+[codas]>" ' Object property structure
            Tokenize "p"
            .Pattern = "\{(?:<\d+p>(?:,<\d+p>)*)?\}" ' Object structure
            Tokenize "o"
            .Pattern = "\[(?:<\d+[codas]>(?:,<\d+[codas]>)*)?\]" ' Array structure
            Tokenize "a"
        Loop While bMatch
        .Pattern = "^<\d+[oa]>$" ' Top level object structure, unspecified array accepted
        If .Test(sBuffer) And oTokens.Exists(sBuffer) Then
            Retrieve sBuffer, vJSON
            sState = IIf(IsObject(vJSON), "Object", "Array")
        Else
            vJSON = Null
            sState = "Error"
        End If
    End With
    Set oTokens = Nothing
    Set oRegEx = Nothing

End Sub

Private Sub Tokenize(sType)

    Dim aContent() As String
    Dim lCopyIndex As Long
    Dim i As Long
    Dim sKey As String

    With oRegEx.Execute(sBuffer)
        If .Count = 0 Then Exit Sub
        ReDim aContent(0 To .Count - 1)
        lCopyIndex = 1
        For i = 0 To .Count - 1
            With .Item(i)
                sKey = "<" & oTokens.Count & sType & ">"
                oTokens(sKey) = .Value
                aContent(i) = Mid(sBuffer, lCopyIndex, .FirstIndex - lCopyIndex + 1) & sKey
                lCopyIndex = .FirstIndex + .Length + 1
            End With
        Next
    End With
    sBuffer = Join(aContent, "") & Mid(sBuffer, lCopyIndex, Len(sBuffer) - lCopyIndex + 1)
    bMatch = True

End Sub

Private Sub Retrieve(sTokenKey, vTransfer)

    Dim sTokenValue As String
    Dim sName As String
    Dim vValue As Variant
    Dim aTokens() As String
    Dim i As Long

    sTokenValue = oTokens(sTokenKey)
    With oRegEx
        .Global = True
        Select Case Left(Right(sTokenKey, 2), 1)
            Case "o"
                Set vTransfer = CreateObject("Scripting.Dictionary")
                aTokens = Split(sTokenValue, "<")
                For i = 1 To UBound(aTokens)
                    Retrieve "<" & Split(aTokens(i), ">", 2)(0) & ">", vTransfer
                Next
            Case "p"
                aTokens = Split(sTokenValue, "<", 4)
                Retrieve "<" & Split(aTokens(1), ">", 2)(0) & ">", sName
                Retrieve "<" & Split(aTokens(2), ">", 2)(0) & ">", vValue
                If IsObject(vValue) Then
                    Set vTransfer(sName) = vValue
                Else
                    vTransfer(sName) = vValue
                End If
            Case "a"
                aTokens = Split(sTokenValue, "<")
                If UBound(aTokens) = 0 Then
                    vTransfer = Array()
                Else
                    ReDim vTransfer(0 To UBound(aTokens) - 1)
                    For i = 1 To UBound(aTokens)
                        Retrieve "<" & Split(aTokens(i), ">", 2)(0) & ">", vValue
                        If IsObject(vValue) Then
                            Set vTransfer(i - 1) = vValue
                        Else
                            vTransfer(i - 1) = vValue
                        End If
                    Next
                End If
            Case "n"
                vTransfer = sTokenValue
            Case "s"
                vTransfer = Replace(Replace(Replace(Replace(Replace(Replace(Replace(Replace( _
                    Mid(sTokenValue, 2, Len(sTokenValue) - 2), _
                    "\""", """"), _
                    "\\", "\"), _
                    "\/", "/"), _
                    "\b", Chr(8)), _
                    "\f", Chr(12)), _
                    "\n", vbLf), _
                    "\r", vbCr), _
                    "\t", vbTab)
                .Global = False
                .Pattern = "\\u[0-9a-fA-F]{4}"
                Do While .Test(vTransfer)
                    vTransfer = .Replace(vTransfer, ChrW(("&H" & Right(.Execute(vTransfer)(0).Value, 4)) * 1))
                Loop
            Case "d"
                vTransfer = Evaluate(sTokenValue)
            Case "c"
                Select Case LCase(sTokenValue)
                    Case "true"
                        vTransfer = True
                    Case "false"
                        vTransfer = False
                    Case "null"
                        vTransfer = Null
                End Select
        End Select
    End With

End Sub

Function Serialize(vJSON As Variant) As String

    Set oChunks = CreateObject("Scripting.Dictionary")
    SerializeElement vJSON, ""
    Serialize = Join(oChunks.Items(), "")
    Set oChunks = Nothing

End Function

Private Sub SerializeElement(vElement As Variant, ByVal sIndent As String)

