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engine.py
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engine.py
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import asyncio
from asyncio.tasks import gather
from typing import (
Any,
AsyncGenerator,
AsyncIterable,
Awaitable,
Dict,
Generator,
Generic,
List,
Optional,
Sequence,
Tuple,
Type,
TypeVar,
Union,
cast,
)
from motor.motor_asyncio import (
AsyncIOMotorClient,
AsyncIOMotorClientSession,
AsyncIOMotorCollection,
AsyncIOMotorCursor,
)
from pydantic.utils import lenient_issubclass
from odmantic.exceptions import DocumentNotFoundError
from odmantic.field import FieldProxy, ODMReference
from odmantic.model import Model
from odmantic.query import QueryExpression, SortExpression, and_
ModelType = TypeVar("ModelType", bound=Model)
SortExpressionType = Optional[Union[FieldProxy, Tuple[FieldProxy]]]
class AIOCursor(
Generic[ModelType], AsyncIterable[ModelType], Awaitable[List[ModelType]]
):
"""This object has to be built from the [odmantic.engine.AIOEngine.find][] method.
An AIOCursor object support multiple async operations:
- **async for**: asynchronously iterate over the query results
- **await** : when awaited it will return a list of the fetched models
"""
def __init__(self, model: Type[ModelType], motor_cursor: AsyncIOMotorCursor):
self._model = model
self._motor_cursor = motor_cursor
self._results: Optional[List[ModelType]] = None
def _parse_document(self, raw_doc: Dict) -> ModelType:
instance = self._model.parse_doc(raw_doc)
object.__setattr__(instance, "__fields_modified__", set())
return instance
def __await__(self) -> Generator[None, None, List[ModelType]]:
if self._results is not None:
return self._results
raw_docs = yield from self._motor_cursor.to_list(length=None).__await__()
instances = []
for raw_doc in raw_docs:
instances.append(self._parse_document(raw_doc))
yield
self._results = instances
return instances
async def __aiter__(self) -> AsyncGenerator[ModelType, None]:
if self._results is not None:
for res in self._results:
yield res
return
results = []
async for raw_doc in self._motor_cursor:
instance = self._parse_document(raw_doc)
results.append(instance)
yield instance
self._results = results
_FORBIDDEN_DATABASE_CHARACTERS = set(("/", "\\", ".", '"', "$"))
class AIOEngine:
"""The AIOEngine object is responsible for handling database operations with MongoDB
in an asynchronous way using motor.
"""
def __init__(self, motor_client: AsyncIOMotorClient = None, database: str = "test"):
"""Engine constructor.
Args:
motor_client: instance of an AsyncIO motor client. If None, a default one
will be created
database: name of the database to use
<!---
#noqa: DAR401 ValueError
-->
"""
# https://docs.mongodb.com/manual/reference/limits/#naming-restrictions
forbidden_characters = _FORBIDDEN_DATABASE_CHARACTERS.intersection(
set(database)
)
if len(forbidden_characters) > 0:
raise ValueError(
f"database name cannot contain: {' '.join(forbidden_characters)}"
)
if motor_client is None:
motor_client = AsyncIOMotorClient()
self.client = motor_client
self.database_name = database
self.database = motor_client[self.database_name]
def get_collection(self, model: Type[ModelType]) -> AsyncIOMotorCollection:
"""Get the motor collection associated to a Model.
Args:
model: model class
Returns:
the AsyncIO motor collection object
"""
return self.database[model.__collection__]
@staticmethod
def _build_query(*queries: Union[QueryExpression, Dict, bool]) -> QueryExpression:
if len(queries) == 0:
return QueryExpression()
for query in queries:
if isinstance(query, bool):
raise TypeError("cannot build query using booleans")
queries = cast(Tuple[Union[QueryExpression, Dict], ...], queries)
if len(queries) == 1:
return QueryExpression(queries[0])
return and_(*queries)
@staticmethod
def _cascade_find_pipeline(
model: Type[ModelType], doc_namespace: str = ""
) -> List[Dict]:
"""Recursively build the find pipeline for model."""
pipeline: List[Dict] = []
for ref_field_name in model.__references__:
odm_reference = cast(ODMReference, model.__odm_fields__[ref_field_name])
pipeline.extend(
[
{
"$lookup": {
"from": odm_reference.model.__collection__,
"let": {"foreign_id": f"${odm_reference.key_name}"},
"pipeline": [
{
"$match": {
"$expr": {"$eq": ["$_id", "$$foreign_id"]}
}
},
*AIOEngine._cascade_find_pipeline(
odm_reference.model,
doc_namespace=f"{doc_namespace}{ref_field_name}.",
),
],
"as": odm_reference.key_name
# FIXME if ref field name is an existing key_name ?
}
},
{ # Preserves document with unbound references
"$unwind": {
"path": f"${odm_reference.key_name}",
"preserveNullAndEmptyArrays": True,
}
},
]
)
return pipeline
@staticmethod
def _build_sort_expression(
sort_field: Union[FieldProxy, SortExpression]
) -> SortExpression:
return (
SortExpression({+sort_field: 1})
if not isinstance(sort_field, SortExpression)
else sort_field
)
@classmethod
def _validate_sort_argument(cls, sort: Any) -> Optional[SortExpression]:
if sort is None:
return None
if isinstance(sort, tuple):
for sorted_field in sort:
if not isinstance(sorted_field, (FieldProxy, SortExpression)):
raise TypeError(
"sort elements have to be Model fields or asc, desc descriptors"
)
sort_expression: Dict = {}
for sort_field in sort:
sort_expression.update(cls._build_sort_expression(sort_field))
return SortExpression(sort_expression)
if not isinstance(sort, (FieldProxy, SortExpression)):
raise TypeError(
"sort has to be a Model field or "
"asc, desc descriptors or a tuple of these"
)
return cls._build_sort_expression(sort)
def find(
self,
model: Type[ModelType],
*queries: Union[
QueryExpression, Dict, bool
], # bool: allow using binary operators with mypy
sort: Optional[Any] = None,
skip: int = 0,
limit: Optional[int] = None,
) -> AIOCursor[ModelType]:
"""Search for Model instances matching the query filter provided
Args:
model: model to perform the operation on
queries: query filter to apply
sort: sort expression
skip: number of document to skip
limit: maximum number of instance fetched
Raises:
DocumentParsingError: unable to parse one of the resulting documents
Returns:
[odmantic.engine.AIOCursor][] of the query
<!---
#noqa: DAR401 ValueError
#noqa: DAR401 TypeError
#noqa: DAR402 DocumentParsingError
-->
"""
if not lenient_issubclass(model, Model):
raise TypeError("Can only call find with a Model class")
sort_expression = self._validate_sort_argument(sort)
if limit is not None and limit <= 0:
raise ValueError("limit has to be a strict positive value or None")
if skip < 0:
raise ValueError("skip has to be a positive integer")
query = AIOEngine._build_query(*queries)
collection = self.get_collection(model)
pipeline: List[Dict] = [{"$match": query}]
if sort_expression is not None:
pipeline.append({"$sort": sort_expression})
if skip > 0:
pipeline.append({"$skip": skip})
if limit is not None and limit > 0:
pipeline.append({"$limit": limit})
pipeline.extend(AIOEngine._cascade_find_pipeline(model))
motor_cursor = collection.aggregate(pipeline)
return AIOCursor(model, motor_cursor)
async def find_one(
self,
model: Type[ModelType],
*queries: Union[
QueryExpression, Dict, bool
], # bool: allow using binary operators w/o plugin,
sort: Optional[Any] = None,
) -> Optional[ModelType]:
"""Search for a Model instance matching the query filter provided
Args:
model: model to perform the operation on
queries: query filter to apply
sort: sort expression
Raises:
DocumentParsingError: unable to parse the resulting document
Returns:
the fetched instance if found otherwise None
<!---
#noqa: DAR401 TypeError
#noqa: DAR402 DocumentParsingError
-->
"""
if not lenient_issubclass(model, Model):
raise TypeError("Can only call find_one with a Model class")
results = await self.find(model, *queries, sort=sort, limit=1)
if len(results) == 0:
return None
return results[0]
async def _save(
self, instance: ModelType, session: AsyncIOMotorClientSession
) -> ModelType:
"""Perform an atomic save operation in the specified session"""
save_tasks = []
for ref_field_name in instance.__references__:
sub_instance = cast(Model, getattr(instance, ref_field_name))
save_tasks.append(self._save(sub_instance, session))
await gather(*save_tasks)
fields_to_update = (
instance.__fields_modified__ | instance.__mutable_fields__
) - set([instance.__primary_field__])
if len(fields_to_update) > 0:
doc = instance.doc(include=fields_to_update)
collection = self.get_collection(type(instance))
await collection.update_one(
{"_id": getattr(instance, instance.__primary_field__)},
{"$set": doc},
upsert=True,
)
return instance
async def save(self, instance: ModelType) -> ModelType:
"""Persist an instance to the database
This method behaves as an 'upsert' operation. If a document already exists
with the same primary key, it will be overwritten.
All the other models referenced by this instance will be saved as well.
Args:
instance: instance to persist
Returns:
the saved instance
NOTE:
The save operation actually modify the instance argument in place. However,
the instance is still returned for convenience.
<!---
#noqa: DAR401 TypeError
-->
"""
if not isinstance(instance, Model):
raise TypeError("Can only call find_one with a Model class")
async with await self.client.start_session() as s:
async with s.start_transaction():
await self._save(instance, s)
object.__setattr__(instance, "__fields_modified__", set())
return instance
async def save_all(self, instances: Sequence[ModelType]) -> List[ModelType]:
"""Persist instances to the database
This method behaves as multiple 'upsert' operations. If one of the document
already exists with the same primary key, it will be overwritten.
All the other models referenced by this instance will be recursively saved as
well.
Args:
instances: instances to persist
Returns:
the saved instances
NOTE:
The save_all operation actually modify the arguments in place. However, the
instances are still returned for convenience.
"""
async with await self.client.start_session() as s:
async with s.start_transaction():
added_instances = await asyncio.gather(
*[self._save(instance, s) for instance in instances]
)
return added_instances
async def delete(self, instance: ModelType) -> None:
"""Delete an instance from the database
Args:
instance: the instance to delete
Raises:
DocumentNotFoundError: the instance has not been persisted to the database
"""
# TODO handle cascade deletion
collection = self.database[instance.__collection__]
pk_name = instance.__primary_field__
result = await collection.delete_many({"_id": getattr(instance, pk_name)})
count = int(result.deleted_count)
if count == 0:
raise DocumentNotFoundError(instance)
async def count(
self, model: Type[ModelType], *queries: Union[QueryExpression, Dict, bool]
) -> int:
"""Get the count of documents matching a query
Args:
model: model to perform the operation on
queries: query filters to apply
Returns:
number of document matching the query
<!---
#noqa: DAR401 TypeError
-->
"""
if not lenient_issubclass(model, Model):
raise TypeError("Can only call count with a Model class")
query = AIOEngine._build_query(*queries)
collection = self.database[model.__collection__]
count = await collection.count_documents(query)
return int(count)