Source

south with list of databases under migration support / south / modelsinspector.py

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
"""
Like the old south.modelsparser, but using introspection where possible
rather than direct inspection of models.py.
"""

import datetime
import re
import decimal

from south.utils import get_attribute, auto_through

from django.db import models
from django.db.models.base import ModelBase, Model
from django.db.models.fields import NOT_PROVIDED
from django.conf import settings
from django.utils.functional import Promise
from django.contrib.contenttypes import generic
from django.utils.datastructures import SortedDict
from django.utils import datetime_safe

NOISY = False

# Gives information about how to introspect certain fields.
# This is a list of triples; the first item is a list of fields it applies to,
# (note that isinstance is used, so superclasses are perfectly valid here)
# the second is a list of positional argument descriptors, and the third
# is a list of keyword argument descriptors.
# Descriptors are of the form:
#  [attrname, options]
# Where attrname is the attribute on the field to get the value from, and options
# is an optional dict.
#
# The introspector uses the combination of all matching entries, in order.
introspection_details = [
    (
        (models.Field, ),
        [],
        {
            "null": ["null", {"default": False}],
            "blank": ["blank", {"default": False, "ignore_if":"primary_key"}],
            "primary_key": ["primary_key", {"default": False}],
            "max_length": ["max_length", {"default": None}],
            "unique": ["_unique", {"default": False}],
            "db_index": ["db_index", {"default": False}],
            "default": ["default", {"default": NOT_PROVIDED, "ignore_dynamics": True}],
            "db_column": ["db_column", {"default": None}],
            "db_tablespace": ["db_tablespace", {"default": settings.DEFAULT_INDEX_TABLESPACE}],
        },
    ),
    (
        (models.ForeignKey, models.OneToOneField),
        [],
        {
            "to": ["rel.to", {}],
            "to_field": ["rel.field_name", {"default_attr": "rel.to._meta.pk.name"}],
            "related_name": ["rel.related_name", {"default": None}],
            "db_index": ["db_index", {"default": True}],
        },
    ),
    (
        (models.ManyToManyField,),
        [],
        {
            "to": ["rel.to", {}],
            "symmetrical": ["rel.symmetrical", {"default": True}],
            "related_name": ["rel.related_name", {"default": None}],
            "db_table": ["db_table", {"default": None}],
            # TODO: Kind of ugly to add this one-time-only option
            "through": ["rel.through", {"ignore_if_auto_through": True}],
        },
    ),
    (
        (models.DateField, models.TimeField),
        [],
        {
            "auto_now": ["auto_now", {"default": False}],
            "auto_now_add": ["auto_now_add", {"default": False}],
        },
    ),
    (
        (models.DecimalField, ),
        [],
        {
            "max_digits": ["max_digits", {"default": None}],
            "decimal_places": ["decimal_places", {"default": None}],
        },
    ),
    (
        (models.SlugField, ),
        [],
        {
            "db_index": ["db_index", {"default": True}],
        },
    ),
    (
        (models.BooleanField, ),
        [],
        {
            "default": ["default", {"default": NOT_PROVIDED, "converter": bool}],
            "blank": ["blank", {"default": True, "ignore_if":"primary_key"}],
        },
    ),
    (
        (models.FilePathField, ),
        [],
        {
            "path": ["path", {"default": ''}],
            "match": ["match", {"default": None}],
            "recursive": ["recursive", {"default": False}],
        },
    ),
    (
        (generic.GenericRelation, ),
        [],
        {
            "to": ["rel.to", {}],
            "symmetrical": ["rel.symmetrical", {"default": True}],
            "object_id_field": ["object_id_field_name", {"default": "object_id"}],
            "content_type_field": ["content_type_field_name", {"default": "content_type"}],
            "blank": ["blank", {"default": True}],
        },
    ),
]

# Regexes of allowed field full paths
allowed_fields = [
    "^django\.db",
    "^django\.contrib\.contenttypes\.generic",
    "^django\.contrib\.localflavor",
]

# Regexes of ignored fields (custom fields which look like fields, but have no column behind them)
ignored_fields = [
    "^django\.contrib\.contenttypes\.generic\.GenericRelation",
    "^django\.contrib\.contenttypes\.generic\.GenericForeignKey",
]

