| """ |
| Extensions to Django's model logic. |
| """ |
| |
| import re |
| import django.core.exceptions |
| from django.db import models as dbmodels, backend, connection |
| from django.db.models.sql import query |
| from django.utils import datastructures |
| from autotest_lib.frontend.afe import readonly_connection |
| |
| |
| class ValidationError(Exception): |
| """\ |
| Data validation error in adding or updating an object. The associated |
| value is a dictionary mapping field names to error strings. |
| """ |
| |
| |
| def _wrap_with_readonly(method): |
| def wrapper_method(*args, **kwargs): |
| readonly_connection.connection().set_django_connection() |
| try: |
| return method(*args, **kwargs) |
| finally: |
| readonly_connection.connection().unset_django_connection() |
| wrapper_method.__name__ = method.__name__ |
| return wrapper_method |
| |
| |
| def _quote_name(name): |
| """Shorthand for connection.ops.quote_name().""" |
| return connection.ops.quote_name(name) |
| |
| |
| def _wrap_generator_with_readonly(generator): |
| """ |
| We have to wrap generators specially. Assume it performs |
| the query on the first call to next(). |
| """ |
| def wrapper_generator(*args, **kwargs): |
| generator_obj = generator(*args, **kwargs) |
| readonly_connection.connection().set_django_connection() |
| try: |
| first_value = generator_obj.next() |
| finally: |
| readonly_connection.connection().unset_django_connection() |
| yield first_value |
| |
| while True: |
| yield generator_obj.next() |
| |
| wrapper_generator.__name__ = generator.__name__ |
| return wrapper_generator |
| |
| |
| def _make_queryset_readonly(queryset): |
| """ |
| Wrap all methods that do database queries with a readonly connection. |
| """ |
| db_query_methods = ['count', 'get', 'get_or_create', 'latest', 'in_bulk', |
| 'delete'] |
| for method_name in db_query_methods: |
| method = getattr(queryset, method_name) |
| wrapped_method = _wrap_with_readonly(method) |
| setattr(queryset, method_name, wrapped_method) |
| |
| queryset.iterator = _wrap_generator_with_readonly(queryset.iterator) |
| |
| |
| class ReadonlyQuerySet(dbmodels.query.QuerySet): |
| """ |
| QuerySet object that performs all database queries with the read-only |
| connection. |
| """ |
| def __init__(self, model=None, *args, **kwargs): |
| super(ReadonlyQuerySet, self).__init__(model, *args, **kwargs) |
| _make_queryset_readonly(self) |
| |
| |
| def values(self, *fields): |
| return self._clone(klass=ReadonlyValuesQuerySet, |
| setup=True, _fields=fields) |
| |
| |
| class ReadonlyValuesQuerySet(dbmodels.query.ValuesQuerySet): |
| def __init__(self, model=None, *args, **kwargs): |
| super(ReadonlyValuesQuerySet, self).__init__(model, *args, **kwargs) |
| _make_queryset_readonly(self) |
| |
| |
| class ExtendedManager(dbmodels.Manager): |
| """\ |
| Extended manager supporting subquery filtering. |
| """ |
| |
| class _CustomQuery(query.Query): |
| def clone(self, klass=None, **kwargs): |
| obj = super(ExtendedManager._CustomQuery, self).clone( |
| klass, _customSqlQ=self._customSqlQ) |
| |
| customQ = kwargs.get('_customSqlQ', None) |
| if customQ is not None: |
| obj._customSqlQ._joins.update(customQ._joins) |
| obj._customSqlQ._where.extend(customQ._where) |
| obj._customSqlQ._params.extend(customQ._params) |
| |
| return obj |
| |
| def get_from_clause(self): |
| from_, params = super( |
| ExtendedManager._CustomQuery, self).get_from_clause() |
| |
| join_clause = '' |
| for join_alias, join in self._customSqlQ._joins.iteritems(): |
| join_table, join_type, condition = join |
| join_clause += ' %s %s AS %s ON (%s)' % ( |
| join_type, join_table, join_alias, condition) |
| |
| if join_clause: |
| from_.append(join_clause) |
| |
| return from_, params |
| |
| |
| class _CustomSqlQ(dbmodels.Q): |
| def __init__(self): |
| self._joins = datastructures.SortedDict() |
| self._where, self._params = [], [] |
| |
| |
| def add_join(self, table, condition, join_type, alias=None): |
