Question

Instead of using django’s auth module I’ve used my own and already regret it a lot.

In an effort to rectify the situation, I’m trying to migrate the data from my User model to django.auth.models.User.

I’ve created a data migration as follows:

def forwards(self, orm):
    """Migrate user information from mooi User model to auth User model."""

    OldUser = orm['mooi.User']
    User = orm['auth.User']
    Profile = orm['mooi.Profile']

    oldUsers = OldUser.objects.all()
    for oldUser in oldUsers:
        newUser = User.objects.create_user(username=oldUser.id, email=oldUser.email, password=oldUser.password)
        # ...more irrelevant code follows...

When I run the migration, I get this error (traceback):

#...irrelevant traceback precedes...
File "[projdir]/mooi/migrations/0005_from_mooi_users_create_auth_users_with_profiles.py", line 18, in forwards
    newUser = User.objects.create_user(username=oldUser.id, email=oldUser.email, password=oldUser.password)
  File "[virtual_env_dir]lib/python2.6/site-packages/south/orm.py", line 397, in __getattr__
    return getattr(self.real, name)
AttributeError: 'Manager' object has no attribute 'create_user'

Upon further investigation, I discovered that the Manager that was being referred to was of time south.orm.NoDryRunManager which explains the error.

Now, the reason I even need create_user is to create a password hash that django.contrib.auth will understand.

Having said all that, how do I go about doing this? What’s the most elegant solution given the hole I’m in?!

Thanks in advance.

Update 1

As suggested by stevejalim, I tried to use User‘s set_password(...) as follows:

newUser.set_password(raw_password=oldUser.password)
newUser.save()

However that failed with this error:

File "[projdir]/mooi/migrations/0005_from_mooi_users_create_auth_users_with_profiles.py", line 21, in forwards
    newUser.set_password(raw_password=oldUser.password)
AttributeError: 'User' object has no attribute 'set_password'

I did find a hint in the south documentation which states that:

South doesn’t freeze every aspect of a
model; for example, it doesn’t
preserve new managers, or custom model
methods, as these would require
serialising the python code that runs
those method (and the code that
depends on, and so forth).

If you want custom methods in your
migration, you’ll have to copy the
code in, including any imports it
relies on to work. Remember, however,
for every import that you add, you’re
promising to keep that import valid
for the life for the migration.

I guess the question remains, what’s the best/safest way of doing this? Copy the set_password(...) method over? Create a function that hashes the password for me? Any other ideas?

Answer 1

Ok, it turns out that South doesn’t freeze methods at all, so calling any model methods is of no use.

The way I solved this was by coping and modifying the code in contrib.auth that generates passwords.

Here’s how the final migration looks like:

# encoding: utf-8
import datetime
from south.db import db
from south.v2 import DataMigration
from django.db import models

class Promise(object):
    """
    This is just a base class for the proxy class created in
    the closure of the lazy function. It can be used to recognize
    promises in code.
    """
    pass

def lazy(func, *resultclasses):
    """
    Turns any callable into a lazy evaluated callable. You need to give result
    classes or types -- at least one is needed so that the automatic forcing of
    the lazy evaluation code is triggered. Results are not memoized; the
    function is evaluated on every access.
    """

    class __proxy__(Promise):
        """
        Encapsulate a function call and act as a proxy for methods that are
        called on the result of that function. The function is not evaluated
        until one of the methods on the result is called.
        """
        __dispatch = None

        def __init__(self, args, kw):
            self.__func = func
            self.__args = args
            self.__kw = kw
            if self.__dispatch is None:
                self.__prepare_class__()

        def __reduce__(self):
            return (
                _lazy_proxy_unpickle,
                (self.__func, self.__args, self.__kw) + resultclasses
            )

        def __prepare_class__(cls):
            cls.__dispatch = {}
            for resultclass in resultclasses:
                cls.__dispatch[resultclass] = {}
                for (k, v) in resultclass.__dict__.items():
                    # All __promise__ return the same wrapper method, but they
                    # also do setup, inserting the method into the dispatch
                    # dict.
                    meth = cls.__promise__(resultclass, k, v)
                    if hasattr(cls, k):
                        continue
                    setattr(cls, k, meth)
            cls._delegate_str = str in resultclasses
            cls._delegate_unicode = unicode in resultclasses
            assert not (cls._delegate_str and cls._delegate_unicode), "Cannot call lazy() with both str and unicode return types."
            if cls._delegate_unicode:
                cls.__unicode__ = cls.__unicode_cast
            elif cls._delegate_str:
                cls.__str__ = cls.__str_cast
        __prepare_class__ = classmethod(__prepare_class__)

        def __promise__(cls, klass, funcname, func):
            # Builds a wrapper around some magic method and registers that magic
            # method for the given type and method name.
            def __wrapper__(self, *args, **kw):
                # Automatically triggers the evaluation of a lazy value and
                # applies the given magic method of the result type.
                res = self.__func(*self.__args, **self.__kw)
                for t in type(res).mro():
                    if t in self.__dispatch:
                        return self.__dispatch[t][funcname](res, *args, **kw)
                raise TypeError("Lazy object returned unexpected type.")

