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smartquery.py
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smartquery.py
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try:
# noinspection PyUnresolvedReferences
from typing import List
except ImportError: # pragma: no cover
pass
from collections import abc, OrderedDict
from sqlalchemy import asc, desc, inspect
from sqlalchemy.orm import aliased, contains_eager
from sqlalchemy.orm.util import AliasedClass
from sqlalchemy.sql import operators, extract
# noinspection PyProtectedMember
from .eagerload import EagerLoadMixin, _eager_expr_from_schema
from .inspection import InspectionMixin
from .utils import classproperty
RELATION_SPLITTER = '___'
OPERATOR_SPLITTER = '__'
DESC_PREFIX = '-'
def _flatten_filter_keys(filters):
"""
:type filters: dict|list
Flatten the nested filters, extracting keys where they correspond
to smart_query paths, e.g.
{or_: {'id__gt': 1000, and_ : {
'id__lt': 500,
'related___property__in': (1,2,3)
}}}
Yields:
'id__gt', 'id__lt', 'related___property__in'
Also allow lists (any abc.Sequence subclass) to enable support
of expressions like.
(X OR Y) AND (W OR Z)
{ and_: [
{or_: {'id__gt': 5, 'related_id__lt': 10}},
{or_: {'related_id2__gt': 1, 'name__like': 'Bob' }}
]}
"""
if isinstance(filters, abc.Mapping):
for key, value in filters.items():
if callable(key):
yield from _flatten_filter_keys(value)
else:
yield key
elif isinstance(filters, abc.Sequence):
for f in filters:
yield from _flatten_filter_keys(f)
else:
raise TypeError(
"Unsupported type (%s) in filters: %r", (type(filters), filters)
)
def _parse_path_and_make_aliases(entity, entity_path, attrs, aliases):
"""
:type entity: InspectionMixin
:type entity_path: str
:type attrs: list
:type aliases: OrderedDict
Sample values:
attrs: ['product__subject_ids', 'user_id', '-group_id',
'user__name', 'product__name', 'product__grade_from__order']
relations: {'product': ['subject_ids', 'name'], 'user': ['name']}
"""
relations = {}
# take only attributes that have magic RELATION_SPLITTER
for attr in attrs:
# from attr (say, 'product__grade__order') take
# relationship name ('product') and nested attribute ('grade__order')
if RELATION_SPLITTER in attr:
relation_name, nested_attr = attr.split(RELATION_SPLITTER, 1)
if relation_name in relations:
relations[relation_name].append(nested_attr)
else:
relations[relation_name] = [nested_attr]
for relation_name, nested_attrs in relations.items():
path = (
entity_path + RELATION_SPLITTER + relation_name
if entity_path
else relation_name
)
if relation_name not in entity.relations:
raise KeyError(
"Incorrect path `{}`: "
"{} doesnt have `{}` relationship ".format(path, entity, relation_name)
)
relationship = getattr(entity, relation_name)
alias = aliased(relationship.property.mapper.class_)
aliases[path] = alias, relationship
_parse_path_and_make_aliases(alias, path, nested_attrs, aliases)
def _get_root_cls(query):
# sqlalchemy < 1.4.0
if hasattr(query, '_entity_zero'):
return query._entity_zero().class_
# sqlalchemy >= 1.4.0
else:
if hasattr(query, '_entity_from_pre_ent_zero'):
return query._entity_from_pre_ent_zero().class_
raise ValueError('Cannot get a root class from`{}`'
.format(query))
def smart_query(query, filters=None, sort_attrs=None, schema=None):
"""
Does magic Django-ish joins like post___user___name__startswith='Bob'
(see https://goo.gl/jAgCyM)
Does filtering, sorting and eager loading at the same time.
And if, say, filters and sorting need the same joinm it will be done
only one. That's why all stuff is combined in single method
:param query: sqlalchemy.orm.query.Query
:param filters: dict
:param sort_attrs: List[basestring]
:param schema: dict
"""
if not filters:
filters = {}
if not sort_attrs:
sort_attrs = []
# sqlalchemy >= 1.4.0, should probably a. check something else to determine if we need to convert
# AppenderQuery to a query, b. probably not hack it like this
# noinspection PyProtectedMember
if type(query).__name__ == 'AppenderQuery' and query._statement:
sess = query.session
# noinspection PyProtectedMember
query = query._statement
query.session = sess
root_cls = _get_root_cls(query) # for example, User or Post
attrs = list(_flatten_filter_keys(filters)) + \
list(map(lambda s: s.lstrip(DESC_PREFIX), sort_attrs))
aliases = OrderedDict({})
_parse_path_and_make_aliases(root_cls, '', attrs, aliases)
loaded_paths = []
for path, al in aliases.items():
relationship_path = path.replace(RELATION_SPLITTER, '.')
