import functools import logging import traceback from collections import OrderedDict from copy import deepcopy import tablib from diff_match_patch import diff_match_patch from django.conf import settings from django.core.exceptions import ( FieldDoesNotExist, ImproperlyConfigured, ValidationError, ) from django.core.management.color import no_style from django.core.paginator import Paginator from django.db import connections, router from django.db.models.fields.related import ForeignObjectRel from django.db.models.query import QuerySet from django.db.transaction import ( TransactionManagementError, savepoint, savepoint_commit, savepoint_rollback, ) from django.utils.encoding import force_str from django.utils.safestring import mark_safe from . import widgets from .fields import Field from .instance_loaders import ModelInstanceLoader from .results import Error, Result, RowResult from .utils import atomic_if_using_transaction logger = logging.getLogger(__name__) # Set default logging handler to avoid "No handler found" warnings. logger.addHandler(logging.NullHandler()) def get_related_model(field): if hasattr(field, 'related_model'): return field.related_model def has_natural_foreign_key(model): """ Determine if a model has natural foreign key functions """ return (hasattr(model, "natural_key") and hasattr(model.objects, "get_by_natural_key")) class ResourceOptions: """ The inner Meta class allows for class-level configuration of how the Resource should behave. The following options are available: """ model = None """ Django Model class. It is used to introspect available fields. """ fields = None """ Controls what introspected fields the Resource should include. A whitelist of fields. """ exclude = None """ Controls what introspected fields the Resource should NOT include. A blacklist of fields. """ instance_loader_class = None """ Controls which class instance will take care of loading existing objects. """ import_id_fields = ['id'] """ Controls which object fields will be used to identify existing instances. """ export_order = None """ Controls export order for columns. """ widgets = None """ This dictionary defines widget kwargs for fields. """ use_transactions = None """ Controls if import should use database transactions. Default value is ``None`` meaning ``settings.IMPORT_EXPORT_USE_TRANSACTIONS`` will be evaluated. """ skip_unchanged = False """ Controls if the import should skip unchanged records. Default value is False """ report_skipped = True """ Controls if the result reports skipped rows. Default value is True """ clean_model_instances = False """ Controls whether ``instance.full_clean()`` is called during the import process to identify potential validation errors for each (non skipped) row. The default value is False. """ chunk_size = None """ Controls the chunk_size argument of Queryset.iterator or, if prefetch_related is used, the per_page attribute of Paginator. """ skip_diff = False """ Controls whether or not an instance should be diffed following import. By default, an instance is copied prior to insert, update or delete. After each row is processed, the instance's copy is diffed against the original, and the value stored in each ``RowResult``. If diffing is not required, then disabling the diff operation by setting this value to ``True`` improves performance, because the copy and comparison operations are skipped for each row. If enabled, then ``skip_row()`` checks do not execute, because 'skip' logic requires comparison between the stored and imported versions of a row. If enabled, then HTML row reports are also not generated (see ``skip_html_diff``). The default value is False. """ skip_html_diff = False """ Controls whether or not a HTML report is generated after each row. By default, the difference between a stored copy and an imported instance is generated in HTML form and stored in each ``RowResult``. The HTML report is used to present changes on the confirmation screen in the admin site, hence when this value is ``True``, then changes will not be presented on the confirmation screen. If the HTML report is not required, then setting this value to ``True`` improves performance, because the HTML generation is skipped for each row. This is a useful optimization when importing large datasets. The default value is False. """ use_bulk = False """ Controls whether import operations should be performed in bulk. By default, an object's save() method is called for