Powerquery: how to iterate/loop parameters list? - list

Question

How to substitute code below with compact loop?
let
ParametersList = {"CustomerID","FirstName","LastName"},
Source1 = fnCheckId(srcTbl , ParametersList{0}),
Source2 = fnCheckId(Source1, ParametersList{1}),
Source3 = fnCheckId(Source2, ParametersList{2}),
Result = Source3
in
Result
Looping Problems:
It should loop ParametersList
current loop output table should work as input Table for next loop
SIMPLIFIED EXAMPLE DETAILS (Source File):
fnCheckId function example (in real business case much more complex):
(tbl as table, clm as text)=>
let
//tbl = srcTbl, clm = "FirstName",
#"Added Custom" = Table.AddColumn(tbl,"QA "&clm, each if Text.Length(Record.Field(_, clm))>3 then "Ok" else "Nok")
in
#"Added Custom"
Source Table:
Table.FromRows(
{
{1, "Bob", "Smith", "123-4567"},
{2, "Jim", "Brown", "987-6543"},
{3, "Paul", "Wick", "543-7890"}
},
{"CustomerID", "FirstName", "LastName", "Phone"}
)
Estimated Result Table:

Answer 1

With original function, how about
let srcTbl = Table.FromRows(
{
{1, "Bob", "Smith", "123-4567"},
{2, "Jim", "Brown", "987-6543"},
{3, "Paul", "Wick", "543-7890"}
},
{"CustomerID", "FirstName", "LastName", "Phone"}
),
List = {"CustomerID", "FirstName", "LastName"},
#"Unpivoted Only Selected Columns" = Table.Unpivot(srcTbl, List, "Attribute", "Value"),
Source1 = fnCheckId(#"Unpivoted Only Selected Columns","Value"),
#"Removed Columns" = Table.RemoveColumns(Source1,{"Value"}),
#"Renamed Columns" = Table.RenameColumns(#"Removed Columns",{{"QA Value", "Value"}}),
#"Change Title" = Table.TransformColumns(#"Renamed Columns",{{"Attribute",each "QA" & _, type text}}),
combined = #"Unpivoted Only Selected Columns" & #"Change Title",
#"Changed Type" = Table.TransformColumnTypes(combined,{{"Attribute", type text}, {"Value", type text}}) ,
#"Pivoted Column" = Table.Pivot(#"Changed Type", List.Distinct(#"Changed Type"[Attribute]), "Attribute", "Value")
in #"Pivoted Column"
or with changed function as below,
let srcTbl = Table.FromRows(
{
{1, "Bob", "Smith", "123-4567"},
{2, "Jim", "Brown", "987-6543"},
{3, "Paul", "Wick", "543-7890"}
},
{"CustomerID", "FirstName", "LastName", "Phone"}
),
List = {"CustomerID", "FirstName", "LastName"},
#"Unpivoted Only Selected Columns" = Table.Unpivot(srcTbl, List, "Attribute", "Value"),
#"Changed Type1" = Table.TransformColumnTypes(#"Unpivoted Only Selected Columns",{{"Value", type text}}),
#"Processed" = Table.TransformColumns(#"Changed Type1",{{"Value",each fnCheckId2(_), type text}}),
Namechange = Table.TransformColumns(Processed,{{"Attribute",each "QA "&_, type text}}),
combined = #"Changed Type1" & Namechange,
#"Pivoted Column" = Table.Pivot(combined, List.Distinct(combined[Attribute]), "Attribute", "Value")
in #"Pivoted Column"
with fnCheckId2
( clm as text)=>
let
z = if Text.Length(clm )>3 then "Ok" else "Nok"
in z

Answer 2

Please try this loop example:
loops ParametersList list
Use fnCheckId function output table as input for next loop
Do NOT require knowledge about looping function fnCheckId
Recursive function Loop_fnCheckId:
(Loop as number, inTbl as table, inPrm as list )=>
try Loop_fnCheckId(Loop-1, fnCheckId(inTbl, inPrm{Loop-1}),inPrm)
otherwise inTbl
code with loop:
let
ParametersList = {"CustomerID","FirstName","LastName"},
cntLoop = List.Count(ParametersList),
Result = Loop_fnCheckId(cntLoop,srcTbl, ParametersList)
in Result
P.S. The question: is it possible to rewrite it using each _ syntax and avoid additional looping function Loop_fnCheckId