Load files from folder with a custom query with power BI

Question

I am trying to load csv files from a folder but I need to apply several custom steps to each file, including dropping the PromoteHeaders default.

I have a custom query that can load a single file successfully. How do I turn it into a query that loads all files in a folder?

By default, File.folder's "promoteHeaders" messes up my data because of a missing column name (which my custom query fixes).

Answer 1

The easiest way to create a function that reads a specific template of file is to actually do it. Just create the M to read it and by right click on the entity transform it to a function.

After that is really simple to transform your M so it uses parameters.

You can create a blank query and replace the code with this on as an example, customize with more steps to deal with your file requirements.

= (myFile) => let
        Source = Csv.Document(myFile,[Delimiter=",", Columns=33, Encoding=1252, QuoteStyle=QuoteStyle.None])
    in
        Source

And then Invoke Custom Function for each file with the content as the parameter.