trying to extract file type from file path

Hi Anonymous - use this formula:

Text.AfterDelimiter([Path], ".", {0, RelativePosition.FromEnd})

It will find the first period from the right (end) of the path, then give you all text after that period. Full M code:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("JclBCoAgEADAr4j33NondKtjHSPEYoWNckNF6PcZwdxmWbTzngPnB2Y+C0Vwe+ZClkOhlCUmuCkmCXC5G4YA2GILHX7+SLaXTU1GjUL226bDyhz19Lq+", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Path = _t]),
    #"Added Custom" = Table.AddColumn(Source, "Extension", each Text.AfterDelimiter([Path], ".", {0, RelativePosition.FromEnd}))
in
    #"Added Custom"

How to use M code provided in a blank query:
1) In Power Query, select New Source, then Blank Query
2) On the Home ribbon, select "Advanced Editor" button
3) Remove everything you see, then paste the M code I've given you in that box.
4) Press Done
5) See this article if you need help using this M code in your model.