Bulk Renaming column in PQ with a pattern

[smpa01]

@AlexisOlson  @ImkeF 

whenever I pull data from SSAS tables, they come as like this. 

I want to bulk rename the colNames in a way that returns the value inside parenthesis

My end goal is this

I tried this. Is it the best-optimized way to do this, I want the best optimization possible for a large tbl.

CT = Table.TransformColumnTypes(
    src,
    {{"db[colA]", Int64.Type}, {"db[colB]", Int64.Type}, {"db[colC]", Int64.Type}}
  ),
  Change = Table.TransformColumnNames(CT, each Text.Replace(Text.Split(_, "["){1}, "]", ""))

let
  src=Table.FromRows(
    Json.Document(
      Binary.Decompress(
        Binary.FromText("i45WMlTSUTICYmOlWJ1oJRMgyxSIzZRiYwE=", BinaryEncoding.Base64),
        Compression.Deflate
      )
    ),
    let
      _t = ((type nullable text) meta [Serialized.Text = true])
    in
      type table [#"db[colA]" = _t, #"db[colB]" = _t, #"db[colC]" = _t]
  ),
  CT = Table.TransformColumnTypes(
    src,
    {{"db[colA]", Int64.Type}, {"db[colB]", Int64.Type}, {"db[colC]", Int64.Type}}
  ),
  Change = Table.TransformColumnNames(CT, each Text.Replace(Text.Split(_, "["){1}, "]", ""))
in
  Change

Thank you in advance.

[mahoneypat · Accepted solution]

I would try this way first, in a single rename columns step using List.Zip and List.Transform.

let
  src=Table.FromRows(
    Json.Document(
      Binary.Decompress(
        Binary.FromText("i45WMlTSUTICYmOlWJ1oJRMgyxSIzZRiYwE=", BinaryEncoding.Base64),
        Compression.Deflate
      )
    ),
    let
      _t = ((type nullable text) meta [Serialized.Text = true])
    in
      type table [#"db[colA]" = _t, #"db[colB]" = _t, #"db[colC]" = _t]
  ),
    #"Renamed Columns" = Table.RenameColumns(src,List.Zip({Table.ColumnNames(src), List.Transform(Table.ColumnNames(src), each Text.BetweenDelimiters(_, "[", "]"))}))
in
    #"Renamed Columns"

Pat

[smpa01]

Thanks @mahoneypat  @AlexisOlson  

I tested out each of our Query plan

Me, @AlexisOlson and @mahoneypat  has exactly the same Query Plan as the following despite using different techniques. I don't know how?

I will use this

Table.TransformColumnNames(src, each Text.BetweenDelimiters(_, "[", "]"))

[mahoneypat]

They actually generate the same list of lists, but I would go with the one from @AlexisOlson too. That approach is more elegant.

Pat

[AlexisOlson · Accepted solution]

I have a custom function ShortenColumnNames that I run on all of these:

(Source as table) as table =>
let
    ColNamesList = Table.ColumnNames(Source),
    Transform = Table.RenameColumns(Source,
        List.Transform(ColNamesList, each {_, Text.BetweenDelimiters(_, "[", "]")}))
in
    Transform

 So each of my SSAS queries starts like this (I keep the DAX queries separately):

let
    Source = AnalysisServices.Database(Workspace, Dataset, [Query=DAXQuery, Implementation="2.0"]),
    RenameCols = ShortenColumnNames(Source),
    [...etc...]

[mahoneypat · Accepted solution]

I would try this way first, in a single rename columns step using List.Zip and List.Transform.

let
  src=Table.FromRows(
    Json.Document(
      Binary.Decompress(
        Binary.FromText("i45WMlTSUTICYmOlWJ1oJRMgyxSIzZRiYwE=", BinaryEncoding.Base64),
        Compression.Deflate
      )
    ),
    let
      _t = ((type nullable text) meta [Serialized.Text = true])
    in
      type table [#"db[colA]" = _t, #"db[colB]" = _t, #"db[colC]" = _t]
  ),
    #"Renamed Columns" = Table.RenameColumns(src,List.Zip({Table.ColumnNames(src), List.Transform(Table.ColumnNames(src), each Text.BetweenDelimiters(_, "[", "]"))}))
in
    #"Renamed Columns"

Pat