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416 lines
12 KiB
416 lines
12 KiB
import csv
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import datetime
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from decimal import Decimal
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import json
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import operator
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try:
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from urlparse import urlparse
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except ImportError:
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from urllib.parse import urlparse
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import sys
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from peewee import *
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from playhouse.db_url import connect
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from playhouse.migrate import migrate
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from playhouse.migrate import SchemaMigrator
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from playhouse.reflection import Introspector
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if sys.version_info[0] == 3:
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basestring = str
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from functools import reduce
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def open_file(f, mode):
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return open(f, mode, encoding='utf8')
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else:
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open_file = open
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class DataSet(object):
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def __init__(self, url, bare_fields=False):
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if isinstance(url, Database):
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self._url = None
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self._database = url
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self._database_path = self._database.database
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else:
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self._url = url
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parse_result = urlparse(url)
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self._database_path = parse_result.path[1:]
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# Connect to the database.
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self._database = connect(url)
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self._database.connect()
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# Introspect the database and generate models.
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self._introspector = Introspector.from_database(self._database)
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self._models = self._introspector.generate_models(
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skip_invalid=True,
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literal_column_names=True,
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bare_fields=bare_fields)
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self._migrator = SchemaMigrator.from_database(self._database)
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class BaseModel(Model):
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class Meta:
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database = self._database
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self._base_model = BaseModel
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self._export_formats = self.get_export_formats()
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self._import_formats = self.get_import_formats()
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def __repr__(self):
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return '<DataSet: %s>' % self._database_path
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def get_export_formats(self):
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return {
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'csv': CSVExporter,
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'json': JSONExporter}
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def get_import_formats(self):
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return {
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'csv': CSVImporter,
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'json': JSONImporter}
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def __getitem__(self, table):
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if table not in self._models and table in self.tables:
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self.update_cache(table)
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return Table(self, table, self._models.get(table))
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@property
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def tables(self):
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return self._database.get_tables()
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def __contains__(self, table):
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return table in self.tables
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def connect(self):
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self._database.connect()
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def close(self):
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self._database.close()
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def update_cache(self, table=None):
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if table:
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dependencies = [table]
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if table in self._models:
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model_class = self._models[table]
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dependencies.extend([
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related._meta.table_name for _, related, _ in
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model_class._meta.model_graph()])
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else:
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dependencies.extend(self.get_table_dependencies(table))
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else:
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dependencies = None # Update all tables.
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self._models = {}
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updated = self._introspector.generate_models(
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skip_invalid=True,
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table_names=dependencies,
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literal_column_names=True)
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self._models.update(updated)
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def get_table_dependencies(self, table):
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stack = [table]
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accum = []
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seen = set()
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while stack:
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table = stack.pop()
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for fk_meta in self._database.get_foreign_keys(table):
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dest = fk_meta.dest_table
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if dest not in seen:
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stack.append(dest)
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accum.append(dest)
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return accum
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def __enter__(self):
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self.connect()
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return self
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def __exit__(self, exc_type, exc_val, exc_tb):
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if not self._database.is_closed():
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self.close()
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def query(self, sql, params=None, commit=True):
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return self._database.execute_sql(sql, params, commit)
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def transaction(self):
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if self._database.transaction_depth() == 0:
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return self._database.transaction()
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else:
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return self._database.savepoint()
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def _check_arguments(self, filename, file_obj, format, format_dict):
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if filename and file_obj:
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raise ValueError('file is over-specified. Please use either '
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'filename or file_obj, but not both.')
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if not filename and not file_obj:
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raise ValueError('A filename or file-like object must be '
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'specified.')
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if format not in format_dict:
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valid_formats = ', '.join(sorted(format_dict.keys()))
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raise ValueError('Unsupported format "%s". Use one of %s.' % (
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format, valid_formats))
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def freeze(self, query, format='csv', filename=None, file_obj=None,
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**kwargs):
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self._check_arguments(filename, file_obj, format, self._export_formats)
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if filename:
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file_obj = open_file(filename, 'w')
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exporter = self._export_formats[format](query)
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exporter.export(file_obj, **kwargs)
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if filename:
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file_obj.close()
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def thaw(self, table, format='csv', filename=None, file_obj=None,
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strict=False, **kwargs):
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self._check_arguments(filename, file_obj, format, self._export_formats)
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if filename:
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file_obj = open_file(filename, 'r')
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importer = self._import_formats[format](self[table], strict)
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count = importer.load(file_obj, **kwargs)
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if filename:
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file_obj.close()
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return count
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class Table(object):
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def __init__(self, dataset, name, model_class):
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self.dataset = dataset
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self.name = name
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if model_class is None:
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model_class = self._create_model()
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model_class.create_table()
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self.dataset._models[name] = model_class
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@property
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def model_class(self):
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return self.dataset._models[self.name]
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def __repr__(self):
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return '<Table: %s>' % self.name
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def __len__(self):
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return self.find().count()
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def __iter__(self):
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return iter(self.find().iterator())
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def _create_model(self):
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class Meta:
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table_name = self.name
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return type(
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str(self.name),
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(self.dataset._base_model,),
