[Feature] --empty flag should be exposed in flags variable

[jlucas91]

Is this a new bug in dbt-core?

• I believe this is a new bug in dbt-core
• I have searched the existing issues, and I could not find an existing issue for this bug

Current Behavior

When running dbt 1.8 EMPTY is not present on the flags variable.

Expected Behavior

When using the --empty flag, I would expect EMPTY to be set to true. This is would bring it in line with other first class flags like full-refresh and fail-fast.

Steps To Reproduce

1. ./dbt run --empty
2. Within a model, include {{ print(flags) }}
3. FLAGS is not present

Relevant log output

No response

Environment

- OS:
- Python:
- dbt:

Which database adapter are you using with dbt?

snowflake

Additional Context

It does not appear to be included in the flags module https://github.com/dbt-labs/dbt-core/blob/HEAD/core/dbt/flags.py

[dbeatty10]

Thanks for reaching out @jlucas91 !

This sounds more like a feature request to me. Can you share more why this seems like a bug to you?

[jlucas91]

I think it could go either way and no worries on my end if you'd prefer to reclassify.

It felt like a potential unintentional miss in the --empty flag release to me, which is why I leaned towards calling it a bug. While the documentation does state the code is the source of truth for what flags are included in the variable, it seemed strange for a significant and first class flag to be omitted from the interface.

[jtcohen6]

For what it's worth, I do buy this as a thing we should do!

Among other things, this might enable us to provide users with slightly more flexibility & customization while working around known edge cases of --empty.

As an example:

• [Bug] --empty flag not working on Pseudo-columns dbt-bigquery#1243 (comment)

[jlucas91]

That's exactly how I bumped into the flags limitation @jtcohen6 ! I'm doing a lot of checks like this right now to guard the various limitation cases we've bumped into:

{% set empty_run = '--empty' in flags.INVOCATION_COMMAND %}
{% if empty_run %}
-- compatibility code
{% else %}
-- model code
{% endif %}

That's pretty gross and will get nicer with the flags change. To take it one step further we've opted to implement a is_empty_run macro to clean up the syntax even more. A similar macro might be nice to roll into core DBT as a bit of syntactic sugar for users (similar to is_incremntal()).