Forum Discussion
Is it possible to create a query from text?
I have a scenario where I need to generate a dynamic query and wondered if it is possible to do so by "creating" a query from text.
For example, if I had a text field that contained the following:
let
Source = 1 = 1
in
Sourcecould that then be executed as a query somehow?
Yes. You can use Expression.Evaluate("M expression") for that.
Expression.Evaluate - PowerQuery M | Microsoft Docs
Pat
4 Replies
Yes. You can use Expression.Evaluate("M expression") for that.
Expression.Evaluate - PowerQuery M | Microsoft Docs
Pat
Very cool! Didn't know about that function, mahoneypat. Can this handle more complex queries? I keep getting an error when I try something like the following:
= Expression.Evaluate( "Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText(""i45WclTSUTI0MFCK1YlWcgKyjaBsZyDbGMSOBQA="", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Name = _t, Value = _t]), #""Changed Type"" = Table.TransformColumnTypes(Source,{{""Name"", type text}, {""Value"", Int64.Type}}), #""Filtered Rows"" = Table.SelectRows(#""Changed Type"", each ([Name] = ""B""))""""")Here's the original in the Advanced Editor:
and here's the original code:
let Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WclTSUTI0MFCK1YlWcgKyjaBsZyDbGMSOBQA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Name = _t, Value = _t]), #"Changed Type" = Table.TransformColumnTypes(Source,{{"Name", type text}, {"Value", Int64.Type}}), #"Filtered Rows" = Table.SelectRows(#"Changed Type", each ([Name] = "B")) in #"Filtered Rows"
Looks like you are missing the let and in parts of your query inside your Expression.Evaluate.
Pat
That did the trick! It's a bummer the applied steps aren't listed using this method, but the method is great just the same. Appreciate it!
