fix: make PromptBuilder input parameters mandatory

[LastRemote]

Related Issues

• fixes All input parameters in PromptBuilder are optional #7441

Proposed Changes:

Make {'is_mandatory': True} for all PromptBuilder inputs. PromptBuilder will now check the input variables during pipeline runs and throw ValueError if some of the template variables found in jinja templates are missing.

How did you test it?

Tested by following the 2.0 RAG pipeline recipe from https://docs.haystack.deepset.ai/docs/creating-pipelines

Notes for the reviewer

Not sure if this needs a new unit test for a small change like this, but I can definitely go add one if necessary.
An additional question would be if PromptBuilder.run() should check these parameters as well. I decided to leave it alone since this willwould alter the behavior in test.components.builders.test_run_without_input(), but it makes sense either way.

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test:.
• I documented my code
• I ran pre-commit hooks and fixed any issue

[CLAassistant]

All committers have signed the CLA.

[coveralls]

Pull Request Test Coverage Report for Build 8490134263

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 89.532%

---

Totals
Change from base Build 8466615213:	0.0%
Covered Lines:	5568
Relevant Lines:	6219

---

💛 - Coveralls

[shadeMe]

Thanks for the PR! Would you mind adding a release note as well?

[LastRemote]

Thanks for the PR! Would you mind adding a release note as well?

Thanks for the reply. Sure, I can add a release note to this, but I believe the issue still needs further discussion and we might need to change the implementation accordingly to avoid potential breaking changes (see #7441).

[LastRemote]

Closing this PR in favor of #7553