| if alias is None: |
| alias = table |
| self._joins[alias] = (table, join_type, condition) |
| |
| |
| def add_where(self, where, params=[]): |
| self._where.append(where) |
| self._params.extend(params) |
| |
| |
| def add_to_query(self, query, aliases): |
| if self._where: |
| where = ' AND '.join(self._where) |
| query.add_extra(None, None, (where,), self._params, None, None) |
| |
| |
| def _add_customSqlQ(self, query_set, filter_object): |
| """\ |
| Add a _CustomSqlQ to the query set. |
| """ |
| # Make a copy of the query set |
| query_set = query_set.all() |
| |
| query_set.query = query_set.query.clone( |
| ExtendedManager._CustomQuery, _customSqlQ=filter_object) |
| return query_set.filter(filter_object) |
| |
| |
| def add_join(self, query_set, join_table, join_key, |
| join_condition='', suffix='', exclude=False, |
| force_left_join=False): |
| """ |
| Add a join to query_set. |
| @param join_table table to join to |
| @param join_key field referencing back to this model to use for the join |
| @param join_condition extra condition for the ON clause of the join |
| @param suffix suffix to add to join_table for the join alias |
| @param exclude if true, exclude rows that match this join (will use a |
| LEFT OUTER JOIN and an appropriate WHERE condition) |
| @param force_left_join - if true, a LEFT OUTER JOIN will be used |
| instead of an INNER JOIN regardless of other options |
| """ |
| join_from_table = self.model._meta.db_table |
| join_from_key = self.model._meta.pk.name |
| join_alias = join_table + suffix |
| full_join_key = join_alias + '.' + join_key |
| full_join_condition = '%s = %s.%s' % (full_join_key, join_from_table, |
| join_from_key) |
| if join_condition: |
| full_join_condition += ' AND (' + join_condition + ')' |
| if exclude or force_left_join: |
| join_type = query_set.query.LOUTER |
| else: |
| join_type = query_set.query.INNER |
| |
| filter_object = self._CustomSqlQ() |
| filter_object.add_join(join_table, |
| full_join_condition, |
| join_type, |
| alias=join_alias) |
| if exclude: |
| filter_object.add_where(full_join_key + ' IS NULL') |
| |
| query_set = self._add_customSqlQ(query_set, filter_object) |
| return query_set |
| |
| |
| def _get_quoted_field(self, table, field): |
| return _quote_name(table) + '.' + _quote_name(field) |
| |
| |
| def get_key_on_this_table(self, key_field=None): |
| if key_field is None: |
| # default to primary key |
| key_field = self.model._meta.pk.column |
| return self._get_quoted_field(self.model._meta.db_table, key_field) |
| |
| |
| def escape_user_sql(self, sql): |
| return sql.replace('%', '%%') |
| |
| |
| def _custom_select_query(self, query_set, selects): |
| sql, params = query_set.query.as_sql() |
| from_ = sql[sql.find(' FROM'):] |
| |
| if query_set.query.distinct: |
| distinct = 'DISTINCT ' |
| else: |
| distinct = '' |
| |
| sql_query = ('SELECT ' + distinct + ','.join(selects) + from_) |
| cursor = readonly_connection.connection().cursor() |
| cursor.execute(sql_query, params) |
| return cursor.fetchall() |
| |
| |
| def _is_relation_to(self, field, model_class): |
| return field.rel and field.rel.to is model_class |
| |
| |
| def _get_pivot_iterator(self, base_objects_by_id, related_model): |
| """ |
| Determine the relationship between this model and related_model, and |
| return a pivot iterator. |
| @param base_objects_by_id: dict of instances of this model indexed by |
| their IDs |
| @returns a pivot iterator, which yields a tuple (base_object, |
| related_object) for each relationship between a base object and a |
| related object. all base_object instances come from base_objects_by_id. |
| Note -- this depends on Django model internals and will likely need to |
| be updated when we move to Django 1.x. |
| """ |
| # look for a field on related_model relating to this model |
| for field in related_model._meta.fields: |
| if self._is_relation_to(field, self.model): |
| # many-to-one |
| return self._many_to_one_pivot(base_objects_by_id, |
