752 lines
27 KiB
Python

#!/usr/bin/env python
# -*- coding: UTF-8 -*-
"""
Title: Dumpscript management command
Project: Hardytools (queryset-refactor version)
Author: Will Hardy (http://willhardy.com.au)
Date: June 2008
Usage: python manage.py dumpscript appname > scripts/scriptname.py
$Revision: 217 $
Description:
Generates a Python script that will repopulate the database using objects.
The advantage of this approach is that it is easy to understand, and more
flexible than directly populating the database, or using XML.
* It also allows for new defaults to take effect and only transfers what is
needed.
* If a new database schema has a NEW ATTRIBUTE, it is simply not
populated (using a default value will make the transition smooth :)
* If a new database schema REMOVES AN ATTRIBUTE, it is simply ignored
and the data moves across safely (I'm assuming we don't want this
attribute anymore.
* Problems may only occur if there is a new model and is now a required
ForeignKey for an existing model. But this is easy to fix by editing the
populate script. Half of the job is already done as all ForeingKey
lookups occur though the locate_object() function in the generated script.
Improvements:
See TODOs and FIXMEs scattered throughout :-)
"""
import sys
import datetime
import six
import django
from django.db.models import AutoField, BooleanField, FileField, ForeignKey
from django.core.exceptions import ObjectDoesNotExist
from django.core.management.base import BaseCommand
# conditional import, force_unicode was renamed in Django 1.5
from django.contrib.contenttypes.models import ContentType
try:
from django.utils.encoding import smart_unicode, force_unicode # NOQA
except ImportError:
from django.utils.encoding import smart_text as smart_unicode, force_text as force_unicode # NOQA
def orm_item_locator(orm_obj):
"""
This function is called every time an object that will not be exported is required.
Where orm_obj is the referred object.
We postpone the lookup to locate_object() which will be run on the generated script
"""
the_class = orm_obj._meta.object_name
original_class = the_class
pk_name = orm_obj._meta.pk.name
original_pk_name = pk_name
pk_value = getattr(orm_obj, pk_name)
while hasattr(pk_value, "_meta") and hasattr(pk_value._meta, "pk") and hasattr(pk_value._meta.pk, "name"):
the_class = pk_value._meta.object_name
pk_name = pk_value._meta.pk.name
pk_value = getattr(pk_value, pk_name)
clean_dict = make_clean_dict(orm_obj.__dict__)
for key in clean_dict:
v = clean_dict[key]
if v is not None and not isinstance(v, (six.string_types, six.integer_types, float, datetime.datetime)):
clean_dict[key] = six.u("%s" % v)
output = """ importer.locate_object(%s, "%s", %s, "%s", %s, %s ) """ % (
original_class, original_pk_name,
the_class, pk_name, pk_value, clean_dict
)
return output
class Command(BaseCommand):
help = 'Dumps the data as a customised python script.'
args = '[appname ...]'
def handle(self, *app_labels, **options):
# Get the models we want to export
models = get_models(app_labels)
# A dictionary is created to keep track of all the processed objects,
# so that foreign key references can be made using python variable names.
# This variable "context" will be passed around like the town bicycle.
context = {}
# Create a dumpscript object and let it format itself as a string
self.stdout.write(str(Script(models=models, context=context, stdout=self.stdout, stderr=self.stderr)))
self.stdout.write("\n")
def get_models(app_labels):
""" Gets a list of models for the given app labels, with some exceptions.
TODO: If a required model is referenced, it should also be included.
Or at least discovered with a get_or_create() call.
"""
from django.db.models import get_app, get_apps, get_model
from django.db.models import get_models as get_all_models
# These models are not to be output, e.g. because they can be generated automatically
# TODO: This should be "appname.modelname" string
EXCLUDED_MODELS = (ContentType, )
models = []
# If no app labels are given, return all
if not app_labels:
for app in get_apps():
models += [m for m in get_all_models(app) if m not in EXCLUDED_MODELS]
# Get all relevant apps
for app_label in app_labels:
# If a specific model is mentioned, get only that model
if "." in app_label:
app_label, model_name = app_label.split(".", 1)
models.append(get_model(app_label, model_name))
# Get all models for a given app
else:
models += [m for m in get_all_models(get_app(app_label)) if m not in EXCLUDED_MODELS]
return models
class Code(object):
""" A snippet of python script.
This keeps track of import statements and can be output to a string.
