Current File : //opt/alt/python35/lib64/python3.5/site-packages/playhouse/shortcuts.py
import sys
from peewee import *
from peewee import Node
if sys.version_info[0] == 3:
from collections import Callable
callable = lambda c: isinstance(c, Callable)
def case(predicate, expression_tuples, default=None):
"""
CASE statement builder.
Example CASE statements:
SELECT foo,
CASE
WHEN foo = 1 THEN "one"
WHEN foo = 2 THEN "two"
ELSE "?"
END -- will be in column named "case" in postgres --
FROM bar;
-- equivalent to above --
SELECT foo,
CASE foo
WHEN 1 THEN "one"
WHEN 2 THEN "two"
ELSE "?"
END
Corresponding peewee:
# No predicate, use expressions.
Bar.select(Bar.foo, case(None, (
(Bar.foo == 1, "one"),
(Bar.foo == 2, "two")), "?"))
# Predicate, will test for equality.
Bar.select(Bar.foo, case(Bar.foo, (
(1, "one"),
(2, "two")), "?"))
"""
clauses = [SQL('CASE')]
simple_case = predicate is not None
if simple_case:
clauses.append(predicate)
for expr, value in expression_tuples:
# If this is a simple case, each tuple will contain (value, value) pair
# since the DB will be performing an equality check automatically.
# Otherwise, we will have (expression, value) pairs.
clauses.extend((SQL('WHEN'), expr, SQL('THEN'), value))
if default is not None:
clauses.extend((SQL('ELSE'), default))
clauses.append(SQL('END'))
return Clause(*clauses)
def cast(node, as_type):
return fn.CAST(Clause(node, SQL('AS %s' % as_type)))
def _clone_set(s):
if s:
return set(s)
return set()
def model_to_dict(model, recurse=True, backrefs=False, only=None,
exclude=None, seen=None, extra_attrs=None,
fields_from_query=None, max_depth=None):
"""
Convert a model instance (and any related objects) to a dictionary.
:param bool recurse: Whether foreign-keys should be recursed.
:param bool backrefs: Whether lists of related objects should be recursed.
:param only: A list (or set) of field instances indicating which fields
should be included.
:param exclude: A list (or set) of field instances that should be
excluded from the dictionary.
:param list extra_attrs: Names of model instance attributes or methods
that should be included.
:param SelectQuery fields_from_query: Query that was source of model. Take
fields explicitly selected by the query and serialize them.
:param int max_depth: Maximum depth to recurse, value <= 0 means no max.
"""
max_depth = -1 if max_depth is None else max_depth
if max_depth == 0:
recurse = False
only = _clone_set(only)
extra_attrs = _clone_set(extra_attrs)
if fields_from_query is not None:
for item in fields_from_query._select:
if isinstance(item, Field):
only.add(item)
elif isinstance(item, Node) and item._alias:
extra_attrs.add(item._alias)
data = {}
exclude = _clone_set(exclude)
seen = _clone_set(seen)
exclude |= seen
model_class = type(model)
for field in model._meta.declared_fields:
if field in exclude or (only and (field not in only)):
continue
field_data = model._data.get(field.name)
if isinstance(field, ForeignKeyField) and recurse:
if field_data:
seen.add(field)
rel_obj = getattr(model, field.name)
field_data = model_to_dict(
rel_obj,
recurse=recurse,
backrefs=backrefs,
only=only,
exclude=exclude,
seen=seen,
max_depth=max_depth - 1)
else:
field_data = {}
data[field.name] = field_data
if extra_attrs:
for attr_name in extra_attrs:
attr = getattr(model, attr_name)
if callable(attr):
data[attr_name] = attr()
else:
data[attr_name] = attr
if backrefs and recurse:
for related_name, foreign_key in model._meta.reverse_rel.items():
descriptor = getattr(model_class, related_name)
if descriptor in exclude or foreign_key in exclude:
continue
if only and (descriptor not in only) and (foreign_key not in only):
continue
accum = []
exclude.add(foreign_key)
related_query = getattr(
model,
related_name + '_prefetch',
getattr(model, related_name))
for rel_obj in related_query:
accum.append(model_to_dict(
rel_obj,
recurse=recurse,
backrefs=backrefs,
only=only,
exclude=exclude,
max_depth=max_depth - 1))
data[related_name] = accum
return data
def dict_to_model(model_class, data, ignore_unknown=False):
instance = model_class()
meta = model_class._meta
for key, value in data.items():
if key in meta.fields:
field = meta.fields[key]
is_backref = False
elif key in model_class._meta.reverse_rel:
field = meta.reverse_rel[key]
is_backref = True
elif ignore_unknown:
setattr(instance, key, value)
continue
else:
raise AttributeError('Unrecognized attribute "%s" for model '
'class %s.' % (key, model_class))
is_foreign_key = isinstance(field, ForeignKeyField)
if not is_backref and is_foreign_key and isinstance(value, dict):
setattr(
instance,
field.name,
dict_to_model(field.rel_model, value, ignore_unknown))
elif is_backref and isinstance(value, (list, tuple)):
instances = [
dict_to_model(
field.model_class,
row_data,
ignore_unknown)
for row_data in value]
for rel_instance in instances:
setattr(rel_instance, field.name, instance)
setattr(instance, field.related_name, instances)
else:
setattr(instance, field.name, value)
return instance
class RetryOperationalError(object):
def execute_sql(self, sql, params=None, require_commit=True):
try:
cursor = super(RetryOperationalError, self).execute_sql(
sql, params, require_commit)
except OperationalError:
if not self.is_closed():
self.close()
with self.exception_wrapper():
cursor = self.get_cursor()
cursor.execute(sql, params or ())
if require_commit and self.get_autocommit():
self.commit()
return cursor
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