Power Query M - Change proper case for first row of the table

[parry2k]

how can I can transform (proper case) of all column in first rows of the table in Power Query 

[MarcelBeug · Accepted solution]

Example for the first 2 rows:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45W8nD18fFX0lEK9w/ycVGK1YlWSi1LLaosycjMSwcKp2XmpdqDhfNSy4H8ovxyMC8xL78kI7UIJhILAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [Column1 = _t, Column2 = _t]),
    Typed = Table.TransformColumnTypes(Source,{{"Column1", type text}, {"Column2", type text}}),
    ProperCaseFirst2Rows = Table.TransformColumns(Table.FirstN(Typed,2),{}, Text.Proper) & Table.Skip(Typed,2)
in
    ProperCaseFirst2Rows

[Anonymous]

@MarcelBeug

Are  you using {} empty list (highligted in red) to account for the second argument in Table.TransformColumns () ? Or there is another logic here ?  Is this by the way an empty list or a full list since function applies to all the values ? 

Table.TransformColumns(
        Table.FirstN(Typed,2),
         {},   
         Text.Proper
)

Thanks

[MarcelBeug]

The {} is an empty list.

In this case it means that no transform operations are supplied as the second argument.

Instead, the 3rd argument is supplied, being the default Transformation function. i.e. the default operation that applies to the columns for which no specific transform operations are specified in the second argument.

[Anonymous]

@MarcelBeug

Thanks for the answer. 

I have a question on  transformOperations  what arguemnts does it take in its list? 

In the example, provided in the formula reference Table.TransformColumns second argument (The list of transformOperations to run) converts text column to number.  

So, when we see transformOperations should we assume that it takes   {column to change, function} ? ( or as it shown in the example {"A", Number.FromText} )

Table.TransformColumns(      
   Table.FromRecords({[A="1", B=2], [A="5", B=10]}),      
   {"A", Number.FromText}
)   
equals  Table.FromRecords({[A=1,B=2], [A=5,B=10]}) 

Argument Description

table	The Table to modify.
transformOperations	The list of transformOperations to run.
optional defaultTransformation	The default table transformation.
optional missingField	Missing field value.

[MarcelBeug]

Almost.

There is another, optional, third argument, in which you can specify the resulting column data type.

This information is not available in any docuentation I could find, but if you use standard menu options on the Transform tab, then the generated code includes that third argument, e.g. after chosing menu option Date - Month - End Of Month:

= Table.TransformColumns(Typed,{{"Date", Date.EndOfMonth, type date}})

I'm not sure if that third argument is always present in generated code via the Transform tab.

[Anonymous]

@MarcelBeug

Thank you very much. 

Just one last note. Are we wrapping the list of transformOperations as a list or list of lists (one set of curly brackets or two)?  

= Table.TransformColumns(Typed,{{"Date", Date.EndOfMonth, type date}})

Thanks again.

[MarcelBeug]

It is a list of lists, 2 curly brackets: you can specify transformations for multiple columns, and each specification has 2 or 3 items.

{{"Column1", operation1},{"Column2", operation2}, etcetra}

[parry2k]

Thanks that did it. Cheers!