Error wile bulk changing column names in Power Query

[mmp]

I'm trying to bulk change column names with power query and i'm stuck with an error i can't understand : 

For that i've followed a very interesting post of Soheil Bakhshi : https://www.biinsight.com/a-power-query-custom-function-to-rename-all-columns-at-once-in-a-table/#mo...

for the function :

//fnRenameColumnsFromRefQuery
(ColumnName as text) as text =>
let
    Source = 
        if (
            List.Contains(
                Record.FieldNames(#sections[Section1]), 
                "Column Names Mapping"
                ) 
             ) = true 
        then #"Column Names Mapping" 
        else null,
    ColumnNewName = 
        try 
            if List.Contains(Source[Column Name], ColumnName) = true 
            then 
                if Text.Trim(Table.SelectRows(Source, each ([Column Name] = ColumnName)){0}[Description]) = "" 
                then ColumnName 
                else Table.SelectRows(Source, each ([Column Name] = ColumnName)){0}[Description] 
            else Source 
        otherwise ColumnName
in
    ColumnNewName

Then the code used for changing in my data source table :

let
    Source = Sql.Database("XXX.XXX.XXX.XXX", "XXXXXXX"),
    dbo_HCR120P = Source{[Schema="dbo",Item="HCR120P"]}[Data],
    #"Type modifié" = Table.TransformColumnTypes(dbo_HCR120P,{{"PACSOC", type text}, {"PACPAY", type text}, {"PALPAY", type text}, {"PAFCEE", type text}, {"PACINS", type text}, {"PACLGU", type text}, {"PACSEC", type text}, {"PANCTT", type text}, {"PAADAC", type text}, {"PAMDAC", type text}, {"PAJDAC", type text}}),
    #"Rename Column" = Table.TransformColumnNames(#"Type modifié", fnRenameColumnsFromRefQuery)
in
    #"Rename Column"

Could you guys help me and tell me what's wrong ?

Kind regards,

Mohammad

[Jimmy801 · Accepted solution]

Hello @mmp 

the problem is in your else clause. Use this code instead

//fnRenameColumnsFromRefQuery
(ColumnName as text) as text =>
let
    Source = 
        if (
            List.Contains(
                Record.FieldNames(#sections[Section1]), 
                "Column Names Mapping"
                ) 
             ) = true 
        then #"Column Names Mapping" 
        else null,
    ColumnNewName = 
        try 
            if List.Contains(Source[Column Name], ColumnName) = true 
            then 
                if Text.Trim(Table.SelectRows(Source, each ([Column Name] = ColumnName)){0}[Description]) = "" 
                then ColumnName 
                else Table.SelectRows(Source, each ([Column Name] = ColumnName)){0}[Description] 
            else ColumnName
        otherwise ColumnName
in
    ColumnNewName

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Have fun

Jimmy