Ensure run Method Returns Dictionary with Annotated Values

[vblagoje]

Description:

Haystack component developers sometimes forget to adhere to the expected return type of the run method in various components. Specifically, the run method is designed to return a dictionary with values that are annotated on the method.

Issue Details:

• Expected Behavior: The run method, across different components, should return a dictionary where the keys are the annotated output types, and the values are the corresponding results.
• Current Behavior: Users sometimes return only the values without encapsulating them in a dictionary, as the output annotations specify.
• Impact: This inconsistency can lead to pipeline runtime errors; users find out at Pipeline run time that they made a mistake. We should warn them earlier - at code time.

Example:

A correct implementation of the run method looks like this:

@component.output_types(documents=List[Document])
def run(self, ...):
    ...
    return {"documents": docs}

However, users often incorrectly implement it as:

@component.output_types(documents=List[Document])
def run(self, ...):
    ...
    return docs

[tanaymeh]

Hi @vblagoje, I would like to take up this issue as my first OS contribution at Haystack, if I am allowed to!

Thanks!

[sahusiddharth]

@vblagoje I went through all the files, all of them are returning dictionaries but the keys have a multitude of key names from answers to replies to values to document_written.

Do you want documents as a key in all return dictionaries?