Submit or bypass form for a Web Query - html

Question

I'm trying to get dollar exchange rate from http://www4.bcb.gov.br/pec/taxas/port/ptaxnpesq.asp?id=txcotacao into a Excel spreadsheet.
I tried to paste as refreshable web query, however, the page opens one step earlier with a form, which has default inputs (that work for me) and then the query copies stuff from this page.
I tried to write a code to submit the form. I tried the .submit, .Click, .FireEvent and many other things I found on internet.
I tried to refer to the button by its name, class, tag, ...
<input title="Pesquisar" class="botao" onclick="limparVazio()" type="submit" value="Pesquisar">
I tried to trigger the form directly or bypass it
<form name="consultarBoletimForm" action="/ptax_internet/consultaBoletim.do?method=consultarBoletim" method="post">

Answer 1

You can use the bcb.gov.br Open Data Portal.
Send a request for a JSON response with the conversion rates from their Exchange rates – daily bulletins.
With the received response, amongst other methods, you can then:
Use the JSON Converter and set the convert the response into a JSON object and work with that;
Parse the response as a string with a regex to get the values
Looking at the results for today's rate on the site:
Input:
Output:
Result:
You can see USD 1 = 3,7048 BRL
① Using JSON object:
Example string to make request:
"https://olinda.bcb.gov.br/olinda/service/PTAX/version/v1/odata/ExchangeRatePeriod(moeda=#moeda,dataInicial=#dataInicial,dataFinalCotacao=#dataFinalCotacao)?%40moeda=%27" & TARGET_CURRENCY & "%27&%40dataInicial=%27" & START_DATE & "%27&%40dataFinalCotacao=%27" & END_DATE & "%27&%24format=json"
I include the start date, end date and currency in the string as well as specify the response format as JSON. I have selected the date to match the website view shown in the images above.
The JSON response is as follows:
I read the response into a string variable and then use JsonConverter.ParseJson(strJSON) to convert to a JSON object, stored in json variable. A quick inspection of the structure:
The begining "{" tells me that json is a dictionary.
I can also see that json("value") is a collection of dictionaries and that the value I am interested in, 3,7048 - remember from the website images above, is stored as "cotacaoCompra".
I can thus use the following script to access that value. The JSON response actually gives rates at 5 different times on that date in question. These are all printed out. The Fechamento (Closing) bulletin rate of 3,7048 we can see matches.
Code:
Option Explicit
Public Sub GetInfo()
Dim strURL As String, strJSON As String, item As Variant, http As Object, json As Object
Const TARGET_CURRENCY As String = "USD"
Const START_DATE As String = "06-13-2018"
Const END_DATE As String = "06-13-2018"
strURL = "https://olinda.bcb.gov.br/olinda/service/PTAX/version/v1/odata/ExchangeRatePeriod(moeda=#moeda,dataInicial=#dataInicial,dataFinalCotacao=#dataFinalCotacao)?%40moeda=%27" & TARGET_CURRENCY & "%27&%40dataInicial=%27" & START_DATE & "%27&%40dataFinalCotacao=%27" & END_DATE & "%27&%24format=json"
Set http = CreateObject("MSXML2.XMLHTTP")
http.Open "GET", strURL, False
http.send
strJSON = http.responseText
Set json = JsonConverter.ParseJson(strJSON)
For Each item In json("value")
Debug.Print "rate " & item("cotacaoCompra") & " at " & item("dataHoraCotacao")
Next item
End Sub
Script output:
Notes:
Requires JSONConverter bas added and VBE > Tools > References > Microsoft Scripting RunTime)
② Parsing the responseText with a regex to get the rates:
The regex I will use is
"cotacaoCompra":\d{1,}.\d{1,}
This looks for the literal string "cotacaoCompra":, followed by 1 or more numbers then a ".", then one of more numbers.
I then have to remove the string "cotacaoCompra": with a straight forward replace. Ideally, I would just extract the numbers with "(?<=""cotacaoCompra"":)\d{1,}.\d{1,}"; basically, that says after, but not including "cotacaoCompra":. But that doesn't appear to be supported.
With that in mind the script to get the rates with regex:
Code:
Public Sub GetInfo2()
Dim strURL As String, strJSON As String, item As Variant, http As Object, json As Object
Const TARGET_CURRENCY As String = "USD"
Const START_DATE As String = "06-13-2018"
Const END_DATE As String = "06-13-2018"
strURL = "https://olinda.bcb.gov.br/olinda/service/PTAX/version/v1/odata/ExchangeRatePeriod(moeda=#moeda,dataInicial=#dataInicial,dataFinalCotacao=#dataFinalCotacao)?%40moeda=%27" & TARGET_CURRENCY & "%27&%40dataInicial=%27" & START_DATE & "%27&%40dataFinalCotacao=%27" & END_DATE & "%27&%24format=json"
Set http = CreateObject("MSXML2.XMLHTTP")
http.Open "GET", strURL, False
http.send
strJSON = http.responseText
Dim Matches As Object
With CreateObject("VBScript.RegExp")
.Global = True
.MultiLine = True
.IgnoreCase = False
.Pattern = """cotacaoCompra"":\d{1,}.\d{1,}" 'The pattern I really wanted, "(?<=""cotacaoCompra"":)\d{1,}.\d{1,}", doesn't appear to be supported
If Not .test(strJSON) Then Exit Sub
Set Matches = .Execute(strJSON)
Dim match As Object
For Each match In Matches
Debug.Print Replace(match, """cotacaoCompra"":", vbNullString)
Next
End With
End Sub