json - Recorra cada tabla en la página web de javascrape con macro VBA

excel-vba web-scraping

Question

Estoy tratando de romper múltiples tablas de un sitio web. Hasta ahora, he construido una macro VBA de Excel para hacer esto. También descubrí cómo obtener todos los datos cuando están en varias páginas del sitio web. Por ejemplo, si tengo 1000 resultados pero se muestran 50 en cada página. El problema es que tengo las mismas 5 tablas en varias páginas porque cada tabla tiene 1000 resultados.

Mi código solo puede recorrer cada página para 1 tabla. También tengo un código escrito para tomar cada tabla, pero no puedo entender cómo hacerlo para cada uno de los 50 resultados de búsqueda (cada página).

¿Cómo puedo recorrer varias tablas y hacer clic en la página siguiente en el proceso para capturar todos los datos?

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

Hay un ejemplo que muestra cómo se pueden recuperar los datos del sitio web mediante el análisis XHR y JSON. Consta de varios pasos.

1. Recuperar los datos.

Investigué un poco con los XHR usando la pestaña Red de herramientas de desarrollador de Chrome. La información más relevante que encontré es la cadena JSON devuelta por GET XHR de http://www.etf.com/etf-finder-channel-tag/Smart-Beta%20ETFs/-aum/50/50/1 después de hacer clic en botón de página:

La respuesta tiene la siguiente estructura para un elemento de una sola fila :

[
  {
    "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"
    }
  }
]

2. La propiedad "totalRows": 803 especifica el recuento total de filas. Entonces, para que la recuperación de datos sea lo más rápida posible, es mejor hacer la solicitud para obtener la primera fila. Como puede ver en la URL, hay ../-aum/50/50/.. tail, que señala el orden de clasificación, el artículo desde el que comenzar y el total de artículos para devolver. Por lo tanto, para obtener la única fila, debe ser http://www.etf.com/etf-finder-channel-tag/Smart-Beta%20ETFs/-aum/0/1/1

3. Parse recupera JSON, obtiene el número total de filas de la propiedad totalRows .

4. Haga otra solicitud para obtener toda la tabla.

5. Analiza toda la tabla JSON, conviértela en matriz 2D y salida. Puede realizar un procesamiento adicional con acceso directo a la matriz.

Para la tabla que se muestra a continuación:

La tabla resultante contiene 803 filas y encabezado con columnas de la siguiente manera:

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

Ponga el siguiente código en el módulo estándar del Proyecto VBA:

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

Cree un módulo estándar más, asígnele el nombre JSON y coloque el siguiente código, este código proporciona la funcionalidad de procesamiento JSON:

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