In the future, other features such as custom indentation might be included
in this class.
"""
def __init__(self, indent=-1, stdout=None, stderr=None):
if not stdout:
stdout = sys.stdout
if not stderr:
stderr = sys.stderr
self.indent = indent
self.stdout = stdout
self.stderr = stderr
def __str__(self):
""" Returns a string representation of this script.
"""
if self.imports:
self.stderr.write(repr(self.import_lines))
return flatten_blocks([""] + self.import_lines + [""] + self.lines, num_indents=self.indent)
else:
return flatten_blocks(self.lines, num_indents=self.indent)
def get_import_lines(self):
""" Takes the stored imports and converts them to lines
"""
if self.imports:
return ["from %s import %s" % (value, key) for key, value in self.imports.items()]
else:
return []
import_lines = property(get_import_lines)
class ModelCode(Code):
" Produces a python script that can recreate data for a given model class. "
def __init__(self, model, context=None, stdout=None, stderr=None):
super(ModelCode, self).__init__(indent=0, stdout=stdout, stderr=stderr)
self.model = model
if context is None:
context = {}
self.context = context
self.instances = []
def get_imports(self):
""" Returns a dictionary of import statements, with the variable being
defined as the key.
"""
return {self.model.__name__: smart_unicode(self.model.__module__)}
imports = property(get_imports)
def get_lines(self):
""" Returns a list of lists or strings, representing the code body.
Each list is a block, each string is a statement.
"""
code = []
for counter, item in enumerate(self.model._default_manager.all()):
instance = InstanceCode(instance=item, id=counter + 1, context=self.context, stdout=self.stdout, stderr=self.stderr)
self.instances.append(instance)
if instance.waiting_list:
code += instance.lines
# After each instance has been processed, try again.
# This allows self referencing fields to work.
for instance in self.instances:
if instance.waiting_list:
code += instance.lines
return code
lines = property(get_lines)
class InstanceCode(Code):
" Produces a python script that can recreate data for a given model instance. "
def __init__(self, instance, id, context=None, stdout=None, stderr=None):
""" We need the instance in question and an id """
super(InstanceCode, self).__init__(indent=0, stdout=stdout, stderr=stderr)
self.imports = {}
self.instance = instance
self.model = self.instance.__class__
if context is None:
context = {}
self.context = context
self.variable_name = "%s_%s" % (self.instance._meta.db_table, id)
self.skip_me = None
self.instantiated = False
self.waiting_list = list(self.model._meta.fields)
self.many_to_many_waiting_list = {}
for field in self.model._meta.many_to_many:
self.many_to_many_waiting_list[field] = list(getattr(self.instance, field.name).all())
def get_lines(self, force=False):
""" Returns a list of lists or strings, representing the code body.
Each list is a block, each string is a statement.
force (True or False): if an attribute object cannot be included,
it is usually skipped to be processed later. With 'force' set, there
will be no waiting: a get_or_create() call is written instead.
"""
code_lines = []
# Don't return anything if this is an instance that should be skipped
if self.skip():
return []
# Initialise our new object
# e.g. model_name_35 = Model()
code_lines += self.instantiate()
# Add each field
# e.g. model_name_35.field_one = 1034.91
# model_name_35.field_two = "text"
code_lines += self.get_waiting_list()
if force:
# TODO: Check that M2M are not affected
code_lines += self.get_waiting_list(force=force)
# Print the save command for our new object
# e.g. model_name_35.save()
if code_lines:
code_lines.append("%s = importer.save_or_locate(%s)\n" % (self.variable_name, self.variable_name))
code_lines += self.get_many_to_many_lines(force=force)
return code_lines
lines = property(get_lines)
def skip(self):
""" Determine whether or not this object should be skipped.
If this model instance is a parent of a single subclassed
instance, skip it. The subclassed instance will create this
parent instance for us.
TODO: Allow the user to force its creation?