# Similar, but for Meta, so just the inner level (kwds).
meta_details = {
    "db_table": ["db_table", {"default_attr_concat": ["%s_%s", "app_label", "module_name"]}],
    "db_tablespace": ["db_tablespace", {"default": settings.DEFAULT_TABLESPACE}],
    "unique_together": ["unique_together", {"default": []}],
    "ordering": ["ordering", {"default": []}],
    "proxy": ["proxy", {"default": False, "ignore_missing": True}],
}

# 2.4 compatability
any = lambda x: reduce(lambda y, z: y or z, x, False)


def add_introspection_rules(rules=[], patterns=[]):
    "Allows you to add some introspection rules at runtime, e.g. for 3rd party apps."
    assert isinstance(rules, (list, tuple))
    assert isinstance(patterns, (list, tuple))
    allowed_fields.extend(patterns)
    introspection_details.extend(rules)

def add_ignored_fields(patterns):
    "Allows you to add some ignore field patterns."
    assert isinstance(patterns, (list, tuple))
    ignored_fields.extend(patterns)
    
def can_ignore(field):
    """
    Returns True if we know for certain that we can ignore this field, False
    otherwise.
    """
    full_name = "%s.%s" % (field.__class__.__module__, field.__class__.__name__)
    for regex in ignored_fields:
        if re.match(regex, full_name):
            return True
    return False

def can_introspect(field):
    """
    Returns True if we are allowed to introspect this field, False otherwise.
    ('allowed' means 'in core'. Custom fields can declare they are introspectable
    by the default South rules by adding the attribute _south_introspects = True.)
    """
    # Check for special attribute
    if hasattr(field, "_south_introspects") and field._south_introspects:
        return True
    # Check it's an introspectable field
    full_name = "%s.%s" % (field.__class__.__module__, field.__class__.__name__)
    for regex in allowed_fields:
        if re.match(regex, full_name):
            return True
    return False


def matching_details(field):
    """
    Returns the union of all matching entries in introspection_details for the field.
    """
    our_args = []
    our_kwargs = {}
    for classes, args, kwargs in introspection_details:
        if any([isinstance(field, x) for x in classes]):
            our_args.extend(args)
            our_kwargs.update(kwargs)
    return our_args, our_kwargs


class IsDefault(Exception):
    """
    Exception for when a field contains its default value.
    """


def get_value(field, descriptor):
    """
    Gets an attribute value from a Field instance and formats it.
    """
    attrname, options = descriptor
    # If the options say it's not a attribute name but a real value, use that.
    if options.get('is_value', False):
        value = attrname
    else:
        try:
            value = get_attribute(field, attrname)
        except AttributeError:
            if options.get("ignore_missing", False):
                raise IsDefault
            else:
                raise
    # Lazy-eval functions get eval'd.
    if isinstance(value, Promise):
        value = unicode(value)
    # If the value is the same as the default, omit it for clarity
    if "default" in options and value == options['default']:
        raise IsDefault
    # If there's an ignore_if, use it
    if "ignore_if" in options:
        if get_attribute(field, options['ignore_if']):
            raise IsDefault
    # If there's an ignore_if_auto_through which is True, use it
    if options.get("ignore_if_auto_through", False):
        if auto_through(field):
            raise IsDefault
    # Some default values need to be gotten from an attribute too.
    if "default_attr" in options:
        default_value = get_attribute(field, options['default_attr'])
        if value == default_value:
            raise IsDefault
    # Some are made from a formatting string and several attrs (e.g. db_table)
    if "default_attr_concat" in options:
        format, attrs = options['default_attr_concat'][0], options['default_attr_concat'][1:]
        default_value = format % tuple(map(lambda x: get_attribute(field, x), attrs))
        if value == default_value:
            raise IsDefault
    # Callables get called.
    if callable(value) and not isinstance(value, ModelBase):
        # Datetime.datetime.now is special, as we can access it from the eval
        # context (and because it changes all the time; people will file bugs otherwise).
        if value == datetime.datetime.now:
            return "datetime.datetime.now"
        if value == datetime.datetime.utcnow:
            return "datetime.datetime.utcnow"
        if value == datetime.date.today:
            return "datetime.date.today"
        # All other callables get called.
        value = value()
    # Models get their own special repr()
    if isinstance(value, ModelBase):
        # If it's a proxy model, follow it back to its non-proxy parent
        if getattr(value._meta, "proxy", False):
            value = value._meta.proxy_for_model
        return "orm['%s.%s']" % (value._meta.app_label, value._meta.object_name)
    # As do model instances
    if isinstance(value, Model):
        if options.get("ignore_dynamics", False):
            raise IsDefault
        return "orm['%s.%s'].objects.get(pk=%r)" % (value.__class__._meta.app_label, value.__class__._meta.object_name, value.pk)
    # Make sure Decimal is converted down into a string
    if isinstance(value, decimal.Decimal):
        value = str(value)
    if isinstance(value, (datetime.datetime, datetime.time)):
        value = dumb_down_timezone(value)
    # datetime_safe has an improper repr value
    if isinstance(value, datetime_safe.datetime):
        value = datetime.datetime(*value.utctimetuple()[:7])
    if isinstance(value, datetime_safe.date):
        value = datetime.date(*value.timetuple()[:3])
    # Now, apply the converter func if there is one
    if "converter" in options:
        value = options['converter'](value)
    # Return the final value
    return repr(value)

