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k1s2's avatar
k1s2
Helper I
2 years ago
Solved

Error converting data type to date but not if converting data type to datetime first

I have data in a column detected as text like this 18/05/2021 15:15:33    If I try to transform it to date, PowerBI throws an error 'couldn't parse the input as a Date value'   If I try to transf...
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  • AlienSx's avatar
    AlienSx
    2 years ago
    let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMrTQNzDVNzIwMlQwNLUCImNjpdhYAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [data = _t]),
    to_date = Table.TransformColumns(Source, {"data", each Date.From(DateTime.From(_, "de-DE"))})
in
    to_date
k1s2's avatar
k1s2
Helper I
2 years ago

Thanks,

So the line for converting multiple columns to UK date format in one step would be something like:

 

= Table.TransformcolumnTypes(Source,{{"This Date", each Date.From(DateTime.From(_, "en-GB"))},{"That Date", each Date.From(DateTime.From(_, "en-GB"))}})

 

AlienSx's avatar
AlienSx
Super User
2 years ago

No. Don't use Table.TransformColumnTypes. Use this 

    = Table.TransformColumns(
        Source,
        {{"This Date", each Date.From(DateTime.From(_, "en-GB")), type date},
        {"That Date", each Date.From(DateTime.From(_, "en-GB")), type date}}
    )
  • k1s2's avatar
    k1s2
    Helper I
    2 years ago

    Thanks,

     

    I'm having trouble applying it to all columns ending with the word 'Date".

     

    I tried:

    = Table.TransformColumns(
  #"prevstep",
   {List.Transform(List.Select(Table.ColumnNames#"prevstep"), eachText.EndsWith(_,"Date"))),
   each Date.From(DateTime.From(_, "en-GB")), type date}
 )

     

    ...but got an "expression error 1 arguments were passed to a function which expects 2",

     

    Where am I going wrong

    • AlienSx's avatar
      AlienSx
      Super User
      2 years ago

       

       

       

      Table.ColumnNames#"prevstep")

       

       

      no opening bracket. You are trying to wrap everything into one single step. Don't be afraid to write your calcs down step by step - more chances to catch a real reason of your error when you are new to M. This does not always slow down your code.

      • k1s2's avatar
        k1s2
        Helper I
        2 years ago

        If I understand your suggestion, your point is taken that making it work it 2 steps is fine, but I suppose 1 step is more efficient.

         

        Two simple steps for one column are straightforward for me like this:

         

            #"Changed Type" = Table.TransformColumnTypes(prevstep,{{"Date & Time", type datetime}}),
    #"Changed Type1" = Table.TransformColumnTypes(#"Changed Type",{{"Date & Time", type date}}),

         

        Also,

        Table.TransformColumnTypes(prevstep,List.Transform(List.Select(Table.ColumnNames#"prevstep"), eachText.EndsWith(_,"Date"))),

        Seems to work, but combing them I still can't get it working.  This:

         

         

        = Table.TransformColumns(#"prevstep",
   {List.Transform(List.Select(Table.ColumnNames,(#"prevstep"), 
    each Text.EndsWith(_,"Date"))),
   each Date.From(DateTime.From(_, "en-GB")), type date})

         

        now gives me 

        Expression.Error: 3 arguments were passed to a function which expects 2.
        Details:
        Pattern=
        Arguments=[List]