"""
if self.skip_me is not None:
return self.skip_me
def get_skip_version():
""" Return which version of the skip code should be run
Django's deletion code was refactored in r14507 which
was just two days before 1.3 alpha 1 (r14519)
"""
if not hasattr(self, '_SKIP_VERSION'):
version = django.VERSION
# no, it isn't lisp. I swear.
self._SKIP_VERSION = (
version[0] > 1 or ( # django 2k... someday :)
version[0] == 1 and ( # 1.x
version[1] >= 4 or # 1.4+
version[1] == 3 and not ( # 1.3.x
(version[3] == 'alpha' and version[1] == 0)
)
)
)
) and 2 or 1 # NOQA
return self._SKIP_VERSION
if get_skip_version() == 1:
try:
# Django trunk since r7722 uses CollectedObjects instead of dict
from django.db.models.query import CollectedObjects
sub_objects = CollectedObjects()
except ImportError:
# previous versions don't have CollectedObjects
sub_objects = {}
self.instance._collect_sub_objects(sub_objects)
sub_objects = sub_objects.keys()
elif get_skip_version() == 2:
from django.db.models.deletion import Collector
from django.db import router
cls = self.instance.__class__
using = router.db_for_write(cls, instance=self.instance)
collector = Collector(using=using)
collector.collect([self.instance], collect_related=False)
# collector stores its instances in two places. I *think* we
# only need collector.data, but using the batches is needed
# to perfectly emulate the old behaviour
# TODO: check if batches are really needed. If not, remove them.
sub_objects = sum([list(i) for i in collector.data.values()], [])
for batch in collector.batches.values():
# batch.values can be sets, which must be converted to lists
sub_objects += sum([list(i) for i in batch.values()], [])
sub_objects_parents = [so._meta.parents for so in sub_objects]
if [self.model in p for p in sub_objects_parents].count(True) == 1:
# since this instance isn't explicitly created, it's variable name
# can't be referenced in the script, so record None in context dict
pk_name = self.instance._meta.pk.name
key = '%s_%s' % (self.model.__name__, getattr(self.instance, pk_name))
self.context[key] = None
self.skip_me = True
else:
self.skip_me = False
return self.skip_me
def instantiate(self):
" Write lines for instantiation "
# e.g. model_name_35 = Model()
code_lines = []
if not self.instantiated:
code_lines.append("%s = %s()" % (self.variable_name, self.model.__name__))
self.instantiated = True
# Store our variable name for future foreign key references
pk_name = self.instance._meta.pk.name
key = '%s_%s' % (self.model.__name__, getattr(self.instance, pk_name))
self.context[key] = self.variable_name
return code_lines
def get_waiting_list(self, force=False):
" Add lines for any waiting fields that can be completed now. "
code_lines = []
# Process normal fields
for field in list(self.waiting_list):
try:
# Find the value, add the line, remove from waiting list and move on
value = get_attribute_value(self.instance, field, self.context, force=force)
code_lines.append('%s.%s = %s' % (self.variable_name, field.name, value))
self.waiting_list.remove(field)
except SkipValue:
# Remove from the waiting list and move on
self.waiting_list.remove(field)
continue
except DoLater:
# Move on, maybe next time
continue
return code_lines
def get_many_to_many_lines(self, force=False):
""" Generates lines that define many to many relations for this instance. """
lines = []
for field, rel_items in self.many_to_many_waiting_list.items():
for rel_item in list(rel_items):
try:
pk_name = rel_item._meta.pk.name
key = '%s_%s' % (rel_item.__class__.__name__, getattr(rel_item, pk_name))
value = "%s" % self.context[key]
lines.append('%s.%s.add(%s)' % (self.variable_name, field.name, value))
self.many_to_many_waiting_list[field].remove(rel_item)
except KeyError:
if force:
item_locator = orm_item_locator(rel_item)
self.context["__extra_imports"][rel_item._meta.object_name] = rel_item.__module__
lines.append('%s.%s.add( %s )' % (self.variable_name, field.name, item_locator))
self.many_to_many_waiting_list[field].remove(rel_item)
if lines:
lines.append("")
return lines
class Script(Code):
" Produces a complete python script that can recreate data for the given apps. "
def __init__(self, models, context=None, stdout=None, stderr=None):
super(Script, self).__init__(stdout=stdout, stderr=stderr)
self.imports = {}
self.models = models
if context is None:
context = {}
self.context = context
self.context["__avaliable_models"] = set(models)
self.context["__extra_imports"] = {}
def _queue_models(self, models, context):
""" Works an an appropriate ordering for the models.
This isn't essential, but makes the script look nicer because
more instances can be defined on their first try.
