Excel VBA Macro: Scraping data from site table that spans multiple pages - vba

Question

Thanks in advance for the help. I'm running Windows 8.1, I have the latest IE / Chrome browsers, and the latest Excel. I'm trying to write an Excel Macro that pulls data from StackOverflow (https://stackoverflow.com/tags). Specifically, I'm trying to pull the date (that the macro is run), the tag names, the # of tags, and the brief description of what the tag is. I have it working for the first page of the table, but not for the rest (there are 1132 pages at the moment). Right now, it overwrites the data everytime I run the macro, and I'm not sure how to make it look for the next empty cell before running.. Lastly, I'm trying to make it run automatically once per week.
I'd much appreciate any help here. Problems are:
Pulling data from the web table beyond the first page
Making it scrape data to the next empty row rather than overwriting
Making the Macro run automatically once per week
Code (so far) is below. Thanks!
Enum READYSTATE
READYSTATE_UNINITIALIZED = 0
READYSTATE_LOADING = 1
READYSTATE_LOADED = 2
READYSTATE_INTERACTIVE = 3
READYSTATE_COMPLETE = 4
End Enum
Sub ImportStackOverflowData()
'to refer to the running copy of Internet Explorer
Dim ie As InternetExplorer
'to refer to the HTML document returned
Dim html As HTMLDocument
'open Internet Explorer in memory, and go to website
Set ie = New InternetExplorer
ie.Visible = False
ie.navigate "http://stackoverflow.com/tags"
'Wait until IE is done loading page
Do While ie.READYSTATE <> READYSTATE_COMPLETE
Application.StatusBar = "Trying to go to StackOverflow ..."
DoEvents
Loop
'show text of HTML document returned
Set html = ie.document
'close down IE and reset status bar
Set ie = Nothing
Application.StatusBar = ""
'clear old data out and put titles in
'Cells.Clear
'put heading across the top of row 3
Range("A3").Value = "Date Pulled"
Range("B3").Value = "Keyword"
Range("C3").Value = "# Of Tags"
'Range("C3").Value = "Asked This Week"
Range("D3").Value = "Description"
Dim TagList As IHTMLElement
Dim Tags As IHTMLElementCollection
Dim Tag As IHTMLElement
Dim RowNumber As Long
Dim TagFields As IHTMLElementCollection
Dim TagField As IHTMLElement
Dim Keyword As String
Dim NumberOfTags As String
'Dim AskedThisWeek As String
Dim TagDescription As String
'Dim QuestionFieldLinks As IHTMLElementCollection
Dim TodaysDate As Date
Set TagList = html.getElementById("tags-browser")
Set Tags = html.getElementsByClassName("tag-cell")
RowNumber = 4
For Each Tag In Tags
'if this is the tag containing the details, process it
If Tag.className = "tag-cell" Then
'get a list of all of the parts of this question,
'and loop over them
Set TagFields = Tag.all
For Each TagField In TagFields
'if this is the keyword, store it
If TagField.className = "post-tag" Then
'store the text value
Keyword = TagField.innerText
Cells(RowNumber, 2).Value = TagField.innerText
End If
If TagField.className = "item-multiplier-count" Then
'store the integer for number of tags
NumberOfTags = TagField.innerText
'NumberOfTags = Replace(NumberOfTags, "x", "")
Cells(RowNumber, 3).Value = Trim(NumberOfTags)
End If
If TagField.className = "excerpt" Then
Description = TagField.innerText
Cells(RowNumber, 4).Value = TagField.innerText
End If
TodaysDate = Format(Now, "MM/dd/yy")
Cells(RowNumber, 1).Value = TodaysDate
Next TagField
'go on to next row of worksheet
RowNumber = RowNumber + 1
End If
Next
Set html = Nothing
'do some final formatting
Range("A3").CurrentRegion.WrapText = False
Range("A3").CurrentRegion.EntireColumn.AutoFit
Range("A1:C1").EntireColumn.HorizontalAlignment = xlCenter
Range("A1:D1").Merge
Range("A1").Value = "StackOverflow Tag Trends"
Range("A1").Font.Bold = True
Application.StatusBar = ""
MsgBox "Done!"
End Sub

Answer 1

There's no need to scrape Stack Overflow when they make the underlying data available to you through things like the Data Explorer. Using this query in the Data Explorer should get you the results you need:
select t.TagName, t.Count, p.Body
from Tags t inner join Posts p
on t.ExcerptPostId = p.Id
order by t.count desc;
The permalink to that query is here and the "Download CSV" option which appears after the query runs is probably the easiest way to get the data into Excel. If you wanted to automate that part of things, the direct link to the CSV download of results is here

Answer 2

You can improve this to parse out exact elements but it loops all the pages and grabs all the tag info (everything next to a tag)
Option Explicit
Public Sub ImportStackOverflowData()
Dim ie As New InternetExplorer, html As HTMLDocument
Application.ScreenUpdating = False
With ie
.Visible = True
.navigate "https://stackoverflow.com/tags"
While .Busy Or .READYSTATE < 4: DoEvents: Wend
Set html = .document
Dim numPages As Long, i As Long, info As Object, item As Object, counter As Long
numPages = html.querySelector(".page-numbers.dots ~ a").innerText
For i = 1 To 2 ' numPages ''<==1 to 2 for testing; use to numPages
DoEvents
Set info = html.getElementById("tags_list")
For Each item In info.getElementsByClassName("grid-layout--cell tag-cell")
counter = counter + 1
Cells(counter, 1) = item.innerText
Next item
html.querySelector(".page-numbers.next").Click
While .Busy Or .READYSTATE < 4: DoEvents: Wend
Set html = .document
Next i
Application.ScreenUpdating = True
.Quit '<== Remember to quit application
End With
End Sub

Answer 3

I'm not making use of the DOM, but I find it very easy to get around just searching between known tags. If ever the expressions you are looking for are too common just tweak the code a bit so that it looks for a string after a string).
An example:
Public Sub ZipLookUp()
Dim URL As String, xmlHTTP As Object, html As Object, htmlResponse As String
Dim SStr As String, EStr As String, EndS As Integer, StartS As Integer
Dim Zip4Digit As String
URL = "https://tools.usps.com/go/ZipLookupResultsAction!input.action?resultMode=1&companyName=&address1=1642+Harmon+Street&address2=&city=Berkeley&state=CA&urbanCode=&postalCode=&zip=94703"
Set xmlHTTP = CreateObject("MSXML2.XMLHTTP")
xmlHTTP.Open "GET", URL, False
On Error GoTo NoConnect
xmlHTTP.send
On Error GoTo 0
Set html = CreateObject("htmlfile")
htmlResponse = xmlHTTP.ResponseText
If htmlResponse = Null Then
MsgBox ("Aborted Run - HTML response was null")
Application.ScreenUpdating = True
GoTo End_Prog
End If
'Searching for a string within 2 strings
SStr = "<span class=""address1 range"">" ' first string
EStr = "</span><br />" ' second string
StartS = InStr(1, htmlResponse, SStr, vbTextCompare) + Len(SStr)
EndS = InStr(StartS, htmlResponse, EStr, vbTextCompare)
Zip4Digit = Left(Mid(htmlResponse, StartS, EndS - StartS), 4)
MsgBox Zip4Digit
GoTo End_Prog
NoConnect:
If Err = -2147467259 Or Err = -2146697211 Then MsgBox "Error - No Connection": GoTo End_Prog 'MsgBox Err & ": " & Error(Err)
End_Prog:
End Sub