| related_model, field) |
| |
| for field in related_model._meta.many_to_many: |
| if self._is_relation_to(field, self.model): |
| # many-to-many |
| return self._many_to_many_pivot( |
| base_objects_by_id, related_model, field.m2m_db_table(), |
| field.m2m_reverse_name(), field.m2m_column_name()) |
| |
| # maybe this model has the many-to-many field |
| for field in self.model._meta.many_to_many: |
| if self._is_relation_to(field, related_model): |
| return self._many_to_many_pivot( |
| base_objects_by_id, related_model, field.m2m_db_table(), |
| field.m2m_column_name(), field.m2m_reverse_name()) |
| |
| raise ValueError('%s has no relation to %s' % |
| (related_model, self.model)) |
| |
| |
| def _many_to_one_pivot(self, base_objects_by_id, related_model, |
| foreign_key_field): |
| """ |
| @returns a pivot iterator - see _get_pivot_iterator() |
| """ |
| filter_data = {foreign_key_field.name + '__pk__in': |
| base_objects_by_id.keys()} |
| for related_object in related_model.objects.filter(**filter_data): |
| # lookup base object in the dict, rather than grabbing it from the |
| # related object. we need to return instances from the dict, not |
| # fresh instances of the same models (and grabbing model instances |
| # from the related models incurs a DB query each time). |
| base_object_id = getattr(related_object, foreign_key_field.attname) |
| base_object = base_objects_by_id[base_object_id] |
| yield base_object, related_object |
| |
| |
| def _query_pivot_table(self, base_objects_by_id, pivot_table, |
| pivot_from_field, pivot_to_field): |
| """ |
| @param id_list list of IDs of self.model objects to include |
| @param pivot_table the name of the pivot table |
| @param pivot_from_field a field name on pivot_table referencing |
| self.model |
| @param pivot_to_field a field name on pivot_table referencing the |
| related model. |
| @returns pivot list of IDs (base_id, related_id) |
| """ |
| query = """ |
| SELECT %(from_field)s, %(to_field)s |
| FROM %(table)s |
| WHERE %(from_field)s IN (%(id_list)s) |
| """ % dict(from_field=pivot_from_field, |
| to_field=pivot_to_field, |
| table=pivot_table, |
| id_list=','.join(str(id_) for id_ |
| in base_objects_by_id.iterkeys())) |
| cursor = readonly_connection.connection().cursor() |
| cursor.execute(query) |
| return cursor.fetchall() |
| |
| |
| def _many_to_many_pivot(self, base_objects_by_id, related_model, |
| pivot_table, pivot_from_field, pivot_to_field): |
| """ |
| @param pivot_table: see _query_pivot_table |
| @param pivot_from_field: see _query_pivot_table |
| @param pivot_to_field: see _query_pivot_table |
| @returns a pivot iterator - see _get_pivot_iterator() |
| """ |
| id_pivot = self._query_pivot_table(base_objects_by_id, pivot_table, |
| pivot_from_field, pivot_to_field) |
| |
| all_related_ids = list(set(related_id for base_id, related_id |
| in id_pivot)) |
| related_objects_by_id = related_model.objects.in_bulk(all_related_ids) |
| |
| for base_id, related_id in id_pivot: |
| yield base_objects_by_id[base_id], related_objects_by_id[related_id] |
| |
| |
| def populate_relationships(self, base_objects, related_model, |
| related_list_name): |
| """ |
| For each instance of this model in base_objects, add a field named |
| related_list_name listing all the related objects of type related_model. |
| related_model must be in a many-to-one or many-to-many relationship with |
| this model. |
| @param base_objects - list of instances of this model |
| @param related_model - model class related to this model |
| @param related_list_name - attribute name in which to store the related |
| object list. |
| """ |
| if not base_objects: |
| # if we don't bail early, we'll get a SQL error later |
| return |
| |
| base_objects_by_id = dict((base_object._get_pk_val(), base_object) |
| for base_object in base_objects) |
| pivot_iterator = self._get_pivot_iterator(base_objects_by_id, |
| related_model) |
| |
| for base_object in base_objects: |