query = query.outerjoin(al[0], al[1])
loaded_paths.append(relationship_path)
def recurse_filters(_filters):
if isinstance(_filters, abc.Mapping):
for attr, value in _filters.items():
if callable(attr):
# E.g. or_, and_, or other sqlalchemy expression
yield attr(*recurse_filters(value))
continue
if RELATION_SPLITTER in attr:
parts = attr.rsplit(RELATION_SPLITTER, 1)
entity, attr_name = aliases[parts[0]][0], parts[1]
else:
entity, attr_name = root_cls, attr
try:
yield from entity.filter_expr(**{attr_name: value})
except KeyError as e:
raise KeyError("Incorrect filter path `{}`: {}".format(attr, e))
elif isinstance(_filters, abc.Sequence):
for f in _filters:
yield from recurse_filters(f)
query = query.filter(*recurse_filters(filters))
for attr in sort_attrs:
if RELATION_SPLITTER in attr:
prefix = ''
if attr.startswith(DESC_PREFIX):
prefix = DESC_PREFIX
attr = attr.lstrip(DESC_PREFIX)
parts = attr.rsplit(RELATION_SPLITTER, 1)
entity, attr_name = aliases[parts[0]][0], prefix + parts[1]
else:
entity, attr_name = root_cls, attr
try:
query = query.order_by(*entity.order_expr(attr_name))
except KeyError as e:
raise KeyError("Incorrect order path `{}`: {}".format(attr, e))
if schema:
query = query.options(*_eager_expr_from_schema(schema))
return query
class SmartQueryMixin(InspectionMixin, EagerLoadMixin):
__abstract__ = True
_operators = {
'isnull': lambda c, v: (c == None) if v else (c != None),
'exact': operators.eq,
'ne': operators.ne, # not equal or is not (for None)
'gt': operators.gt, # greater than , >
'ge': operators.ge, # greater than or equal, >=
'lt': operators.lt, # lower than, <
'le': operators.le, # lower than or equal, <=
'in': operators.in_op,
'notin': operators.notin_op,
'between': lambda c, v: c.between(v[0], v[1]),
'like': operators.like_op,
'ilike': operators.ilike_op,
'startswith': operators.startswith_op,
'istartswith': lambda c, v: c.ilike(v + '%'),
'endswith': operators.endswith_op,
'iendswith': lambda c, v: c.ilike('%' + v),
'contains': lambda c, v: c.ilike('%{v}%'.format(v=v)),
'year': lambda c, v: extract('year', c) == v,
'year_ne': lambda c, v: extract('year', c) != v,
'year_gt': lambda c, v: extract('year', c) > v,
'year_ge': lambda c, v: extract('year', c) >= v,
'year_lt': lambda c, v: extract('year', c) < v,
'year_le': lambda c, v: extract('year', c) <= v,
'month': lambda c, v: extract('month', c) == v,
'month_ne': lambda c, v: extract('month', c) != v,
'month_gt': lambda c, v: extract('month', c) > v,
'month_ge': lambda c, v: extract('month', c) >= v,
'month_lt': lambda c, v: extract('month', c) < v,
'month_le': lambda c, v: extract('month', c) <= v,
'day': lambda c, v: extract('day', c) == v,
'day_ne': lambda c, v: extract('day', c) != v,
'day_gt': lambda c, v: extract('day', c) > v,
'day_ge': lambda c, v: extract('day', c) >= v,
'day_lt': lambda c, v: extract('day', c) < v,
'day_le': lambda c, v: extract('day', c) <= v,
}
@classproperty
def filterable_attributes(cls):
return cls.relations + cls.columns + \
cls.hybrid_properties + cls.hybrid_methods
@classproperty
def sortable_attributes(cls):
return cls.columns + cls.hybrid_properties
@classmethod
def filter_expr(cls_or_alias, **filters):
"""
forms expressions like [Product.age_from = 5,
Product.subject_ids.in_([1,2])]
from filters like {'age_from': 5, 'subject_ids__in': [1,2]}
Example 1:
db.query(Product).filter(
*Product.filter_expr(age_from = 5, subject_ids__in=[1, 2]))
Example 2:
filters = {'age_from': 5, 'subject_ids__in': [1,2]}
db.query(Product).filter(*Product.filter_expr(**filters))
### About alias ###:
If we will use alias:
alias = aliased(Product) # table name will be product_1
we can't just write query like
db.query(alias).filter(*Product.filter_expr(age_from=5))
because it will be compiled to
SELECT * FROM product_1 WHERE product.age_from=5
which is wrong: we select from 'product_1' but filter on 'product'
such filter will not work
We need to obtain
SELECT * FROM product_1 WHERE product_1.age_from=5
For such case, we can call filter_expr ON ALIAS:
alias = aliased(Product)
db.query(alias).filter(*alias.filter_expr(age_from=5))
Alias realization details:
* we allow to call this method
either ON ALIAS (say, alias.filter_expr())
or on class (Product.filter_expr())
* when method is called on alias, we need to generate SQL using
aliased table (say, product_1), but we also need to have a real
class to call methods on (say, Product.relations)
* so, we have 'mapper' that holds table name
and 'cls' that holds real class
when we call this method ON ALIAS, we will have:
mapper = <product_1 table>
cls = <Product>
when we call this method ON CLASS, we will simply have:
mapper = <Product> (or we could write <Product>.__mapper__.
