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Replace multiple nulls at once in Power Query

I've got a table with a few columns of numerical data, and a few with text data. For all of the numerical columns, where the value is null, I want to replace those with a 0. For columns where it is text, I'd like to replace it with something along the lines of "Undefined" or the like. 


Looking at functions like Table.TransformColumns and Table.ColumnsOfType, I feel like I should be able to add a step that goes in and replaces all the nulls at once, rather than having to click and replace each value one at a time. Is this possible?


Are there any good resources for picking up more complex M? I'm having a hard time figuring out when I just missed a casing or letter, or when I've completely missed how the entire concept works. 


Hi @Anonymous


This worked for me


= Table.ReplaceValue(#"Renamed Columns",null,0,Replacer.ReplaceValue,{"Col 1", "Col 2", "Col 3", "Col 4"})

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The same way as @Phil_Seamark but using the UI. Press "Ctrl" to select multiple columns and replace the values.





A more dynamic approach below. I splitted the solution in separate steps just for clarity.

Input is in Table1


Query TableShema:




Query NumberColumns returns a list of number columns in Table1: 


    Source = TableSchema,
    #"Filtered Rows" = Table.SelectRows(Source, each ([Kind] = "number")),
    Name = #"Filtered Rows"[Name]


Query TextColumns returns a list of text columns in Table1:


    Source = TableSchema,
    #"Filtered Rows" = Table.SelectRows(Source, each ([Kind] = "text")),
    Name = #"Filtered Rows"[Name]


Query Result replaces the values in Table1:


    Source = Table1,
    #"Replaced Value" = Table.ReplaceValue(Source,null,0,Replacer.ReplaceValue,NumberColumns),
    #"Replaced Value1" = Table.ReplaceValue(#"Replaced Value",null,"Undefined",Replacer.ReplaceValue,TextColumns)
    #"Replaced Value1"


Specializing in Power Query Formula Language (M)
Not applicable

@MarcelBeug, this is much closer to what I had envisioned with some of the capabilities. I came across something similar to what I was thinking, but this was only to change a column header. It's just a step you add anywhere in your power query to transform the headers to a clean name, regardless of what's there. I think something like this is possible with the data types, but it might be a lot longer given the work needed for figuring out the Kind.



#"Alter Column Names" = Table.TransformColumnNames( #"<<<Previous Change Name>>>", ( columnName as text ) as text => Text.Combine( List.Transform( Text.Split( columnName, "_" ), each if Text.Length( _ ) >= 4 then Text.Proper( _ ) else _ ), " ") ),

Thanks for the thumbs up, but I'm really confused by your previous post.

Your question was about replacing null values, so what have column headers to do with that??

Is your initial question answered?

Is your previous post just a remark or a new question?

In the latter case you'd better mark this topic as answered and raise a new topic.

Specializing in Power Query Formula Language (M)
Frequent Visitor

Motivation from solution above ... as I needed to replace null values in the whole table without specifying columns - modified a bit suggested formula:
= Table.ReplaceValue(Source,null,0,Replacer.ReplaceValue,Table.ColumnNames(Source))


where Source - a reference to the data table.

many thanks for this. It helped me solve the exact same issue I was having.

Super User III
Super User III

I believe you already looked at this link



You can use replace function query editor and it will add step for you.

Did I answer your question? Mark my post as a solution.

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