each row in a data set. When bulk is enabled, objects are saved using bulk operations. """ batch_size = 1000 """ The batch_size parameter controls how many objects are created in a single query. The default is to create objects in batches of 1000. See `bulk_create() `_. This parameter is only used if ``use_bulk`` is True. """ force_init_instance = False """ If True, this parameter will prevent imports from checking the database for existing instances. Enabling this parameter is a performance enhancement if your import dataset is guaranteed to contain new instances. """ using_db = None """ DB Connection name to use for db transactions. If not provided, ``router.db_for_write(model)`` will be evaluated and if it's missing, DEFAULT_DB_ALIAS constant ("default") is used. """ store_row_values = False """ If True, each row's raw data will be stored in each row result. Enabling this parameter will increase the memory usage during import which should be considered when importing large datasets. """ use_natural_foreign_keys = False """ If True, use_natural_foreign_keys = True will be passed to all foreign key widget fields whose models support natural foreign keys. That is, the model has a natural_key function and the manager has a get_by_natural_key function. """ class DeclarativeMetaclass(type): def __new__(cls, name, bases, attrs): declared_fields = [] meta = ResourceOptions() # If this class is subclassing another Resource, add that Resource's # fields. Note that we loop over the bases in *reverse*. This is # necessary in order to preserve the correct order of fields. for base in bases[::-1]: if hasattr(base, 'fields'): declared_fields = list(base.fields.items()) + declared_fields # Collect the Meta options options = getattr(base, 'Meta', None) for option in [option for option in dir(options) if not option.startswith('_') and hasattr(options, option)]: setattr(meta, option, getattr(options, option)) # Add direct fields for field_name, obj in attrs.copy().items(): if isinstance(obj, Field): field = attrs.pop(field_name) if not field.column_name: field.column_name = field_name declared_fields.append((field_name, field)) attrs['fields'] = OrderedDict(declared_fields) new_class = super().__new__(cls, name, bases, attrs) # Add direct options options = getattr(new_class, 'Meta', None) for option in [option for option in dir(options) if not option.startswith('_') and hasattr(options, option)]: setattr(meta, option, getattr(options, option)) new_class._meta = meta return new_class class Diff: def __init__(self, resource, instance, new): self.left = self._export_resource_fields(resource, instance) self.right = [] self.new = new def compare_with(self, resource, instance, dry_run=False): self.right = self._export_resource_fields(resource, instance) def as_html(self): data = [] dmp = diff_match_patch() for v1, v2 in zip(self.left, self.right): if v1 != v2 and self.new: v1 = "" diff = dmp.diff_main(force_str(v1), force_str(v2)) dmp.diff_cleanupSemantic(diff) html = dmp.diff_prettyHtml(diff) html = mark_safe(html) data.append(html) return data def _export_resource_fields(self, resource, instance): return [resource.export_field(f, instance) if instance else "" for f in resource.get_user_visible_fields()] class Resource(metaclass=DeclarativeMetaclass): """ Resource defines how objects are mapped to their import and export representations and handle importing and exporting data. """ def __init__(self): # The fields class attribute is the *class-wide* definition of # fields. Because a particular *instance* of the class might want to # alter self.fields, we create self.fields here by copying cls.fields. # Instances should always modify self.fields; they should not modify # cls.fields. self.fields = deepcopy(self.fields) # lists to hold model instances in memory when bulk operations are enabled self.create_instances = list() self.update_instances = list() self.delete_instances = list() @classmethod def get_result_class(self): """ Returns the class used to store the result of an import. """ return Result @classmethod def get_row_result_class(self): """ Returns the class used to store the result of a row import. """ return RowResult @classmethod def get_error_result_class(self): """ Returns the class used to store an error resulting from an import. """ return Error @classmethod def get_diff_class(self): """ Returns the class used to display the diff for an imported instance. """ return Diff def