| setattr(base_object, related_list_name, []) |
| |
| for base_object, related_object in pivot_iterator: |
| getattr(base_object, related_list_name).append(related_object) |
| |
| |
| class ValidObjectsManager(ExtendedManager): |
| """ |
| Manager returning only objects with invalid=False. |
| """ |
| def get_query_set(self): |
| queryset = super(ValidObjectsManager, self).get_query_set() |
| return queryset.filter(invalid=False) |
| |
| |
| class ModelExtensions(object): |
| """\ |
| Mixin with convenience functions for models, built on top of the |
| default Django model functions. |
| """ |
| # TODO: at least some of these functions really belong in a custom |
| # Manager class |
| |
| field_dict = None |
| # subclasses should override if they want to support smart_get() by name |
| name_field = None |
| |
| |
| @classmethod |
| def get_field_dict(cls): |
| if cls.field_dict is None: |
| cls.field_dict = {} |
| for field in cls._meta.fields: |
| cls.field_dict[field.name] = field |
| return cls.field_dict |
| |
| |
| @classmethod |
| def clean_foreign_keys(cls, data): |
| """\ |
| -Convert foreign key fields in data from <field>_id to just |
| <field>. |
| -replace foreign key objects with their IDs |
| This method modifies data in-place. |
| """ |
| for field in cls._meta.fields: |
| if not field.rel: |
| continue |
| if (field.attname != field.name and |
| field.attname in data): |
| data[field.name] = data[field.attname] |
| del data[field.attname] |
| if field.name not in data: |
| continue |
| value = data[field.name] |
| if isinstance(value, dbmodels.Model): |
| data[field.name] = value._get_pk_val() |
| |
| |
| @classmethod |
| def _convert_booleans(cls, data): |
| """ |
| Ensure BooleanFields actually get bool values. The Django MySQL |
| backend returns ints for BooleanFields, which is almost always not |
| a problem, but it can be annoying in certain situations. |
| """ |
| for field in cls._meta.fields: |
| if type(field) == dbmodels.BooleanField and field.name in data: |
| data[field.name] = bool(data[field.name]) |
| |
| |
| # TODO(showard) - is there a way to not have to do this? |
| @classmethod |
| def provide_default_values(cls, data): |
| """\ |
| Provide default values for fields with default values which have |
| nothing passed in. |
| |
| For CharField and TextField fields with "blank=True", if nothing |
| is passed, we fill in an empty string value, even if there's no |
| default set. |
| """ |
| new_data = dict(data) |
| field_dict = cls.get_field_dict() |
| for name, obj in field_dict.iteritems(): |
| if data.get(name) is not None: |
| continue |
| if obj.default is not dbmodels.fields.NOT_PROVIDED: |
| new_data[name] = obj.default |
| elif (isinstance(obj, dbmodels.CharField) or |
| isinstance(obj, dbmodels.TextField)): |
| new_data[name] = '' |
| return new_data |
| |
| |
| @classmethod |
| def convert_human_readable_values(cls, data, to_human_readable=False): |
| """\ |
| Performs conversions on user-supplied field data, to make it |
| easier for users to pass human-readable data. |
| |
| For all fields that have choice sets, convert their values |
| from human-readable strings to enum values, if necessary. This |
| allows users to pass strings instead of the corresponding |
| integer values. |
| |
| For all foreign key fields, call smart_get with the supplied |
| data. This allows the user to pass either an ID value or |
| the name of the object as a string. |
| |
| If to_human_readable=True, perform the inverse - i.e. convert |
| numeric values to human readable values. |
| |
| This method modifies data in-place. |
| """ |
| field_dict = cls.get_field_dict() |
| for field_name in data: |
| if field_name not in field_dict or data[field_name] is None: |
| continue |
| field_obj = field_dict[field_name] |
| # convert enum values |
| if field_obj.choices: |
| for choice_data in field_obj.choices: |
| # choice_data is (value, name) |
| if to_human_readable: |
