🧩 daplug-core (da•plug)

Shared schema + event plumbing for daplug- adapters*

daplug-core is the tiny layer of glue that both daplug-ddb, daplug-cypher, and future daplug-* projects, relied on in their old common/ directories. It bundles a publisher, logging shim, schema utilities, and merge helpers so the higher-level adapters can stay laser-focused on their respective datastores. This repository is not meant to be a fully fledged adapter on its own—it simply centralizes the primitives the adapters share.

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🌈 Why this exists

• Single source of truth – The DynamoDB and Cypher adapters used to carry duplicate copies of the same helpers. daplug-core keeps those modules in one place.
• Batteries-included SNS publishing – The base publisher encapsulates SNS fan-out, FIFO metadata, and logging so consuming packages can just hand it messages.
• Schema-first tooling – schema_loader and schema_mapper read OpenAPI/JSON schemas and project payloads to the shapes your adapters expect.
• Deterministic merging – dict_merger upgrades nested payloads with configurable list/dict strategies (add, replace, remove) so you can keep optimistic writes tight.

If you are migrating daplug-ddb or daplug-cypher, remove their legacy common/ folder and import from daplug_core instead. Nothing else changes.

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📦 Installation

pip install daplug-core
# or
pipenv install daplug-core

Not on PyPI yet? Until release, install straight from the repo:

pip install git+https://github.com/paulcruse3/daplug-core.git

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🔁 How consuming packages use the base

1. Declare the dependency in the adapter package (e.g. daplug-ddb) via Pipfile/pyproject.
2. Drop the duplicated modules (common/logger.py, common/publisher.py, etc.).
3. Import from daplug_core wherever those utilities were previously referenced.

# inside daplug-ddb
from daplug_core import dict_merger, json_helper, publisher, schema_mapper

merged = dict_merger.merge(original, incoming, update_list_operation="replace")
publisher.publish(arn=sns_arn, data=merged, attributes={"event": "updated"})

Because the API surface stayed the same, adapter code typically only needs import-path updates.

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🧱 Building blocks

Module	Purpose
base_adapter.BaseAdapter	Minimal SNS-aware adapter scaffold (used as a mixin by higher-level adapters).
publisher.publish	Thin wrapper over boto3 SNS clients with FIFO group/dedupe support and structured logging.
logger.log	Consistent JSON stdout logging that honors RUN_MODE=unittest.
json_helper	Best-effort try_encode_json / try_decode_json helpers used by loggers and publishers.
schema_loader.load_schema	Loads an OpenAPI/JSON schema and resolves $refs using jsonref.
schema_mapper.map_to_schema	Recursively projects payloads into schema-shaped dictionaries (supports allOf inheritance).
dict_merger.merge	Deep merge with per-call list/dict strategies (add, remove, replace, upsert).

Mix and match these pieces inside datastore-specific adapters.

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🧭 Example: refactoring daplug-ddb

# before (inside daplug_ddb/common/publisher.py)
from . import logger
import boto3

# after
from daplug_core import publisher

publisher.publish(
    arn=self.sns_arn,
    data=payload,
    fifo_group_id=fifo_group,
    fifo_duplication_id=fifo_dedupe,
    attributes={"source": "daplug-ddb"},
)

# before
from .common.dict_merger import merge

# after
from daplug_core import dict_merger

updated_item = dict_merger.merge(original, patch, update_list_operation="replace")

The same pattern applies inside daplug-cypher when merging node payloads or formatting SNS events.

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⚙️ Local development

git clone https://github.com/paulcruse3/daplug-core.git
cd daplug-core
pipenv install --dev

Run tests & coverage

pipenv run test       # pytest tests/
pipenv run test-cov   # pytest --cov=daplug_core --cov-report=term-missing
pipenv run lint       # pylint --fail-under 10 daplug_core

Ship updates downstream

1. Bump the version in setup.py (and setup.cfg if needed).
2. Publish to PyPI or deliver a git tag.
3. Update daplug-ddb and daplug-cypher to depend on the new version.
4. Remove any residual common/ references in those repos and re-run their suites.

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🤝 Contributing

Pull requests are welcome—especially improvements that make life easier for the DynamoDB and Cypher adapters. If you add a helper here, remember to wire it up in the consuming packages as well.

git checkout -b feat/better-schema-mapper
pipenv run test-cov
pipenv run lint
git commit -am "feat: better schema mapper"

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📄 License

Apache 2.0 – see LICENSE.