get_db_connection_name(self): if self._meta.using_db is None: return router.db_for_write(self._meta.model) else: return self._meta.using_db def get_use_transactions(self): if self._meta.use_transactions is None: return getattr(settings, 'IMPORT_EXPORT_USE_TRANSACTIONS', True) else: return self._meta.use_transactions def get_chunk_size(self): if self._meta.chunk_size is None: return getattr(settings, 'IMPORT_EXPORT_CHUNK_SIZE', 100) else: return self._meta.chunk_size def get_fields(self, **kwargs): """ Returns fields sorted according to :attr:`~import_export.resources.ResourceOptions.export_order`. """ return [self.fields[f] for f in self.get_export_order()] def get_field_name(self, field): """ Returns the field name for a given field. """ for field_name, f in self.fields.items(): if f == field: return field_name raise AttributeError("Field %s does not exists in %s resource" % ( field, self.__class__)) def init_instance(self, row=None): """ Initializes an object. Implemented in :meth:`import_export.resources.ModelResource.init_instance`. """ raise NotImplementedError() def get_instance(self, instance_loader, row): """ If all 'import_id_fields' are present in the dataset, calls the :doc:`InstanceLoader `. Otherwise, returns `None`. """ import_id_fields = [ self.fields[f] for f in self.get_import_id_fields() ] for field in import_id_fields: if field.column_name not in row: return return instance_loader.get_instance(row) def get_or_init_instance(self, instance_loader, row): """ Either fetches an already existing instance or initializes a new one. """ if not self._meta.force_init_instance: instance = self.get_instance(instance_loader, row) if instance: return (instance, False) return (self.init_instance(row), True) def get_import_id_fields(self): """ """ return self._meta.import_id_fields def get_bulk_update_fields(self): """ Returns the fields to be included in calls to bulk_update(). ``import_id_fields`` are removed because `id` fields cannot be supplied to bulk_update(). """ return [f for f in self.fields if f not in self._meta.import_id_fields] def bulk_create(self, using_transactions, dry_run, raise_errors, batch_size=None): """ Creates objects by calling ``bulk_create``. """ try: if len(self.create_instances) > 0: if not using_transactions and dry_run: pass else: self._meta.model.objects.bulk_create(self.create_instances, batch_size=batch_size) except Exception as e: logger.exception(e) if raise_errors: raise e finally: self.create_instances.clear() def bulk_update(self, using_transactions, dry_run, raise_errors, batch_size=None): """ Updates objects by calling ``bulk_update``. """ try: if len(self.update_instances) > 0: if not using_transactions and dry_run: pass else: self._meta.model.objects.bulk_update(self.update_instances, self.get_bulk_update_fields(), batch_size=batch_size) except Exception as e: logger.exception(e) if raise_errors: raise e finally: self.update_instances.clear() def bulk_delete(self, using_transactions, dry_run, raise_errors): """ Deletes objects by filtering on a list of instances to be deleted, then calling ``delete()`` on the entire queryset. """ try: if len(self.delete_instances) > 0: if not using_transactions and dry_run: pass else: delete_ids = [o.pk for o in self.delete_instances] self._meta.model.objects.filter(pk__in=delete_ids).delete() except Exception as e: logger.exception(e) if raise_errors: raise e finally: self.delete_instances.clear() def validate_instance(self, instance, import_validation_errors=None, validate_unique=True): """ Takes any validation errors that were raised by :meth:`~import_export.resources.Resource.import_obj`, and combines them with validation errors raised by the instance's ``full_clean()`` method. The combined errors are then re-raised as single, multi-field ValidationError. If the ``clean_model_instances`` option is False, the instances's ``full_clean()`` method is not called, and only the errors raised by ``import_obj()`` are re-raised. """ if import_validation_errors is None: errors = {} else: errors = import_validation_errors.copy() if self._meta.clean_model_instances: try: instance.full_clean( exclude=errors.keys(), validate_unique=validate_unique, ) except ValidationError as e: errors = e.update_error_dict(errors) if errors: raise ValidationError(errors) def save_instance(self, instance, is_create, using_transactions=True, dry_run=False): """ Takes care of saving the object to the database. Objects can be created in bulk if ``use_bulk`` is enabled. :param instance: The instance of the object to be persisted. :param is_create: A boolean flag to indicate whether this is a new object to be created, or an existing object to be updated. :param using_transactions: A flag to indicate whether db transactions are used. :param dry_run: A flag to indicate dry-run mode. """ self.before_save_instance(instance, using_transactions, dry_run) if self._meta.use_bulk: if is_create: self.create_instances.append(instance) else: self.update_instances.append(instance) else: if not using_transactions and dry_run: # we don't have transactions and we want to do a dry_run pass else: instance.save() self.after_save_instance(instance, using_transactions, dry_run) def before_save_instance(self, instance, using_transactions, dry_run): """ Override to add additional logic. Does nothing by default. """ pass def after_save_instance(self, instance, using_transactions, dry_run): """ Override to add additional logic. Does nothing by default. """ pass def delete_instance(self, instance, using_transactions=True, dry_run=False): """ Calls :meth:`instance.delete` as long as ``dry_run`` is not set. If ``use_bulk`` then instances are appended to a list for bulk import. """ self.before_delete_instance(instance, dry_run) if self._meta.use_bulk: self.delete_instances.append(instance) else: if not using_transactions and dry_run: # we don't have transactions and we want to do a dry_run pass else: instance.delete() self.after_delete_instance(instance, dry_run) def before_delete_instance(self, instance, dry_run): """ Override to add additional logic. Does nothing by default. """ pass def after_delete_instance(self, instance, dry_run): """ Override to add additional logic. Does nothing by default. """ pass def import_field(self, field, obj, data, is_m2m=False, **kwargs): """ Calls :meth:`import_export.fields.Field.save` if ``Field.attribute`` is specified, and ``Field.column_name`` is found in ``data``. """ if field.attribute and field.column_name in data: field.save(obj, data, is_m2m, **kwargs) def get_import_fields(self): return self.get_fields() def import_obj(self, obj, data, dry_run, **kwargs): """ Traverses every field in this Resource and calls :meth:`~import_export.resources.Resource.import_field`. If ``import_field()`` results in a ``ValueError`` being raised for one of more fields, those errors are captured and reraised as a single, multi-field ValidationError.""" errors = {} for field in self.get_import_fields(): if isinstance(field.widget, widgets.ManyToManyWidget): continue try: self.import_field(field, obj, data, **kwargs) except ValueError as e: errors[field.attribute] = ValidationError( force_str(e), code="invalid") if errors: raise ValidationError(errors) def save_m2m(self, obj, data, using_transactions, dry_run): """ Saves m2m fields. Model instance need to have a primary key value before a many-to-many relationship can be used. """ if (not using_transactions and dry_run) or self._meta.use_bulk: # we don't have transactions and we want to do a dry_run # OR use_bulk is enabled (m2m operations are not supported for bulk operations) pass else: for field in self.get_import_fields(): if not isinstance(field.widget, widgets.ManyToManyWidget): continue self.import_field(field, obj, data, True) def for_delete(self, row, instance): """ Returns ``True`` if ``row`` importing should delete instance. Default implementation returns ``False``. Override this method to handle deletion. """ return False def skip_row(self, instance, original, row, import_validation_errors=None): """ Returns ``True`` if ``row`` importing should be skipped. Default implementation returns ``False`` unless skip_unchanged == True and skip_diff == False. If skip_diff is True, then no comparisons can be made because ``original`` will be None. When left unspecified, skip_diff and skip_unchanged both default to ``False``, and rows are never skipped. By default, rows are not skipped if validation errors have been detected during import. You can change this behavior and choose to ignore validation errors by overriding this method. Override this method to handle skipping rows meeting certain conditions. Use ``super`` if you want to preserve default handling while overriding :: class YourResource(ModelResource): def skip_row(self, instance, original, row, import_validation_errors=None): # Add code here return super().skip_row(instance, original, row, import_validation_errors=import_validation_errors) """ if not self._meta.skip_unchanged or self._meta.skip_diff or import_validation_errors: return False for field in self.get_import_fields(): # For fields that are models.fields.related.ManyRelatedManager # we need to compare the results if isinstance(field.widget, widgets.ManyToManyWidget): # #1437 - handle m2m field not present in import file if field.column_name not in row.keys(): continue # m2m instance values are taken from the 'row' because they # have not been written to the 'instance' at this point instance_values = list(field.clean(row)) original_values = list(field.get_value(original).all()) if len(instance_values) != len(original_values): return False if sorted(v.pk for v in instance_values) != sorted(v.pk for v in original_values): return False else: if field.get_value(instance) != field.get_value(original): return False return True def get_diff_headers(self): """ Diff representation headers. """ return self.get_user_visible_headers() def before_import(self, dataset, using_transactions, dry_run, **kwargs): """ Override to add additional logic. Does nothing by default. """ pass def after_import(self, dataset, result, using_transactions, dry_run, **kwargs): """ Override to add additional logic. Does nothing by default. """ pass def before_import_row(self, row, row_number=None, **kwargs): """ Override to add additional logic. Does nothing by default. """ pass def after_import_row(self, row, row_result, row_number=None, **kwargs): """ Override to add additional logic. Does nothing by default. """ pass def after_import_instance(self, instance, new, row_number=None, **kwargs): """ Override to add additional logic. Does nothing by default. """ pass def import_row(self, row, instance_loader, using_transactions=True, dry_run=False, raise_errors=False, **kwargs): """ Imports data from ``tablib.Dataset``. Refer to :doc:`import_workflow` for a more complete description of the whole import process. :param row: A ``dict`` of the row to import :param instance_loader: The instance loader to be used to load the row :param using_transactions: If ``using_transactions`` is set, a transaction is being used to wrap the import :param dry_run: If ``dry_run`` is set, or error occurs, transaction will be rolled back. """ skip_diff = self._meta.skip_diff row_result = self.get_row_result_class()() if self._meta.store_row_values: row_result.row_values = row original = None try: self.before_import_row(row, **kwargs) instance, new = self.get_or_init_instance(instance_loader, row) self.after_import_instance(instance, new, **kwargs) if new: row_result.import_type = RowResult.IMPORT_TYPE_NEW else: row_result.import_type = RowResult.IMPORT_TYPE_UPDATE row_result.new_record = new if not skip_diff: original = deepcopy(instance) diff = self.get_diff_class()(self, original, new) if self.for_delete(row, instance): if new: row_result.import_type = RowResult.IMPORT_TYPE_SKIP if not skip_diff: diff.compare_with(self, None, dry_run) else: row_result.import_type = RowResult.IMPORT_TYPE_DELETE row_result.add_instance_info(instance) self.delete_instance(instance, using_transactions, dry_run) if not skip_diff: diff.compare_with(self, None, dry_run) else: import_validation_errors = {} try: self.import_obj(instance, row, dry_run, **kwargs) except ValidationError as e: # Validation errors from import_obj() are passed on to # validate_instance(), where they can be combined with model # instance validation errors if necessary import_validation_errors = e.update_error_dict(import_validation_errors) if self.skip_row(instance, original, row, import_validation_errors): row_result.import_type = RowResult.IMPORT_TYPE_SKIP else: self.validate_instance(instance, import_validation_errors) self.save_instance(instance, new, using_transactions, dry_run) self.save_m2m(instance, row, using_transactions, dry_run) row_result.add_instance_info(instance) if not skip_diff: diff.compare_with(self, instance, dry_run) if not skip_diff and not self._meta.skip_html_diff: row_result.diff = diff.as_html() self.after_import_row(row, row_result, **kwargs) except ValidationError as e: row_result.import_type = RowResult.IMPORT_TYPE_INVALID row_result.validation_error = e except Exception as e: row_result.import_type = RowResult.IMPORT_TYPE_ERROR # There is no point logging a transaction error for each row # when only the original error is likely to be relevant if not isinstance(e, TransactionManagementError): logger.debug(e, exc_info=e) tb_info = traceback.format_exc() row_result.errors.append(self.get_error_result_class()(e, tb_info, row)) if self._meta.use_bulk: # persist a batch of rows # because this is a batch, any exceptions are logged and not associated # with a specific row if len(self.create_instances) == self._meta.batch_size: self.bulk_create(using_transactions, dry_run, raise_errors, batch_size=self._meta.batch_size) if len(self.update_instances) == self._meta.batch_size: self.bulk_update(using_transactions, dry_run, raise_errors, batch_size=self._meta.batch_size) if len(self.delete_instances) == self._meta.batch_size: self.bulk_delete(using_transactions, dry_run, raise_errors) return row_result def import_data(self, dataset, dry_run=False, raise_errors=False, use_transactions=None, collect_failed_rows=False, rollback_on_validation_errors=False, **kwargs): """ Imports data from ``tablib.Dataset``. Refer to :doc:`import_workflow` for a more complete description of the whole import process. :param dataset: A ``tablib.Dataset`` :param raise_errors: Whether errors should be printed to the end user or raised regularly. :param use_transactions: If ``True`` the import process will be processed inside a transaction. :param collect_failed_rows: If ``True`` the import process will collect failed rows. :param rollback_on_validation_errors: If both ``use_transactions`` and ``rollback_on_validation_errors`` are set to ``True``, the import process will be rolled back in case of ValidationError. :param dry_run: If ``dry_run`` is set, or an error occurs, if a transaction is being used, it will be rolled back. """ if use_transactions is None: use_transactions = self.get_use_transactions() db_connection = self.get_db_connection_name() connection = connections[db_connection] supports_transactions = getattr(connection.features, "supports_transactions", False) if use_transactions and not supports_transactions: raise ImproperlyConfigured using_transactions = (use_transactions or dry_run) and supports_transactions if self._meta.batch_size is not None and (not isinstance(self._meta.batch_size, int) or self._meta.batch_size < 0): raise ValueError("Batch size must be a positive integer") with atomic_if_using_transaction(using_transactions, using=db_connection): return self.import_data_inner( dataset, dry_run, raise_errors, using_transactions, collect_failed_rows, rollback_on_validation_errors, **kwargs) def import_data_inner( self, dataset, dry_run, raise_errors, using_transactions, collect_failed_rows, rollback_on_validation_errors=False, **kwargs): result = self.get_result_class()() result.diff_headers = self.get_diff_headers() result.total_rows = len(dataset) db_connection = self.get_db_connection_name() if using_transactions: # when transactions are used we want to create/update/delete object # as transaction will be rolled back if dry_run is set sp1 = savepoint(using=db_connection) try: with atomic_if_using_transaction(using_transactions, using=db_connection): self.before_import(dataset, using_transactions, dry_run, **kwargs) except Exception as e: logger.debug(e, exc_info=e) tb_info = traceback.format_exc() result.append_base_error(self.get_error_result_class()(e, tb_info)) if raise_errors: raise instance_loader = self._meta.instance_loader_class(self, dataset) # Update the total in case the dataset was altered by before_import() result.total_rows = len(dataset) if collect_failed_rows: result.add_dataset_headers(dataset.headers) for i, row in enumerate(dataset.dict, 1): with atomic_if_using_transaction(using_transactions, using=db_connection): row_result = self.import_row( row, instance_loader, using_transactions=using_transactions, dry_run=dry_run, row_number=i, raise_errors=raise_errors, **kwargs ) result.increment_row_result_total(row_result) if row_result.errors: if collect_failed_rows: result.append_failed_row(row, row_result.errors[0]) if raise_errors: raise row_result.errors[-1].error elif row_result.validation_error: result.append_invalid_row(i, row, row_result.validation_error) if collect_failed_rows: result.append_failed_row(row, row_result.validation_error) if raise_errors: raise row_result.validation_error if (row_result.import_type != RowResult.IMPORT_TYPE_SKIP or self._meta.report_skipped): result.append_row_result(row_result) if self._meta.use_bulk: # bulk persist any instances which are still pending with