It doesn't matter because when we call
<Product>.getattr, SA will magically
call <Product>.__mapper__.getattr())
cls = <Product>
"""
if isinstance(cls_or_alias, AliasedClass):
mapper, cls = cls_or_alias, inspect(cls_or_alias).mapper.class_
else:
mapper = cls = cls_or_alias
expressions = []
valid_attributes = cls.filterable_attributes
for attr, value in filters.items():
# if attribute is filtered by method, call this method
if attr in cls.hybrid_methods:
method = getattr(cls, attr)
expressions.append(method(value, mapper=mapper))
# else just add simple condition (== for scalars or IN for lists)
else:
# determine attrbitute name and operator
# if they are explicitly set (say, id___between), take them
if OPERATOR_SPLITTER in attr:
attr_name, op_name = attr.rsplit(OPERATOR_SPLITTER, 1)
if op_name not in cls._operators:
raise KeyError('Expression `{}` has incorrect '
'operator `{}`'.format(attr, op_name))
op = cls._operators[op_name]
# assume equality operator for other cases (say, id=1)
else:
attr_name, op = attr, operators.eq
if attr_name not in valid_attributes:
raise KeyError('Expression `{}` '
'has incorrect attribute `{}`'
.format(attr, attr_name))
column = getattr(mapper, attr_name)
expressions.append(op(column, value))
return expressions
@classmethod
def order_expr(cls_or_alias, *columns):
"""
Forms expressions like [desc(User.first_name), asc(User.phone)]
from list like ['-first_name', 'phone']
Example for 1 column:
db.query(User).order_by(*User.order_expr('-first_name'))
# will compile to ORDER BY user.first_name DESC
Example for multiple columns:
columns = ['-first_name', 'phone']
db.query(User).order_by(*User.order_expr(*columns))
# will compile to ORDER BY user.first_name DESC, user.phone ASC
About cls_or_alias, mapper, cls: read in filter_expr method description
"""
if isinstance(cls_or_alias, AliasedClass):
mapper, cls = cls_or_alias, inspect(cls_or_alias).mapper.class_
else:
mapper = cls = cls_or_alias
expressions = []
for attr in columns:
fn, attr = (desc, attr[1:]) if attr.startswith(DESC_PREFIX) \
else (asc, attr)
if attr not in cls.sortable_attributes:
raise KeyError('Cant order {} by {}'.format(cls, attr))
expr = fn(getattr(mapper, attr))
expressions.append(expr)
return expressions
@classmethod
def smart_query(cls, filters=None, sort_attrs=None, schema=None):
"""
Does magic Django-ish joins like post___user___name__startswith='Bob'
(see https://goo.gl/jAgCyM)
Does filtering, sorting and eager loading at the same time.
And if, say, filters and sorting need the same joinm it will be done
only one. That's why all stuff is combined in single method
:param filters: dict
:param sort_attrs: List[basestring]
:param schema: dict
"""
return smart_query(cls.query, filters, sort_attrs, schema)
@classmethod
def where(cls, **filters):
"""
Shortcut for smart_query() method
Example 1:
Product.where(subject_ids__in=[1,2], grade_from_id=2).all()
Example 2:
filters = {'subject_ids__in': [1,2], 'grade_from_id': 2}
Product.where(**filters).all()
Example 3 (with joins):
Post.where(public=True, user___name__startswith='Bi').all()
"""
return cls.smart_query(filters)
@classmethod
def sort(cls, *columns):
"""
Shortcut for smart_query() method
Example 1:
User.sort('first_name','-user_id')
This is equal to
db.query(User).order_by(*User.order_expr('first_name','-user_id'))
Example 2:
columns = ['first_name','-user_id']
User.sort(*columns)
This is equal to
columns = ['first_name','-user_id']
db.query(User).order_by(*User.order_expr(*columns))
Exanple 3 (with joins):
Post.sort('comments___rating', 'user___name').all()
"""
return cls.smart_query({}, columns)