            if klass not in cls.__dispatch:
                cls.__dispatch[klass] = {}
            cls.__dispatch[klass][funcname] = func
            return __wrapper__
        __promise__ = classmethod(__promise__)

        def __unicode_cast(self):
            return self.__func(*self.__args, **self.__kw)

        def __str_cast(self):
            return str(self.__func(*self.__args, **self.__kw))

        def __cmp__(self, rhs):
            if self._delegate_str:
                s = str(self.__func(*self.__args, **self.__kw))
            elif self._delegate_unicode:
                s = unicode(self.__func(*self.__args, **self.__kw))
            else:
                s = self.__func(*self.__args, **self.__kw)
            if isinstance(rhs, Promise):
                return -cmp(rhs, s)
            else:
                return cmp(s, rhs)

        def __mod__(self, rhs):
            if self._delegate_str:
                return str(self) % rhs
            elif self._delegate_unicode:
                return unicode(self) % rhs
            else:
                raise AssertionError('__mod__ not supported for non-string types')

        def __deepcopy__(self, memo):
            # Instances of this class are effectively immutable. It's just a
            # collection of functions. So we don't need to do anything
            # complicated for copying.
            memo[id(self)] = self
            return self

    def __wrapper__(*args, **kw):
        # Creates the proxy object, instead of the actual value.
        return __proxy__(args, kw)

    return wraps(func)(__wrapper__)


# code to encrypt passwords borrowed from django 1.2.1:
def smart_str(s, encoding='utf-8', strings_only=False, errors='strict'):
    """
    Returns a bytestring version of 's', encoded as specified in 'encoding'.

    If strings_only is True, don't convert (some) non-string-like objects.
    """
    if strings_only and isinstance(s, (types.NoneType, int)):
        return s
    if isinstance(s, Promise):
        return unicode(s).encode(encoding, errors)
    elif not isinstance(s, basestring):
        try:
            return str(s)
        except UnicodeEncodeError:
            if isinstance(s, Exception):
                # An Exception subclass containing non-ASCII data that doesn't
                # know how to print itself properly. We shouldn't raise a
                # further exception.
                return ' '.join([smart_str(arg, encoding, strings_only,
                        errors) for arg in s])
            return unicode(s).encode(encoding, errors)
    elif isinstance(s, unicode):
        return s.encode(encoding, errors)
    elif s and encoding != 'utf-8':
        return s.decode('utf-8', errors).encode(encoding, errors)
    else:
        return s

def get_hexdigest(algorithm, salt, raw_password):
    """
    Returns a string of the hexdigest of the given plaintext password and salt
    using the given algorithm ('md5', 'sha1' or 'crypt').
    """
    raw_password, salt = smart_str(raw_password), smart_str(salt)
    if algorithm == 'crypt':
        try:
            import crypt
        except ImportError:
            raise ValueError('"crypt" password algorithm not supported in this environment')
        return crypt.crypt(raw_password, salt)
    # The rest of the supported algorithms are supported by hashlib, but
    # hashlib is only available in Python 2.5.
    try:
        import hashlib
    except ImportError:
        if algorithm == 'md5':
            import md5
            return md5.new(salt + raw_password).hexdigest()
        elif algorithm == 'sha1':
            import sha
            return sha.new(salt + raw_password).hexdigest()
    else:
        if algorithm == 'md5':
            return hashlib.md5(salt + raw_password).hexdigest()
        elif algorithm == 'sha1':
            return hashlib.sha1(salt + raw_password).hexdigest()
    raise ValueError("Got unknown password algorithm type in password.")

def get_encrypted_password(raw_password):
    import random
    algo = 'sha1'
    salt = get_hexdigest(algo, str(random.random()), str(random.random()))[:5]
    hsh = get_hexdigest(algo, salt, raw_password)
    return '%s$%s$%s' % (algo, salt, hsh)


class Migration(DataMigration):

    def forwards(self, orm):
        """Migrate user information from mooi User model to auth User model."""

        OldUser = orm['mooi.User']
        User = orm['auth.User']
        Profile = orm['mooi.Profile']

        oldUsers = OldUser.objects.all()
        for oldUser in oldUsers:
            newUser = User(username=oldUser.id, email=oldUser.email)
            newUser.first_name = oldUser.name
            newUser.save()
            newUser.password = get_encrypted_password(oldUser.password)
            newUser.save()
            newUserProfile = Profile(user=newUser)
            newUserProfile.phone = oldUser.phone
            newUserProfile.credits = oldUser.credits
            newUserProfile.transaction_status = oldUser.transaction_status
            newUserProfile.location = oldUser.location
            newUserProfile.save()
            assert oldUser.id == newUser.username, \
                "Old user: %s, is not equal to: %s" % (oldUser.id, newUser.username)
            assert oldUser.name == newUser.first_name, \
                "Names don't match, old: %s, new: %s" % (oldUser.name, newUser.first_name)
            assert oldUser.email == newUser.email, \
                "Emails don't match, old: %s, new: %s" % (oldUser.email, newUser.email)
            assert oldUser.phone == newUserProfile.phone, \
                "Phones don't match, old: %s, new: %s" % (oldUser.phone, newUserProfile.phone)
            assert oldUser.credits == newUserProfile.credits, \
                "Credits don't match, old: %s, new: %s" % (oldUser.credits, newUserProfile.credits)
            assert oldUser.transaction_status == newUserProfile.transaction_status, \
                "Trans. status don't match, old: %s, new: %s" % (oldUser.transaction_status, newUserProfile.transaction_status)
            assert oldUser.location == newUserProfile.location, \
                "Locations don't match: old: %s, new: %s" % (oldUser.location == newUserProfile.location)