atomic_if_using_transaction(using_transactions, using=db_connection): self.bulk_create(using_transactions, dry_run, raise_errors) self.bulk_update(using_transactions, dry_run, raise_errors) self.bulk_delete(using_transactions, dry_run, raise_errors) try: with atomic_if_using_transaction(using_transactions, using=db_connection): self.after_import(dataset, result, using_transactions, dry_run, **kwargs) except Exception as e: logger.debug(e, exc_info=e) tb_info = traceback.format_exc() result.append_base_error(self.get_error_result_class()(e, tb_info)) if raise_errors: raise if using_transactions: if dry_run or \ result.has_errors() or \ (rollback_on_validation_errors and result.has_validation_errors()): savepoint_rollback(sp1, using=db_connection) else: savepoint_commit(sp1, using=db_connection) return result def get_export_order(self): order = tuple(self._meta.export_order or ()) return order + tuple(k for k in self.fields if k not in order) def before_export(self, queryset, *args, **kwargs): """ Override to add additional logic. Does nothing by default. """ pass def after_export(self, queryset, data, *args, **kwargs): """ Override to add additional logic. Does nothing by default. """ pass def export_field(self, field, obj): field_name = self.get_field_name(field) method = getattr(self, 'dehydrate_%s' % field_name, None) if method is not None: return method(obj) return field.export(obj) def get_export_fields(self): return self.get_fields() def export_resource(self, obj): return [self.export_field(field, obj) for field in self.get_export_fields()] def get_export_headers(self): headers = [ force_str(field.column_name) for field in self.get_export_fields()] return headers def get_user_visible_headers(self): headers = [ force_str(field.column_name) for field in self.get_user_visible_fields()] return headers def get_user_visible_fields(self): return self.get_fields() def iter_queryset(self, queryset): if not isinstance(queryset, QuerySet): yield from queryset elif queryset._prefetch_related_lookups: # Django's queryset.iterator ignores prefetch_related which might result # in an excessive amount of db calls. Therefore we use pagination # as a work-around if not queryset.query.order_by: # Paginator() throws a warning if there is no sorting # attached to the queryset queryset = queryset.order_by('pk') paginator = Paginator(queryset, self.get_chunk_size()) for index in range(paginator.num_pages): yield from paginator.get_page(index + 1) else: yield from queryset.iterator(chunk_size=self.get_chunk_size()) def export(self, queryset=None, *args, **kwargs): """ Exports a resource. """ self.before_export(queryset, *args, **kwargs) if queryset is None: queryset = self.get_queryset() headers = self.get_export_headers() data = tablib.Dataset(headers=headers) for obj in self.iter_queryset(queryset): data.append(self.export_resource(obj)) self.after_export(queryset, data, *args, **kwargs) return data class ModelDeclarativeMetaclass(DeclarativeMetaclass): def __new__(cls, name, bases, attrs): new_class = super().__new__(cls, name, bases, attrs) opts = new_class._meta if not opts.instance_loader_class: opts.instance_loader_class = ModelInstanceLoader if opts.model: model_opts = opts.model._meta declared_fields = new_class.fields field_list = [] for f in sorted(model_opts.fields + model_opts.many_to_many): if opts.fields is not None and not f.name in opts.fields: continue if opts.exclude and f.name in opts.exclude: continue if f.name in declared_fields: continue field = new_class.field_from_django_field(f.name, f, readonly=False) field_list.append((f.name, field, )) new_class.fields.update(OrderedDict(field_list)) # add fields that follow relationships if opts.fields is not None: field_list = [] for field_name in opts.fields: if field_name in declared_fields: continue if field_name.find('__') == -1: continue model = opts.model attrs = field_name.split('__') for i, attr in enumerate(attrs): verbose_path = ".".join([opts.model.__name__] + attrs[0:i+1]) try: f = model._meta.get_field(attr) except FieldDoesNotExist as e: logger.debug(e, exc_info=e) raise FieldDoesNotExist( "%s: %s has no field named '%s'" % (verbose_path, model.