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{'Meta': Meta})
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def create_index(self, columns, unique=False):
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self.dataset._database.create_index(
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self.model_class,
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columns,
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unique=unique)
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def _guess_field_type(self, value):
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if isinstance(value, basestring):
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return TextField
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if isinstance(value, (datetime.date, datetime.datetime)):
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return DateTimeField
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elif value is True or value is False:
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return BooleanField
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elif isinstance(value, int):
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return IntegerField
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elif isinstance(value, float):
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return FloatField
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elif isinstance(value, Decimal):
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return DecimalField
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return TextField
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@property
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def columns(self):
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return [f.name for f in self.model_class._meta.sorted_fields]
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def _migrate_new_columns(self, data):
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new_keys = set(data) - set(self.model_class._meta.fields)
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if new_keys:
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operations = []
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for key in new_keys:
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field_class = self._guess_field_type(data[key])
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field = field_class(null=True)
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operations.append(
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self.dataset._migrator.add_column(self.name, key, field))
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field.bind(self.model_class, key)
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migrate(*operations)
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self.dataset.update_cache(self.name)
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def insert(self, **data):
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self._migrate_new_columns(data)
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return self.model_class.insert(**data).execute()
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def _apply_where(self, query, filters, conjunction=None):
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conjunction = conjunction or operator.and_
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if filters:
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expressions = [
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(self.model_class._meta.fields[column] == value)
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for column, value in filters.items()]
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query = query.where(reduce(conjunction, expressions))
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return query
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def update(self, columns=None, conjunction=None, **data):
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self._migrate_new_columns(data)
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filters = {}
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if columns:
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for column in columns:
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filters[column] = data.pop(column)
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return self._apply_where(
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self.model_class.update(**data),
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filters,
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conjunction).execute()
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def _query(self, **query):
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return self._apply_where(self.model_class.select(), query)
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def find(self, **query):
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return self._query(**query).dicts()
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def find_one(self, **query):
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try:
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return self.find(**query).get()
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except self.model_class.DoesNotExist:
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return None
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def all(self):
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return self.find()
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def delete(self, **query):
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return self._apply_where(self.model_class.delete(), query).execute()
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def freeze(self, *args, **kwargs):
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return self.dataset.freeze(self.all(), *args, **kwargs)
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def thaw(self, *args, **kwargs):
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return self.dataset.thaw(self.name, *args, **kwargs)
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class Exporter(object):
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def __init__(self, query):
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self.query = query
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def export(self, file_obj):
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raise NotImplementedError
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class JSONExporter(Exporter):
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def __init__(self, query, iso8601_datetimes=False):
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super(JSONExporter, self).__init__(query)
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self.iso8601_datetimes = iso8601_datetimes
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def _make_default(self):
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datetime_types = (datetime.datetime, datetime.date, datetime.time)
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if self.iso8601_datetimes:
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def default(o):
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if isinstance(o, datetime_types):
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return o.isoformat()
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elif isinstance(o, Decimal):
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return str(o)
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raise TypeError('Unable to serialize %r as JSON' % o)
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else:
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def default(o):
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if isinstance(o, datetime_types + (Decimal,)):
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return str(o)
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raise TypeError('Unable to serialize %r as JSON' % o)
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return default
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def export(self, file_obj, **kwargs):
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json.dump(
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list(self.query),
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file_obj,
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default=self._make_default(),
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**kwargs)
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class CSVExporter(Exporter):
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def export(self, file_obj, header=True, **kwargs):
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writer = csv.writer(file_obj, **kwargs)
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tuples = self.query.tuples().execute()
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tuples.initialize()
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if header and getattr(tuples, 'columns', None):
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writer.writerow([column for column in tuples.columns])
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for row in tuples:
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writer.writerow(row)
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class Importer(object):
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def __init__(self, table, strict=False):
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self.table = table
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self.strict = strict
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model = self.table.model_class
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self.columns = model._meta.columns
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self.columns.update(model._meta.fields)
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def load(self, file_obj):
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raise NotImplementedError
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class JSONImporter(Importer):
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def load(self, file_obj, **kwargs):
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data = json.load(file_obj, **kwargs)
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count = 0
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for row in data:
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if self.strict:
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obj = {}
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for key in row:
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field = self.columns.get(key)
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if field is not None:
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obj[field.name] = field.python_value(row[key])
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else:
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obj = row
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if obj:
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self.table.insert(**obj)
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count += 1
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return count
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class CSVImporter(Importer):
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def load(self, file_obj, header=True, **kwargs):
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count = 0
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reader = csv.reader(file_obj, **kwargs)
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if header:
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try:
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header_keys = next(reader)
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except StopIteration:
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return count
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if self.strict:
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header_fields = []
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for idx, key in enumerate(header_keys):
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if key in self.columns:
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header_fields.append((idx, self.columns[key]))
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else:
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header_fields = list(enumerate(header_keys))
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else:
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header_fields = list(enumerate(self.model._meta.sorted_fields))
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if not header_fields:
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return count
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for row in reader:
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obj = {}
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for idx, field in header_fields:
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if self.strict:
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obj[field.name] = field.python_value(row[idx])
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else:
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obj[field] = row[idx]
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self.table.insert(**obj)
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count += 1
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return count
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