    Dim aKeys() As Variant
    Dim i As Long

    With oChunks
        Select Case VarType(vElement)
            Case vbObject
                If vElement.Count = 0 Then
                    .Item(.Count) = "{}"
                Else
                    .Item(.Count) = "{" & vbCrLf
                    aKeys = vElement.Keys
                    For i = 0 To UBound(aKeys)
                        .Item(.Count) = sIndent & vbTab & """" & aKeys(i) & """" & ": "
                        SerializeElement vElement(aKeys(i)), sIndent & vbTab
                        If Not (i = UBound(aKeys)) Then .Item(.Count) = ","
                        .Item(.Count) = vbCrLf
                    Next
                    .Item(.Count) = sIndent & "}"
                End If
            Case Is >= vbArray
                If UBound(vElement) = -1 Then
                    .Item(.Count) = "[]"
                Else
                    .Item(.Count) = "[" & vbCrLf
                    For i = 0 To UBound(vElement)
                        .Item(.Count) = sIndent & vbTab
                        SerializeElement vElement(i), sIndent & vbTab
                        If Not (i = UBound(vElement)) Then .Item(.Count) = "," 'sResult = sResult & ","
                        .Item(.Count) = vbCrLf
                    Next
                    .Item(.Count) = sIndent & "]"
                End If
            Case vbInteger, vbLong
                .Item(.Count) = vElement
            Case vbSingle, vbDouble
                .Item(.Count) = Replace(vElement, ",", ".")
            Case vbNull
                .Item(.Count) = "null"
            Case vbBoolean
                .Item(.Count) = IIf(vElement, "true", "false")
            Case Else
                .Item(.Count) = """" & _
                    Replace(Replace(Replace(Replace(Replace(Replace(Replace(Replace(vElement, _
                        "\", "\\"), _
                        """", "\"""), _
                        "/", "\/"), _
                        Chr(8), "\b"), _
                        Chr(12), "\f"), _
                        vbLf, "\n"), _
                        vbCr, "\r"), _
                        vbTab, "\t") & _
                    """"
        End Select
    End With

End Sub

Function ToString(vJSON As Variant) As String

    Select Case VarType(vJSON)
        Case vbObject, Is >= vbArray
            Set oChunks = CreateObject("Scripting.Dictionary")
            ToStringElement vJSON, ""
            oChunks.Remove 0
            ToString = Join(oChunks.Items(), "")
            Set oChunks = Nothing
        Case vbNull
            ToString = "Null"
        Case vbBoolean
            ToString = IIf(vJSON, "True", "False")
        Case Else
            ToString = CStr(vJSON)
    End Select

End Function

Private Sub ToStringElement(vElement As Variant, ByVal sIndent As String)

    Dim aKeys() As Variant
    Dim i As Long

    With oChunks
        Select Case VarType(vElement)
            Case vbObject
                If vElement.Count = 0 Then
                    .Item(.Count) = "''"
                Else
                    .Item(.Count) = vbCrLf
                    aKeys = vElement.Keys
                    For i = 0 To UBound(aKeys)
                        .Item(.Count) = sIndent & aKeys(i) & ": "
                        ToStringElement vElement(aKeys(i)), sIndent & vbTab
                        If Not (i = UBound(aKeys)) Then .Item(.Count) = vbCrLf
                    Next
                End If
            Case Is >= vbArray
                If UBound(vElement) = -1 Then
                    .Item(.Count) = "''"
                Else
                    .Item(.Count) = vbCrLf
                    For i = 0 To UBound(vElement)
                        .Item(.Count) = sIndent & i & ": "
                        ToStringElement vElement(i), sIndent & vbTab
                        If Not (i = UBound(vElement)) Then .Item(.Count) = vbCrLf
                    Next
                End If
            Case vbNull
                .Item(.Count) = "Null"
            Case vbBoolean
                .Item(.Count) = IIf(vElement, "True", "False")
            Case Else
                .Item(.Count) = CStr(vElement)
        End Select
    End With

End Sub

Sub ToArray(vJSON As Variant, aRows() As Variant, aHeader() As Variant)

    ' Input:
    ' vJSON - Array or Object which contains rows data
    ' Output:
    ' aData - 2d array representing JSON data
    ' aHeader - 1d array of property names

    Dim sName As Variant

    Set oHeader = CreateObject("Scripting.Dictionary")
    Select Case VarType(vJSON)
        Case vbObject
            If vJSON.Count > 0 Then
                ReDim aData(0 To vJSON.Count - 1, 0 To 0)
                oHeader("#") = 0
                i = 0
                For Each sName In vJSON
                    aData(i, 0) = "#" & sName
                    ToArrayElement vJSON(sName), ""
                    i = i + 1
                Next
            Else
                ReDim aData(0 To 0, 0 To 0)
            End If
        Case Is >= vbArray
            If UBound(vJSON) >= 0 Then
                ReDim aData(0 To UBound(vJSON), 0 To 0)
                For i = 0 To UBound(vJSON)
                    ToArrayElement vJSON(i), ""
                Next
            Else
                ReDim aData(0 To 0, 0 To 0)
            End If
        Case Else
            ReDim aData(0 To 0, 0 To 0)
            aData(0, 0) = ToString(vJSON)
    End Select
    aHeader = oHeader.Keys()
    Set oHeader = Nothing
    aRows = aData
    Erase aData

End Sub

Private Sub ToArrayElement(vElement As Variant, sFieldName As String)

    Dim sName As Variant
    Dim j As Long

    Select Case VarType(vElement)
        Case vbObject ' collection of objects
            For Each sName In vElement
                ToArrayElement vElement(sName), sFieldName & IIf(sFieldName = "", "", "_") & sName
            Next
        Case Is >= vbArray  ' collection of arrays
            For j = 0 To UBound(vElement)
                ToArrayElement vElement(j), sFieldName & IIf(sFieldName = "", "", "_") & "#" & j
            Next
        Case Else
            If Not oHeader.Exists(sFieldName) Then
                oHeader(sFieldName) = oHeader.Count
                If UBound(aData, 2) < oHeader.Count - 1 Then ReDim Preserve aData(0 To UBound(aData, 1), 0 To oHeader.Count - 1)
            End If
            j = oHeader(sFieldName)
            aData(i, j) = ToString(vElement)
    End Select

End Sub

使用VBA宏

1 个答案: