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devicehub-teal/ereuse_devicehub/teal/query.py
2023-03-21 17:31:43 +01:00

295 lines
7.7 KiB
Python

import json
from json import JSONDecodeError
from ereuse_devicehub.ereuse_utils import flatten_mixed
from marshmallow import Schema as MarshmallowSchema
from marshmallow.fields import Boolean, Field, List, Nested, Str, missing_
from sqlalchemy import Column, between, or_
from webargs.flaskparser import FlaskParser
class ListQuery(List):
"""Base class for list-based queries."""
def __init__(self, column: Column, cls_or_instance, **kwargs):
self.column = column
super().__init__(cls_or_instance, **kwargs)
class Between(ListQuery):
"""
Generates a `Between` SQL statement.
This method wants the user to provide exactly two parameters:
min and max::
f = Between(Model.foo, Integer())
...
Query().loads({'f': [0, 100]}
"""
def _deserialize(self, value, attr, data):
l = super()._deserialize(value, attr, data)
return between(self.column, *l)
class Equal(Field):
"""
Generates an SQL equal ``==`` clause for a given column and value::
class MyArgs(Query):
f = Equal(MyModel.foo, Integer())
MyArgs().load({'f': 24}) -> SQL: ``MyModel.foo == 24``
"""
def __init__(
self,
column: Column,
field: Field,
default=missing_,
attribute=None,
data_key=None,
error=None,
validate=None,
required=False,
allow_none=None,
load_only=False,
dump_only=False,
missing=missing_,
error_messages=None,
**metadata,
):
super().__init__(
default,
attribute,
data_key,
error,
validate,
required,
allow_none,
load_only,
dump_only,
missing,
error_messages,
**metadata,
)
self.column = column
self.field = field
def _deserialize(self, value, attr, data):
v = super()._deserialize(value, attr, data)
return self.column == self.field.deserialize(v)
class Or(List):
"""
Generates an `OR` SQL statement. This is like a Marshmallow List field,
so you can specify the type of value of the OR and validations.
As an example, you can define with this a list of options::
f = Or(Equal(Model.foo, Str(validates=OneOf(['option1', 'option2'])))
Where the user can select one or more::
{'f': ['option1']}
And with ``Length`` you can enforce the user to only choose one option::
f = Or(..., validates=Length(equal=1))
"""
def _deserialize(self, value, attr, data):
l = super()._deserialize(value, attr, data)
return or_(v for v in l)
class ILike(Str):
"""
Generates a insensitive `LIKE` statement for strings.
"""
def __init__(
self,
column: Column,
default=missing_,
attribute=None,
data_key=None,
error=None,
validate=None,
required=False,
allow_none=None,
load_only=False,
dump_only=False,
missing=missing_,
error_messages=None,
**metadata,
):
super().__init__(
default,
attribute,
data_key,
error,
validate,
required,
allow_none,
load_only,
dump_only,
missing,
error_messages,
**metadata,
)
self.column = column
def _deserialize(self, value, attr, data):
v = super()._deserialize(value, attr, data)
return self.column.ilike('{}%'.format(v))
class QueryField(Field):
"""A field whose first parameter is a function that when
executed by passing only the value returns a SQLAlchemy query
expression.
"""
def __init__(
self,
query,
field: Field,
default=missing_,
attribute=None,
data_key=None,
error=None,
validate=None,
required=False,
allow_none=None,
load_only=False,
dump_only=False,
missing=missing_,
error_messages=None,
**metadata,
):
super().__init__(
default,
attribute,
data_key,
error,
validate,
required,
allow_none,
load_only,
dump_only,
missing,
error_messages,
**metadata,
)
self.query = query
self.field = field
def _deserialize(self, value, attr, data):
v = super()._deserialize(value, attr, data)
return self.query(v)
class Join(Nested):
# todo Joins are manual: they should be able to use ORM's join
def __init__(
self, join, nested, default=missing_, exclude=tuple(), only=None, **kwargs
):
super().__init__(nested, default, exclude, only, **kwargs)
self.join = join
def _deserialize(self, value, attr, data):
v = list(super()._deserialize(value, attr, data))
v.append(self.join)
return v
class Query(MarshmallowSchema):
"""
A Marshmallow schema that outputs SQLAlchemy queries when ``loading``
dictionaries::
class MyQuery(Query):
foo = Like(Mymodel.foocolumn)
Mymodel.query.filter(*MyQuery().load({'foo': 'bar'})).all()
# Executes query SELECT ... WHERE foocolumn IS LIKE 'bar%'
When used with ``webargs`` library you can pass generate queries
directly from the browser: ``foo.com/foo/?filter={'foo': 'bar'}``.
"""
def load(self, data, many=None, partial=None):
"""
Flatten ``Nested`` ``Query`` and add the list of results to
a SQL ``AND``.
"""
values = super().load(data, many, partial).values()
return flatten_mixed(values)
def dump(self, obj, many=None, update_fields=True):
raise NotImplementedError('Why would you want to dump a query?')
class Sort(MarshmallowSchema):
"""
A Marshmallow schema that outputs SQLAlchemy order clauses::
class MySort(Sort):
foo = SortField(MyModel.foocolumn)
MyModel.query.filter(...).order_by(*MyQuery().load({'foo': 0})).all()
When used with ``webargs`` library you can pass generate sorts
directly from the browser: ``foo.com/foo/?sort={'foo': 1, 'bar': 0}``.
"""
ASCENDING = True
"""Sort in ascending order."""
DESCENDING = False
"""Sort in descending order."""
def load(self, data, many=None, partial=None):
values = super().load(data, many, partial).values()
return flatten_mixed(values)
class SortField(Boolean):
"""A field that outputs a SQLAlchemy order clause."""
def __init__(
self, column: Column, truthy=Boolean.truthy, falsy=Boolean.falsy, **kwargs
):
super().__init__(truthy, falsy, **kwargs)
self.column = column
def _deserialize(self, value, attr, data):
v = super()._deserialize(value, attr, data)
return self.column.asc() if v else self.column.desc()
class NestedQueryFlaskParser(FlaskParser):
"""
Parses JSON-encoded URL parameters like
``.../foo?param={"x": "y"}&param2=["x", "y"]``, and it still allows
normal non-JSON-encoded params ``../foo?param=23&param2={"a": "b"}``.
You can keep a value always a string, regardless if it is a valid
JSON, by overriding the following method and setting per-case
actions by checking `name` property.
"""
def parse_querystring(self, req, name, field):
v = super().parse_querystring(req, name, field)
try:
return json.loads(v)
except (JSONDecodeError, TypeError):
return v
class FullTextSearch(Str):
# todo this is dummy for now
pass