Engine: Do not evaluate predicates where there are zero rows

[SeanAdams]

In cases where there are dynamic tools - you often get a situation where there are zero rows returned - which means that the output of something like a transpose or a JSON parse or a regex may not have the field names expected.

However - any downstream filter tools (or other similar tools) fail even though there are no rows (see screenshot below).

The only way to get around this is to insert fake rows using a union or use the CReW macro for Ensure Fields.    However, this is all waste since there are no rows so there's no point in even evaluating the predicate in the filter tool.     Rather than making users work around this - can we please change the engine so that a tool can avoid evaluation if there are zero rows - this will significantly reduce the amount of these kind of workaround that need to be used with any dynamic tools (including any API calls).

thank you

Sean

[jarrod]

The other solution i can see to this problem is having the ability to save a schema in a tool. @SeanAdams, Imagine being able to save an example API response to later be parsed when in dev mode... that saves on API calls and allows for faster iteration since you aren't hitting an external API just to get sample data downstream.  

[patrick_digan]

This is annoying to try and build around when it pops up.

[TonyaS]

Thanks @SeanAdams 

I wanted you to know that this has been added to our internal Intake for product ideas.