What does this M function do ?

[bboy0009]

Hi guys,

As mentionned in the title, I would like to understand what this function below does 

let
    Yesterday = "/received_payments_report_"&
    Date.ToText( DateTime.Date( Date.AddDays(DateTime.LocalNow(), -1)) , "yyyy_MM_dd")&".csv",
  getUserData = (loops as number,  optional data_list as list ) =>
let
  Query = Web.Contents(
      "https://URL of the data source/", [RelativePath= Record.Field(_MerchantAccountHelper{loops}, "Merchant Account Name") & Yesterday]
      
    ),
  Results = {Csv.Document(Query, [Delimiter = ",", Columns = 88, QuoteStyle = QuoteStyle.None])},

    currentLoop = loops + 1,
    currentResults = 
        if data_list is null then Results 
        else List.Combine({data_list, Results}) ,
    output = 
        if loops > Table.RowCount(_MerchantAccountHelper) then currentResults 
        else @getUserData(currentLoop,  currentResults ) 
in
    output
in
  getUserData

How the value of currentLoop and currentResults have been initiated ? I'm curious about it because I don't see something like currentLoop = 0 and loops doesn't also have a value. Same thing for currentResults. 

Why is there an IF loop > Table.RowCount.... ?

Thank you in advance !

[m_dekorte]

Hi @bboy0009 

This query returns a function (value) that is designed to fetch CSV reports from a web source. getUserData has two parameters to fetch data, loops as number, and optionally appends it's restult to a list of data, optional data_list as list,  That answers your fist question, the value of loop in currentLoop is determined by the user's first argument value when this function is invoked.

The if loops > Table.RowCount determines whether to continue looping or to return the final results. If the loop counter exceeds the number of merchant accounts, it returns the currentResults, ending the looping process. Otherwise, it recursively calls getUserData incrementing the loop counter +1, continuing the looping process to fetch and combine a new set of results to the previous ones.

I hope this is helpful