feat: Add JSONConverter Component

[silvanocerza]

Related Issues

• fixes JSON Convertor : Pipeline Component #7784

Proposed Changes:

Add a new JSONConverter Component.

Usage:

import json

from haystack.components.converters import JSONConverter
from haystack.dataclasses import ByteStream

data = {
    "laureates": [
        {
            "firstname": "Enrico",
            "surname": "Fermi",
            "motivation": "for his demonstrations of the existence of new radioactive elements produced "
            "by neutron irradiation, and for his related discovery of nuclear reactions brought about by"
            " slow neutrons",
        },
        {
            "firstname": "Rita",
            "surname": "Levi-Montalcini",
            "motivation": "for their discoveries of growth factors",
        },
    ],
}
source = ByteStream.from_string(json.dumps(data))
converter = JSONConverter(
    jq_schema=".laureates[]", content_key="motivation", extra_meta_fields=["firstname", "surname"]
)

results = converter.run(sources=[source])
documents = results["documents"]
print(documents[0].content)
# 'for his demonstrations of the existence of new radioactive elements produced by
# neutron irradiation, and for his related discovery of nuclear reactions brought
# about by slow neutrons'

print(documents[0].meta)
# {'firstname': 'Enrico', 'surname': 'Fermi'}

print(documents[1].content)
# 'for their discoveries of growth factors'

print(documents[1].meta)
# {'firstname': 'Rita', 'surname': 'Levi-Montalcini'}

How did you test it?

I added unit tests.

Notes for the reviewer

N/A

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

[coveralls]

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Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.06%) to 90.297%

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Totals
Change from base Build 11011481624:	-0.06%
Covered Lines:	7408
Relevant Lines:	8204

---

💛 - Coveralls

[shadeMe]

Suggested change

	extra_meta_fields: Optional[List[str]] = None,
	extra_meta_fields: Optional[Set[str]] = None,

[shadeMe]

Let's wrap this in exception handling and handle decoding errors - malformed inputs are a common enough occurrence that it makes sense to rethrow/warn with an expanded error message (w/t the file path).

[silvanocerza]

@sjrl the strings in here are meant to be paths like other converters. If there needs be in the future we can treat them as JSON strings too.

[sjrl]

Good to know! I don't think there is any need for us to work directly with JSON strings right now. File paths is fine.

[dfokina]

Pls add this to pydocs too 🙏

[sjrl]

Looks great @silvanocerza! My main wish was that this component could also serve as basically a Document.from_dict call and it looks like it can handle that. To give context, we have cases where we create Haystack Documents locally and then want to load them directly in dC as JSON files.

I think the only request/question I have is it possible to set one content key and then say all other fields should automatically be treated as metadata fields? We often have the case that data is messy (go figure) and not all files we are ingesting have the same metadata keys (but the same content key) and we'd want to make sure we grab all of them and needing to manually specify could be cumbersome.

[dfokina]

Going to push some docstring updates real quick 👀