Structured Error Message String Interpolation - Non-Text -> Text Conversions

[Ben-Dev]

Hello,

When an error's Message.Parameters are interpolated into its Mesasge.Format to generate its Message, non-text parameters are automatically rendered as text. I'm wondering about a couple details of this conversion:

• Behind the scense, is Text.From used to conver scalar values to text?
• It looks like complex values (like table or list) are represented in the interpolated text simply by their literlal type name (e.g. any table will be interpolated into the Message simply as the literal word "table"). Is that always the behavior, or are there cases I'm missing?

Thank you!

[artemus · Accepted solution]

The parameters of an error message function the same as Text.Format, which will format complex types like record, table and list, in addition to type as their simple type name. For most cases in depth details about an error belong in the Details field.

[jennratten]

Hello - error messages and the data type system are very complex topics.  Here are some resources that can help.

https://bengribaudo.com/blog/2020/01/15/4883/power-query-m-primer-part-15-error-handling 

https://radacad.com/exception-reporting-in-power-bi-catch-the-error-rows-in-power-query 

https://docs.microsoft.com/en-us/powerquery-m/power-query-m-type-system 

https://docs.microsoft.com/en-us/powerquery-m/m-spec-error-handling 

https://docs.microsoft.com/en-us/powerquery-m/m-spec-consolidated-grammar 

https://docs.microsoft.com/en-us/powerquery-m/m-spec-lexical-structure 

[Ben-Dev]

Thank you, @artemus and @jennratten!