| from_val, to_val = choice_data |
| else: |
| to_val, from_val = choice_data |
| if from_val == data[field_name]: |
| data[field_name] = to_val |
| break |
| # convert foreign key values |
| elif field_obj.rel: |
| dest_obj = field_obj.rel.to.smart_get(data[field_name], |
| valid_only=False) |
| if to_human_readable: |
| if dest_obj.name_field is not None: |
| data[field_name] = getattr(dest_obj, |
| dest_obj.name_field) |
| else: |
| data[field_name] = dest_obj |
| |
| |
| @classmethod |
| def validate_field_names(cls, data): |
| 'Checks for extraneous fields in data.' |
| errors = {} |
| field_dict = cls.get_field_dict() |
| for field_name in data: |
| if field_name not in field_dict: |
| errors[field_name] = 'No field of this name' |
| return errors |
| |
| |
| @classmethod |
| def prepare_data_args(cls, data, kwargs): |
| 'Common preparation for add_object and update_object' |
| data = dict(data) # don't modify the default keyword arg |
| data.update(kwargs) |
| # must check for extraneous field names here, while we have the |
| # data in a dict |
| errors = cls.validate_field_names(data) |
| if errors: |
| raise ValidationError(errors) |
| cls.convert_human_readable_values(data) |
| return data |
| |
| |
| def validate_unique(self): |
| """\ |
| Validate that unique fields are unique. Django manipulators do |
| this too, but they're a huge pain to use manually. Trust me. |
| """ |
| errors = {} |
| cls = type(self) |
| field_dict = self.get_field_dict() |
| manager = cls.get_valid_manager() |
| for field_name, field_obj in field_dict.iteritems(): |
| if not field_obj.unique: |
| continue |
| |
| value = getattr(self, field_name) |
| if value is None and field_obj.auto_created: |
| # don't bother checking autoincrement fields about to be |
| # generated |
| continue |
| |
| existing_objs = manager.filter(**{field_name : value}) |
| num_existing = existing_objs.count() |
| |
| if num_existing == 0: |
| continue |
| if num_existing == 1 and existing_objs[0].id == self.id: |
| continue |
| errors[field_name] = ( |
| 'This value must be unique (%s)' % (value)) |
| return errors |
| |
| |
| def _validate(self): |
| """ |
| First coerces all fields on this instance to their proper Python types. |
| Then runs validation on every field. Returns a dictionary of |
| field_name -> error_list. |
| |
| Based on validate() from django.db.models.Model in Django 0.96, which |
| was removed in Django 1.0. It should reappear in a later version. See: |
| http://code.djangoproject.com/ticket/6845 |
| """ |
| error_dict = {} |
| for f in self._meta.fields: |
| try: |
| python_value = f.to_python( |
| getattr(self, f.attname, f.get_default())) |
| except django.core.exceptions.ValidationError, e: |
| error_dict[f.name] = str(e.message) |
| continue |
| |
| if not f.blank and not python_value: |
| error_dict[f.name] = 'This field is required.' |
| continue |
| |
| setattr(self, f.attname, python_value) |
| |
| return error_dict |
| |
| |
| def do_validate(self): |
| errors = self._validate() |
| unique_errors = self.validate_unique() |
| for field_name, error in unique_errors.iteritems(): |
| errors.setdefault(field_name, error) |
| if errors: |
| raise ValidationError(errors) |
| |
| |
| # actually (externally) useful methods follow |
| |
| @classmethod |
| def add_object(cls, data={}, **kwargs): |
| """\ |
| Returns a new object created with the given data (a dictionary |
| mapping field names to values). Merges any extra keyword args |
| into data. |
| """ |
| data = cls.prepare_data_args(data, kwargs) |
| data = cls.provide_default_values(data) |
| obj = cls(**data) |
| obj.do_validate() |
| obj.save() |
| return obj |
| |
| |
| def update_object(self, data={}, **kwargs): |
| """\ |
| Updates the object with the given data (a dictionary mapping |
| field names to values). Merges any extra keyword args into |
| data. |
| """ |
| data = self.prepare_data_args(data, kwargs) |
| for field_name, value in data.iteritems(): |
| setattr(self, field_name, value) |
