Re: Feature - choices

[Jacques Naude]

Looks super cool to me, and very Elixir-friendly!




Thanks for sharing and providing more insight.

Jacques

Ted Pollari wrote:

Thanks, I'll try it out. (I hope Jonas, the subject originator, also benefits from this.)

On Jul 19, 2007, at 3:05 PM, Jacques Naude wrote:

Having tried Django some time ago, I already had a set of such tuple constants, which I wanted to simply reuse in Elixir. I did think that an enum column type in Elixir would be very handy (like a tried in a version using SQLObject) to have though. One can probably pick it up from the lower SQLAlchemy somehow, but I have no idea how to tackle it at that level without going the whole SQLAlchemy route, which I didn't - I reallt like the look and feel of Elixir.

#############
"""enum.py"""

from elixir import *
from sqlalchemy import types

class Enum(TypeDecorator):

     ENUM column type in MySQL"""

     impl = types.Unicode
     def __init__(self, values, empty_to_none=False):
         '''
         contruct an Enum type

         values : a list of values that are valid for this column
         empty_to_none : treat the empty string '' as None
         '''
         if values is None or len(values) is 0:

         self.empty_to_none = empty_to_none
         self.values = values

         # in values
         size = max([len(v) for v in values if v is not None])
         super(Enum, self).__init__(size)


     def convert_bind_param(self, value, engine):
         if self.empty_to_none and value is '':
             value = None
         if value not in self.values:
             raise AssertionError('"%s" not in Enum.values' % value)

         return super(Enum, self).convert_bind_param(value, engine)


     def convert_result_value(self, value, engine):
         if value not in self.values:
             raise AssertionError('"%s" not in Enum.values' % value)

         return super(Enum, self).convert_result_value(value, engine)

#############





#############
"""test_enum.py"""

from sqlalchemy import create_engine
from enum import *

engine = create_engine('sqlite:///')
metadata.connect(engine)

def test_enum():
     class TestPerson(Entity):

         with_fields(
             gender = Field(Enum(["m","f"])))


     create_all()

     t = TestPerson()
     t.gender = "m"
     objectstore.flush()
     t.gender = "f"
     objectstore.flush()

     try:
         t.gender = "W"  #this should fail
         objectstore.flush()
     except AssertionError:
         pass
     else:


     drop_all()
     objectstore.clear()


#############




-ted




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I have no idea if I'm on a daft path with this -- I'm very new to Elixir and SA -- well, new to enlightened DB programming in any real sense...up to this point, I've used DB's only as simple, persistent data stores with nothing fancy and no real smarts to the implementation, so like I said, I don't know if I'm doing something silly, but here's what I do... We're starting to work on a project with Elixir where we'll need enum types like MySQL has (I've used MySQL a bit for other work, so I got used to using enum cols)... so this is what I came up with, cobbled together primarily from an SA recipe I found out on the web (in other words, I take little credit for it, but am glad to share if it's useful)... """This class adds support for ENUM fields, similar in functionality to the raise exceptions.AssertionError('Enum requires a list of values') # the length of the string/unicode column should be the longest string and then a test to show that it'll fail if you try to use something not in it's values list: assert False #make sure this fails if it doesn't raise the exception above Is that Elixir friendly enough for your needs or have I completely missed the boat here?

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