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Anonymous's avatar
Anonymous
Not applicable
3 years ago
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How to reference list of lists in Table.RenameColumns function?

Table.RenameColumns takes two values -- the table you want to modify, and a list (or list of lists) containing the old and new column names.  Example given in Power Query documentation: Replace the...
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  • ImkeF's avatar
    ImkeF
    3 years ago

    Hi Anonymous ,
    just omit the merge step and you should be good to go:

    let
Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WilHyz0nxS8xNNYxRUtIBcv1Sy2HcWB0keSNUeSN0eWNUeRA3NhYA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [OldNames = _t, NewNames = _t]),
#"Changed Type" = Table.TransformColumnTypes(Source,{{"OldNames", type text}, {"NewNames", type text}}),
#"create list of lists" = Table.ToRows(#"Changed Type")
in
#"create list of lists"


    By merging the columns, you are creating one string that will then become a list with just one element.
    But you need a list with 2 elements in it. So omitting the merge will just solve the issue.

ImkeF's avatar
ImkeF
Community Champion
3 years ago

Hi Anonymous ,
just omit the merge step and you should be good to go:

let
Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WilHyz0nxS8xNNYxRUtIBcv1Sy2HcWB0keSNUeSN0eWNUeRA3NhYA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [OldNames = _t, NewNames = _t]),
#"Changed Type" = Table.TransformColumnTypes(Source,{{"OldNames", type text}, {"NewNames", type text}}),
#"create list of lists" = Table.ToRows(#"Changed Type")
in
#"create list of lists"


By merging the columns, you are creating one string that will then become a list with just one element.
But you need a list with 2 elements in it. So omitting the merge will just solve the issue.

Anonymous's avatar
Anonymous
Not applicable
2 years ago

Hi Imke -- 

 

The example I provided you worked after I made that adjustment in my query. But when I ran the same steps on my actual data, I am still getting the same error, even though I have a nested list: 

Expression.Error: We expected a RenameOperations value.
Details:
[List]

 

For some reason, my query doesn't seem to recognize that the query with my nested list is a list.