| self.do_validate() |
| self.save() |
| |
| |
| # see query_objects() |
| _SPECIAL_FILTER_KEYS = ('query_start', 'query_limit', 'sort_by', |
| 'extra_args', 'extra_where', 'no_distinct') |
| |
| |
| @classmethod |
| def _extract_special_params(cls, filter_data): |
| """ |
| @returns a tuple of dicts (special_params, regular_filters), where |
| special_params contains the parameters we handle specially and |
| regular_filters is the remaining data to be handled by Django. |
| """ |
| regular_filters = dict(filter_data) |
| special_params = {} |
| for key in cls._SPECIAL_FILTER_KEYS: |
| if key in regular_filters: |
| special_params[key] = regular_filters.pop(key) |
| return special_params, regular_filters |
| |
| |
| @classmethod |
| def apply_presentation(cls, query, filter_data): |
| """ |
| Apply presentation parameters -- sorting and paging -- to the given |
| query. |
| @returns new query with presentation applied |
| """ |
| special_params, _ = cls._extract_special_params(filter_data) |
| sort_by = special_params.get('sort_by', None) |
| if sort_by: |
| assert isinstance(sort_by, list) or isinstance(sort_by, tuple) |
| query = query.order_by(*sort_by) |
| |
| query_start = special_params.get('query_start', None) |
| query_limit = special_params.get('query_limit', None) |
| if query_start is not None: |
| if query_limit is None: |
| raise ValueError('Cannot pass query_start without query_limit') |
| # query_limit is passed as a page size |
| query_limit += query_start |
| return query[query_start:query_limit] |
| |
| |
| @classmethod |
| def query_objects(cls, filter_data, valid_only=True, initial_query=None, |
| apply_presentation=True): |
| """\ |
| Returns a QuerySet object for querying the given model_class |
| with the given filter_data. Optional special arguments in |
| filter_data include: |
| -query_start: index of first return to return |
| -query_limit: maximum number of results to return |
| -sort_by: list of fields to sort on. prefixing a '-' onto a |
| field name changes the sort to descending order. |
| -extra_args: keyword args to pass to query.extra() (see Django |
| DB layer documentation) |
| -extra_where: extra WHERE clause to append |
| -no_distinct: if True, a DISTINCT will not be added to the SELECT |
| """ |
| special_params, regular_filters = cls._extract_special_params( |
| filter_data) |
| |
| if initial_query is None: |
| if valid_only: |
| initial_query = cls.get_valid_manager() |
| else: |
| initial_query = cls.objects |
| |
| query = initial_query.filter(**regular_filters) |
| |
| use_distinct = not special_params.get('no_distinct', False) |
| if use_distinct: |
| query = query.distinct() |
| |
| extra_args = special_params.get('extra_args', {}) |
| extra_where = special_params.get('extra_where', None) |
| if extra_where: |
| # escape %'s |
| extra_where = cls.objects.escape_user_sql(extra_where) |
| extra_args.setdefault('where', []).append(extra_where) |
| if extra_args: |
| query = query.extra(**extra_args) |
| query = query._clone(klass=ReadonlyQuerySet) |
| |
| if apply_presentation: |
| query = cls.apply_presentation(query, filter_data) |
| |
| return query |
| |
| |
| @classmethod |
| def query_count(cls, filter_data, initial_query=None): |
| """\ |
| Like query_objects, but retreive only the count of results. |
| """ |
| filter_data.pop('query_start', None) |
| filter_data.pop('query_limit', None) |
| query = cls.query_objects(filter_data, initial_query=initial_query) |
| return query.count() |
| |
| |
| @classmethod |
| def clean_object_dicts(cls, field_dicts): |
| """\ |
| Take a list of dicts corresponding to object (as returned by |
| query.values()) and clean the data to be more suitable for |
| returning to the user. |
| """ |
| for field_dict in field_dicts: |
| cls.clean_foreign_keys(field_dict) |
| cls._convert_booleans(field_dict) |
| cls.convert_human_readable_values(field_dict, |
| to_human_readable=True) |
| |
| |
| @classmethod |