def dumb_down_timezone(value):
    try:
        from django.utils import timezone
    except ImportError:
        pass
    else:
        if settings.USE_TZ and timezone.is_aware(value):
            value = value.astimezone(timezone.utc).replace(tzinfo=None)
    return value


def introspector(field):
    """
    Given a field, introspects its definition triple.
    """
    arg_defs, kwarg_defs = matching_details(field)
    args = []
    kwargs = {}
    # For each argument, use the descriptor to get the real value.
    for defn in arg_defs:
        try:
            args.append(get_value(field, defn))
        except IsDefault:
            pass
    for kwd, defn in kwarg_defs.items():
        try:
            kwargs[kwd] = get_value(field, defn)
        except IsDefault:
            pass
    return args, kwargs


def get_model_fields(model, m2m=False):
    """
    Given a model class, returns a dict of {field_name: field_triple} defs.
    """
    
    field_defs = SortedDict()
    inherited_fields = {}
    
    # Go through all bases (that are themselves models, but not Model)
    for base in model.__bases__:
        if hasattr(base, '_meta') and issubclass(base, models.Model):
            if not base._meta.abstract:
                # Looks like we need their fields, Ma.
                inherited_fields.update(get_model_fields(base))
    
    # Now, go through all the fields and try to get their definition
    source = model._meta.local_fields[:]
    if m2m:
        source += model._meta.local_many_to_many
    
    for field in source:
        # Can we ignore it completely?
        if can_ignore(field):
            continue
        # Does it define a south_field_triple method?
        if hasattr(field, "south_field_triple"):
            if NOISY:
                print " ( Nativing field: %s" % field.name
            field_defs[field.name] = field.south_field_triple()
        # Can we introspect it?
        elif can_introspect(field):
            # Get the full field class path.
            field_class = field.__class__.__module__ + "." + field.__class__.__name__
            # Run this field through the introspector
            args, kwargs = introspector(field)
            # Workaround for Django bug #13987
            if model._meta.pk.column == field.column and 'primary_key' not in kwargs:
                kwargs['primary_key'] = True
            # That's our definition!
            field_defs[field.name] = (field_class, args, kwargs)
        # Shucks, no definition!
        else:
            if NOISY:
                print " ( Nodefing field: %s" % field.name
            field_defs[field.name] = None
    
    # If they've used the horrific hack that is order_with_respect_to, deal with
    # it.
    if model._meta.order_with_respect_to:
        field_defs['_order'] = ("django.db.models.fields.IntegerField", [], {"default": "0"})
    
    return field_defs


def get_model_meta(model):
    """
    Given a model class, will return the dict representing the Meta class.
    """
    
    # Get the introspected attributes
    meta_def = {}
    for kwd, defn in meta_details.items():
        try:
            meta_def[kwd] = get_value(model._meta, defn)
        except IsDefault:
            pass
    
    # Also, add on any non-abstract model base classes.
    # This is called _ormbases as the _bases variable was previously used
    # for a list of full class paths to bases, so we can't conflict.
    for base in model.__bases__:
        if hasattr(base, '_meta') and issubclass(base, models.Model):
            if not base._meta.abstract:
                # OK, that matches our terms.
                if "_ormbases" not in meta_def:
                    meta_def['_ormbases'] = []
                meta_def['_ormbases'].append("%s.%s" % (
                    base._meta.app_label,
                    base._meta.object_name,
                ))
    
    return meta_def


# Now, load the built-in South introspection plugins
import south.introspection_plugins