PydantiCRUD

Supercharge your Pydantic models with CRUD methods and a pluggable backend

pydanticrud let's you add a few details to your pydantic models to get basic CRUD methods automatically built into your models for the backend of your choice.

Usage

from pydanticrud import BaseModel, DynamoDbBackend

class User(BaseModel):
    id: int
    name: str

    class db_config:
        table_name = 'User'
        backend = DynamoDbBackend
        hash_key = 'id'

First, use the BaseModel from pydanticrud instead of pydantic.

Next add your backend to your model's db_config class. PydantiCRUD is geared toward DynamoDB but provides SQLite for lighter-weight usage. You can provide your own if you like.

Finally, add appropriate members to the db_config class for the chosen backend.

Methods

Model Methods

get(id) - return and instance of the Model from the backend indexed by id.

exists() - detect if the model (table) exists in the backend

initialize() - setup the model (table) in the backend

delete(id) - delete the record from backend

query(rule) - return a list of records that satify the rule. Rules are defined by rule-engine for querying or filtering the backend.

NOTE: Rule complexity is limited by the querying capabilities of the backend.

Instance Methods

save() - store the Model instance to the backend

batch_save() - store the List of Model instance to the backend

DynamoDB

get(key: Union[Dict, Any])

• key can be any of 3 types:
  • in the case of a single hash_key, a value of type that matches the hash_key
  • in the case of a hash and range key, a tuple specifying the respective values
  • a dictionary of the hash and range keys with their names and values. This method can pull for alternate indexes.

query(query_expr: Optional[Rule], filter_expr: Optional[Rule], limit: Optional[str], exclusive_start_key: Optional[tuple[Any]], order: str = 'asc'

• Providing a query_expr parameter will try to apply the keys of the expression to an existing index.
• Providing a filter_expr parameter will filter the results of a passed query_expr or run a dynamodb scan if no query_expr is passed.
• An empty call to query() will return the scan results (and be resource intensive).
• Providing a limit parameter will limit the number of results. If more results remain, the returned dataset will have an last_evaluated_key property that can be passed to exclusive_start_key to continue with the next page.
• Providing order='desc' will return the result set in descending order. This is not available for query calls that "scan" dynamodb.

count(query_expr: Optional[Rule], exclusive_start_key: Optional[tuple[Any]], order: str = 'asc'

• Same as query but returns an integer count as total. (When calling query with a limit, the count dynamodb returns is <= the limit you provide)

Backend Configuration Members

hash_key - the name of the key field for the backend table

DynamoDB

hash_key - the name of the partition key field for the backend table.

range_key - (optional) the name of the sort key field for the backend table for composite key tables.

region - (optional) specify the region to access dynamodb in.

endpoint - (optional) specify an endpoint to use a local or non-AWS implementation of DynamoDB

local_indexes - (optional) specify a mapping of index-name to tuple(partition_key).

global_indexes - (optional) specify a mapping of index-name to tuple(partition_key).

ttl - (optional) the name of the datetime-typed field that dynamo should consider to be the TTL field. PydantiCRUD will save this field as a float type instead of an ISO datetime string. This field only works properly with UTC-zoned datetime instances.

SQLite (Python 3.7+)

database - the filename of the database file for SQLite to use

Roadmap

There is plenty of room for improvement to PydantiCRUD.

• Backend feature support not being consistent is the most egregious flaw that can be incrementally improved.

• SQLite JSON1 extension support for more powerful queries.

• Add more backends

  • REST API
  • Redis
  • Postgres/MySQL

Tools

Testing

You can run unittests with poetry run pytest

Formatting

You can format the code by running:

for d in pydanticrud tests; do poetry run black $d; done