| def list_objects(cls, filter_data, initial_query=None): |
| """\ |
| Like query_objects, but return a list of dictionaries. |
| """ |
| query = cls.query_objects(filter_data, initial_query=initial_query) |
| extra_fields = query.query.extra_select.keys() |
| field_dicts = [model_object.get_object_dict(extra_fields=extra_fields) |
| for model_object in query] |
| return field_dicts |
| |
| |
| @classmethod |
| def smart_get(cls, id_or_name, valid_only=True): |
| """\ |
| smart_get(integer) -> get object by ID |
| smart_get(string) -> get object by name_field |
| """ |
| if valid_only: |
| manager = cls.get_valid_manager() |
| else: |
| manager = cls.objects |
| |
| if isinstance(id_or_name, (int, long)): |
| return manager.get(pk=id_or_name) |
| if isinstance(id_or_name, basestring): |
| return manager.get(**{cls.name_field : id_or_name}) |
| raise ValueError( |
| 'Invalid positional argument: %s (%s)' % (id_or_name, |
| type(id_or_name))) |
| |
| |
| @classmethod |
| def smart_get_bulk(cls, id_or_name_list): |
| invalid_inputs = [] |
| result_objects = [] |
| for id_or_name in id_or_name_list: |
| try: |
| result_objects.append(cls.smart_get(id_or_name)) |
| except cls.DoesNotExist: |
| invalid_inputs.append(id_or_name) |
| if invalid_inputs: |
| raise cls.DoesNotExist('The following %ss do not exist: %s' |
| % (cls.__name__.lower(), |
| ', '.join(invalid_inputs))) |
| return result_objects |
| |
| |
| def get_object_dict(self, extra_fields=None): |
| """\ |
| Return a dictionary mapping fields to this object's values. @param |
| extra_fields: list of extra attribute names to include, in addition to |
| the fields defined on this object. |
| """ |
| fields = self.get_field_dict().keys() |
| if extra_fields: |
| fields += extra_fields |
| object_dict = dict((field_name, getattr(self, field_name)) |
| for field_name in fields) |
| self.clean_object_dicts([object_dict]) |
| self._postprocess_object_dict(object_dict) |
| return object_dict |
| |
| |
| def _postprocess_object_dict(self, object_dict): |
| """For subclasses to override.""" |
| pass |
| |
| |
| @classmethod |
| def get_valid_manager(cls): |
| return cls.objects |
| |
| |
| def _record_attributes(self, attributes): |
| """ |
| See on_attribute_changed. |
| """ |
| assert not isinstance(attributes, basestring) |
| self._recorded_attributes = dict((attribute, getattr(self, attribute)) |
| for attribute in attributes) |
| |
| |
| def _check_for_updated_attributes(self): |
| """ |
| See on_attribute_changed. |
| """ |
| for attribute, original_value in self._recorded_attributes.iteritems(): |
| new_value = getattr(self, attribute) |
| if original_value != new_value: |
| self.on_attribute_changed(attribute, original_value) |
| self._record_attributes(self._recorded_attributes.keys()) |
| |
| |
| def on_attribute_changed(self, attribute, old_value): |
| """ |
| Called whenever an attribute is updated. To be overridden. |
| |
| To use this method, you must: |
| * call _record_attributes() from __init__() (after making the super |
| call) with a list of attributes for which you want to be notified upon |
| change. |
| * call _check_for_updated_attributes() from save(). |
| """ |
| pass |
| |
| |
| class ModelWithInvalid(ModelExtensions): |
| """ |
| Overrides model methods save() and delete() to support invalidation in |
| place of actual deletion. Subclasses must have a boolean "invalid" |
| field. |
| """ |
| |
| def save(self, *args, **kwargs): |
| first_time = (self.id is None) |
| if first_time: |
| # see if this object was previously added and invalidated |
| my_name = getattr(self, self.name_field) |
| filters = {self.name_field : my_name, 'invalid' : True} |
| try: |
| old_object = self.__class__.objects.get(**filters) |
| self.resurrect_object(old_object) |
| except self.DoesNotExist: |
| # no existing object |
| pass |
| |
| super(ModelWithInvalid, self).save(*args, **kwargs) |
| |
| |
| def resurrect_object(self, old_object): |
| """ |