"""
# Max number of cycles allowed before we call it an infinite loop.
MAX_CYCLES = 5
model_queue = []
number_remaining_models = len(models)
allowed_cycles = MAX_CYCLES
while number_remaining_models > 0:
previous_number_remaining_models = number_remaining_models
model = models.pop(0)
# If the model is ready to be processed, add it to the list
if check_dependencies(model, model_queue, context["__avaliable_models"]):
model_class = ModelCode(model=model, context=context, stdout=self.stdout, stderr=self.stderr)
model_queue.append(model_class)
# Otherwise put the model back at the end of the list
else:
models.append(model)
# Check for infinite loops.
# This means there is a cyclic foreign key structure
# That cannot be resolved by re-ordering
number_remaining_models = len(models)
if number_remaining_models == previous_number_remaining_models:
allowed_cycles -= 1
if allowed_cycles <= 0:
# Add the remaining models, but do not remove them from the model list
missing_models = [ModelCode(model=m, context=context, stdout=self.stdout, stderr=self.stderr) for m in models]
model_queue += missing_models
# Replace the models with the model class objects
# (sure, this is a little bit of hackery)
models[:] = missing_models
break
else:
allowed_cycles = MAX_CYCLES
return model_queue
def get_lines(self):
""" Returns a list of lists or strings, representing the code body.
Each list is a block, each string is a statement.
"""
code = [self.FILE_HEADER.strip()]
# Queue and process the required models
for model_class in self._queue_models(self.models, context=self.context):
msg = 'Processing model: %s\n' % model_class.model.__name__
self.stderr.write(msg)
code.append(" #" + msg)
code.append(model_class.import_lines)
code.append("")
code.append(model_class.lines)
# Process left over foreign keys from cyclic models
for model in self.models:
msg = 'Re-processing model: %s\n' % model.model.__name__
self.stderr.write(msg)
code.append(" #" + msg)
for instance in model.instances:
if instance.waiting_list or instance.many_to_many_waiting_list:
code.append(instance.get_lines(force=True))
code.insert(1, " #initial imports")
code.insert(2, "")
for key, value in self.context["__extra_imports"].items():
code.insert(2, " from %s import %s" % (value, key))
return code
lines = property(get_lines)
# A user-friendly file header
FILE_HEADER = """
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# This file has been automatically generated.
# Instead of changing it, create a file called import_helper.py
# and put there a class called ImportHelper(object) in it.
#
# This class will be specially casted so that instead of extending object,
# it will actually extend the class BasicImportHelper()
#
# That means you just have to overload the methods you want to
# change, leaving the other ones inteact.
#
# Something that you might want to do is use transactions, for example.
#
# Also, don't forget to add the necessary Django imports.
#
# This file was generated with the following command:
# %s
#
# to restore it, run
# manage.py runscript module_name.this_script_name
#
# example: if manage.py is at ./manage.py
# and the script is at ./some_folder/some_script.py
# you must make sure ./some_folder/__init__.py exists
# and run ./manage.py runscript some_folder.some_script
from django.db import transaction
class BasicImportHelper(object):
def pre_import(self):
pass
# You probably want to uncomment on of these two lines
# @transaction.atomic # Django 1.6
# @transaction.commit_on_success # Django <1.6
def run_import(self, import_data):
import_data()
def post_import(self):
pass
def locate_similar(self, current_object, search_data):
#you will probably want to call this method from save_or_locate()
#example:
#new_obj = self.locate_similar(the_obj, {"national_id": the_obj.national_id } )
the_obj = current_object.__class__.objects.get(**search_data)
return the_obj
def locate_object(self, original_class, original_pk_name, the_class, pk_name, pk_value, obj_content):
#You may change this function to do specific lookup for specific objects
#
#original_class class of the django orm's object that needs to be located
#original_pk_name the primary key of original_class
#the_class parent class of original_class which contains obj_content
#pk_name the primary key of original_class
#pk_value value of the primary_key
#obj_content content of the object which was not exported.
