पायथन के प्रगणित प्रकार SQLAlchemy 1.1 के रूप में SQLAlchemy Enum प्रकार से सीधे स्वीकार्य हैं:
import enum
class MyEnum(enum.Enum):
one = 1
two = 2
three = 3
class MyClass(Base):
__tablename__ = 'some_table'
id = Column(Integer, primary_key=True)
value = Column(Enum(MyEnum))
ध्यान दें कि ऊपर, स्ट्रिंग मान "एक", "दो", "तीन" कायम कर रहे हैं, नहीं पूर्णांक मान
SQLAlchemy के पुराने संस्करणों के लिए, मैं एक पोस्ट जो अपनी ही प्रगणित प्रकार (http://techspot.zzzeek.org/2011/01/14/the-enum-recipe/)
from sqlalchemy.types import SchemaType, TypeDecorator, Enum
from sqlalchemy import __version__
import re
if __version__ < '0.6.5':
raise NotImplementedError("Version 0.6.5 or higher of SQLAlchemy is required.")
class EnumSymbol(object):
"""Define a fixed symbol tied to a parent class."""
def __init__(self, cls_, name, value, description):
self.cls_ = cls_
self.name = name
self.value = value
self.description = description
def __reduce__(self):
"""Allow unpickling to return the symbol
linked to the DeclEnum class."""
return getattr, (self.cls_, self.name)
def __iter__(self):
return iter([self.value, self.description])
def __repr__(self):
return "<%s>" % self.name
class EnumMeta(type):
"""Generate new DeclEnum classes."""
def __init__(cls, classname, bases, dict_):
cls._reg = reg = cls._reg.copy()
for k, v in dict_.items():
if isinstance(v, tuple):
sym = reg[v[0]] = EnumSymbol(cls, k, *v)
setattr(cls, k, sym)
return type.__init__(cls, classname, bases, dict_)
def __iter__(cls):
return iter(cls._reg.values())
class DeclEnum(object):
"""Declarative enumeration."""
__metaclass__ = EnumMeta
_reg = {}
@classmethod
def from_string(cls, value):
try:
return cls._reg[value]
except KeyError:
raise ValueError(
"Invalid value for %r: %r" %
(cls.__name__, value)
)
@classmethod
def values(cls):
return cls._reg.keys()
@classmethod
def db_type(cls):
return DeclEnumType(cls)
class DeclEnumType(SchemaType, TypeDecorator):
def __init__(self, enum):
self.enum = enum
self.impl = Enum(
*enum.values(),
name="ck%s" % re.sub(
'([A-Z])',
lambda m:"_" + m.group(1).lower(),
enum.__name__)
)
def _set_table(self, table, column):
self.impl._set_table(table, column)
def copy(self):
return DeclEnumType(self.enum)
def process_bind_param(self, value, dialect):
if value is None:
return None
return value.value
def process_result_value(self, value, dialect):
if value is None:
return None
return self.enum.from_string(value.strip())
if __name__ == '__main__':
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, create_engine
from sqlalchemy.orm import Session
Base = declarative_base()
class EmployeeType(DeclEnum):
part_time = "P", "Part Time"
full_time = "F", "Full Time"
contractor = "C", "Contractor"
class Employee(Base):
__tablename__ = 'employee'
id = Column(Integer, primary_key=True)
name = Column(String(60), nullable=False)
type = Column(EmployeeType.db_type())
def __repr__(self):
return "Employee(%r, %r)" % (self.name, self.type)
e = create_engine('sqlite://', echo=True)
Base.metadata.create_all(e)
sess = Session(e)
sess.add_all([
Employee(name='e1', type=EmployeeType.full_time),
Employee(name='e2', type=EmployeeType.full_time),
Employee(name='e3', type=EmployeeType.part_time),
Employee(name='e4', type=EmployeeType.contractor),
Employee(name='e5', type=EmployeeType.contractor),
])
sess.commit()
print sess.query(Employee).filter_by(type=EmployeeType.contractor).all()
दूसरा लिंक अब और नहीं खोल रहा है – MajesticRa
@MajesticRa: टिप के लिए धन्यवाद, मैंने लिंक हटा दिया है। वैसे भी यह प्रासंगिक नहीं है। प्रत्येक व्यक्ति को 0.6 साल पहले अपग्रेड करना चाहिए था;) – Wolph