| Called when self is about to be saved for the first time and is actually |
| "undeleting" a previously deleted object. Can be overridden by |
| subclasses to copy data as desired from the deleted entry (but this |
| superclass implementation must normally be called). |
| """ |
| self.id = old_object.id |
| |
| |
| def clean_object(self): |
| """ |
| This method is called when an object is marked invalid. |
| Subclasses should override this to clean up relationships that |
| should no longer exist if the object were deleted. |
| """ |
| pass |
| |
| |
| def delete(self): |
| assert not self.invalid |
| self.invalid = True |
| self.save() |
| self.clean_object() |
| |
| |
| @classmethod |
| def get_valid_manager(cls): |
| return cls.valid_objects |
| |
| |
| class Manipulator(object): |
| """ |
| Force default manipulators to look only at valid objects - |
| otherwise they will match against invalid objects when checking |
| uniqueness. |
| """ |
| @classmethod |
| def _prepare(cls, model): |
| super(ModelWithInvalid.Manipulator, cls)._prepare(model) |
| cls.manager = model.valid_objects |
| |
| |
| class ModelWithAttributes(object): |
| """ |
| Mixin class for models that have an attribute model associated with them. |
| The attribute model is assumed to have its value field named "value". |
| """ |
| |
| def _get_attribute_model_and_args(self, attribute): |
| """ |
| Subclasses should override this to return a tuple (attribute_model, |
| keyword_args), where attribute_model is a model class and keyword_args |
| is a dict of args to pass to attribute_model.objects.get() to get an |
| instance of the given attribute on this object. |
| """ |
| raise NotImplemented |
| |
| |
| def set_attribute(self, attribute, value): |
| attribute_model, get_args = self._get_attribute_model_and_args( |
| attribute) |
| attribute_object, _ = attribute_model.objects.get_or_create(**get_args) |
| attribute_object.value = value |
| attribute_object.save() |
| |
| |
| def delete_attribute(self, attribute): |
| attribute_model, get_args = self._get_attribute_model_and_args( |
| attribute) |
| try: |
| attribute_model.objects.get(**get_args).delete() |
| except attribute_model.DoesNotExist: |
| pass |
| |
| |
| def set_or_delete_attribute(self, attribute, value): |
| if value is None: |
| self.delete_attribute(attribute) |
| else: |
| self.set_attribute(attribute, value) |
| |
| |
| class ModelWithHashManager(dbmodels.Manager): |
| """Manager for use with the ModelWithHash abstract model class""" |
| |
| def create(self, **kwargs): |
| raise Exception('ModelWithHash manager should use get_or_create() ' |
| 'instead of create()') |
| |
| |
| def get_or_create(self, **kwargs): |
| kwargs['the_hash'] = self.model._compute_hash(**kwargs) |
| return super(ModelWithHashManager, self).get_or_create(**kwargs) |
| |
| |
| class ModelWithHash(dbmodels.Model): |
| """Superclass with methods for dealing with a hash column""" |
| |
| the_hash = dbmodels.CharField(max_length=40, unique=True) |
| |
| objects = ModelWithHashManager() |
| |
| class Meta: |
| abstract = True |
| |
| |
| @classmethod |
| def _compute_hash(cls, **kwargs): |
| raise NotImplementedError('Subclasses must override _compute_hash()') |
| |
| |
| def save(self, force_insert=False, **kwargs): |
| """Prevents saving the model in most cases |
| |
| We want these models to be immutable, so the generic save() operation |
| will not work. These models should be instantiated through their the |
| model.objects.get_or_create() method instead. |
| |
| The exception is that save(force_insert=True) will be allowed, since |
| that creates a new row. However, the preferred way to make instances of |
| these models is through the get_or_create() method. |
| """ |
| if not force_insert: |
| # Allow a forced insert to happen; if it's a duplicate, the unique |
| # constraint will catch it later anyways |
| raise Exception('ModelWithHash is immutable') |
| super(ModelWithHash, self).save(force_insert=force_insert, **kwargs) |