#
#you should use obj_content to locate the object on the target db
#
#and example where original_class and the_class are different is
#when original_class is Farmer and
#the_class is Person. The table may refer to a Farmer but you will actually
#need to locate Person in order to instantiate that Farmer
#
#example:
#if the_class == SurveyResultFormat or the_class == SurveyType or the_class == SurveyState:
# pk_name="name"
# pk_value=obj_content[pk_name]
#if the_class == StaffGroup:
# pk_value=8
search_data = { pk_name: pk_value }
the_obj = the_class.objects.get(**search_data)
#print(the_obj)
return the_obj
def save_or_locate(self, the_obj):
#change this if you want to locate the object in the database
try:
the_obj.save()
except:
print("---------------")
print("Error saving the following object:")
print(the_obj.__class__)
print(" ")
print(the_obj.__dict__)
print(" ")
print(the_obj)
print(" ")
print("---------------")
raise
return the_obj
importer = None
try:
import import_helper
#we need this so ImportHelper can extend BasicImportHelper, although import_helper.py
#has no knowlodge of this class
importer = type("DynamicImportHelper", (import_helper.ImportHelper, BasicImportHelper ) , {} )()
except ImportError as e:
if str(e) == "No module named import_helper":
importer = BasicImportHelper()
else:
raise
import datetime
from decimal import Decimal
from django.contrib.contenttypes.models import ContentType
def run():
importer.pre_import()
importer.run_import(import_data)
importer.post_import()
def import_data():
""" % " ".join(sys.argv)
# HELPER FUNCTIONS
#-------------------------------------------------------------------------------
def flatten_blocks(lines, num_indents=-1):
""" Takes a list (block) or string (statement) and flattens it into a string
with indentation.
"""
# The standard indent is four spaces
INDENTATION = " " * 4
if not lines:
return ""
# If this is a string, add the indentation and finish here
if isinstance(lines, six.string_types):
return INDENTATION * num_indents + lines
# If this is not a string, join the lines and recurse
return "\n".join([flatten_blocks(line, num_indents + 1) for line in lines])
def get_attribute_value(item, field, context, force=False):
""" Gets a string version of the given attribute's value, like repr() might. """
# Find the value of the field, catching any database issues
try:
value = getattr(item, field.name)
except ObjectDoesNotExist:
raise SkipValue('Could not find object for %s.%s, ignoring.\n' % (item.__class__.__name__, field.name))
# AutoField: We don't include the auto fields, they'll be automatically recreated
if isinstance(field, AutoField):
raise SkipValue()
# Some databases (eg MySQL) might store boolean values as 0/1, this needs to be cast as a bool
elif isinstance(field, BooleanField) and value is not None:
return repr(bool(value))
# Post file-storage-refactor, repr() on File/ImageFields no longer returns the path
elif isinstance(field, FileField):
return repr(force_unicode(value))
# ForeignKey fields, link directly using our stored python variable name
elif isinstance(field, ForeignKey) and value is not None:
# Special case for contenttype foreign keys: no need to output any
# content types in this script, as they can be generated again
# automatically.
# NB: Not sure if "is" will always work
if field.rel.to is ContentType:
return 'ContentType.objects.get(app_label="%s", model="%s")' % (value.app_label, value.model)
# Generate an identifier (key) for this foreign object
pk_name = value._meta.pk.name
key = '%s_%s' % (value.__class__.__name__, getattr(value, pk_name))
if key in context:
variable_name = context[key]
# If the context value is set to None, this should be skipped.
# This identifies models that have been skipped (inheritance)
if variable_name is None:
raise SkipValue()
# Return the variable name listed in the context
return "%s" % variable_name
elif value.__class__ not in context["__avaliable_models"] or force:
context["__extra_imports"][value._meta.object_name] = value.__module__
item_locator = orm_item_locator(value)
return item_locator
else:
raise DoLater('(FK) %s.%s\n' % (item.__class__.__name__, field.name))
# A normal field (e.g. a python built-in)
else:
return repr(value)
def make_clean_dict(the_dict):
if "_state" in the_dict:
clean_dict = the_dict.copy()
del clean_dict["_state"]
return clean_dict
return the_dict
def check_dependencies(model, model_queue, avaliable_models):
" Check that all the depenedencies for this model are already in the queue. "
# A list of allowed links: existing fields, itself and the special case ContentType
allowed_links = [m.model.__name__ for m in model_queue] + [model.__name__, 'ContentType']
# For each ForeignKey or ManyToMany field, check that a link is possible
for field in model._meta.fields:
if field.rel and field.rel.to.__name__ not in allowed_links:
if field.rel.to not in avaliable_models:
continue
return False
for field in model._meta.many_to_many:
if field.rel and field.rel.to.__name__ not in allowed_links:
return False
return True
# EXCEPTIONS
#-------------------------------------------------------------------------------
class SkipValue(Exception):
""" Value could not be parsed or should simply be skipped. """
class DoLater(Exception):
""" Value could not be parsed or should simply be skipped. """