__name__, attr)) if i < len(attrs) - 1: # We're not at the last attribute yet, so check # that we're looking at a relation, and move on to # the next model. if isinstance(f, ForeignObjectRel): model = get_related_model(f) else: if get_related_model(f) is None: raise KeyError( '%s is not a relation' % verbose_path) model = get_related_model(f) if isinstance(f, ForeignObjectRel): f = f.field field = new_class.field_from_django_field(field_name, f, readonly=True) field_list.append((field_name, field)) new_class.fields.update(OrderedDict(field_list)) return new_class class ModelResource(Resource, metaclass=ModelDeclarativeMetaclass): """ ModelResource is Resource subclass for handling Django models. """ DEFAULT_RESOURCE_FIELD = Field WIDGETS_MAP = { 'ManyToManyField': 'get_m2m_widget', 'OneToOneField': 'get_fk_widget', 'ForeignKey': 'get_fk_widget', 'CharField': widgets.CharWidget, 'DecimalField': widgets.DecimalWidget, 'DateTimeField': widgets.DateTimeWidget, 'DateField': widgets.DateWidget, 'TimeField': widgets.TimeWidget, 'DurationField': widgets.DurationWidget, 'FloatField': widgets.FloatWidget, 'IntegerField': widgets.IntegerWidget, 'PositiveIntegerField': widgets.IntegerWidget, 'BigIntegerField': widgets.IntegerWidget, 'PositiveSmallIntegerField': widgets.IntegerWidget, 'SmallIntegerField': widgets.IntegerWidget, 'SmallAutoField': widgets.IntegerWidget, 'AutoField': widgets.IntegerWidget, 'BigAutoField': widgets.IntegerWidget, 'NullBooleanField': widgets.BooleanWidget, 'BooleanField': widgets.BooleanWidget, 'JSONField': widgets.JSONWidget, } @classmethod def get_m2m_widget(cls, field): """ Prepare widget for m2m field """ return functools.partial( widgets.ManyToManyWidget, model=get_related_model(field)) @classmethod def get_fk_widget(cls, field): """ Prepare widget for fk and o2o fields """ model = get_related_model(field) use_natural_foreign_keys = ( has_natural_foreign_key(model) and cls._meta.use_natural_foreign_keys ) return functools.partial( widgets.ForeignKeyWidget, model=model, use_natural_foreign_keys=use_natural_foreign_keys) @classmethod def widget_from_django_field(cls, f, default=widgets.Widget): """ Returns the widget that would likely be associated with each Django type. Includes mapping of Postgres Array field. In the case that psycopg2 is not installed, we consume the error and process the field regardless. """ result = default internal_type = "" if callable(getattr(f, "get_internal_type", None)): internal_type = f.get_internal_type() if internal_type in cls.WIDGETS_MAP: result = cls.WIDGETS_MAP[internal_type] if isinstance(result, str): result = getattr(cls, result)(f) else: try: from django.contrib.postgres.fields import ArrayField except ImportError: # ImportError: No module named psycopg2.extras class ArrayField: pass if isinstance(f, ArrayField): return widgets.SimpleArrayWidget return result @classmethod def widget_kwargs_for_field(self, field_name): """ Returns widget kwargs for given field_name. """ if self._meta.widgets: return self._meta.widgets.get(field_name, {}) return {} @classmethod def field_from_django_field(cls, field_name, django_field, readonly): """ Returns a Resource Field instance for the given Django model field. """ FieldWidget = cls.widget_from_django_field(django_field) widget_kwargs = cls.widget_kwargs_for_field(field_name) field = cls.DEFAULT_RESOURCE_FIELD( attribute=field_name, column_name=field_name, widget=FieldWidget(**widget_kwargs), readonly=readonly, default=django_field.default, ) return field def get_queryset(self): """ Returns a queryset of all objects for this model. Override this if you want to limit the returned queryset. """ return self._meta.model.objects.all() def init_instance(self, row=None): """ Initializes a new Django model. """ return self._meta.model() def after_import(self, dataset, result, using_transactions, dry_run, **kwargs): """ Reset the SQL sequences after new objects are imported """ # Adapted from django's loaddata if not dry_run and any(r.import_type == RowResult.IMPORT_TYPE_NEW for r in result.rows): db_connection = self.get_db_connection_name() connection = connections[db_connection] sequence_sql = connection.ops.sequence_reset_sql(no_style(), [self._meta.model]) if sequence_sql: cursor = connection.cursor() try: for line in sequence_sql: cursor.execute(line) finally: cursor.close() @classmethod def get_display_name(cls): if hasattr(cls._meta, 'name'): return cls._meta.name return cls.__name__ def modelresource_factory(model, resource_class=ModelResource): """ Factory for creating ``ModelResource`` class for given Django model. """ attrs = {'model': model} Meta = type(str('Meta'), (object,), attrs) class_name = model.__name__ + str('Resource') class_attrs = { 'Meta': Meta, } metaclass = ModelDeclarativeMetaclass return metaclass(class_name, (resource_class,), class_attrs)