Power Query Configurable / Dynamic If Statement

Thanks artemus ,

that circumvents the combination of the forumula dependencies with the row context nicely.

Is this a general limitation when using Expression.Evaluate or do you think that the error is due to some specific settings within this sample?

hnguyen76 ,

I've rewritten it slightly to make it easier to swap the sample code against your actual data.
Also, I've included a "List.Select"-statement to grab the correct value from evaluated conditions:

 

 

let
    ConditionsFromExcelTable = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WykxT0lGKDkvNS8kvilWwVYhRCk7MLchJNYxRAkqUZKTmASmIkFKsDky9f1Fmun9BalFiSX6RZwpEX1JReoySQmJeikJ0cGVxSWouRNgxANmkoNTi0pwSQySj0NUq5BehGhDgj2yAY0CAP0J3SGpFiZ5zfl5JYmZesQbMGzoKcG8YxShpYvojFgA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Hypothesis = _t, Condition = _t, Conclusion = _t, Result = _t]),
    
    AddFunctionColumToConditions = let
        Source = ConditionsFromExcelTable,
        #"Changed Type" = Table.TransformColumnTypes(Source,{{"Hypothesis", type text}, {"Condition", type text}, {"Conclusion", type text}, {"Result", type text}}),
        GenerateFunctions = Table.AddColumn(#"Changed Type", "Function", each Expression.Evaluate("each if " & [Condition] & " then """ & [Result] & """ else null", [Text.Contains = Text.Contains, Comparer.OrdinalIgnoreCase = Comparer.OrdinalIgnoreCase]))
    in
        GenerateFunctions,

    SourceData = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMlTSUQpOzC3ISTUCsYyBhG9inlKsTrSSEVwKpCg9H0i4FwWBpYzhUiBWUlE6kHQMAEuZwKVArKTUVKhULAA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [ID = _t, Vendor = _t, OrigOperatorId = _t, System = _t]),
    #"Changed Type" = Table.TransformColumnTypes(SourceData,{{"Vendor", type text}, {"OrigOperatorId", type text}, {"System", type text}}),

    Evaluate = Table.AddColumn(
        #"Changed Type", 
        "Custom", 
        each List.First(List.Select(List.Transform(AddFunctionColumToConditions[Function], (fn) => fn(_)), each _ <> null))
        )
in
    Evaluate