from types import StringTypes import time import calendar from PLC.Faults import * from PLC.Parameter import Parameter class Row(dict): """ Representation of a row in a database table. To use, optionally instantiate with a dict of values. Update as you would a dict. Commit to the database with sync(). """ # Set this to the name of the table that stores the row. table_name = None # Set this to the name of the primary key of the table. It is # assumed that the this key is a sequence if it is not set when # sync() is called. primary_key = None # Set this to the names of tables that reference this table's # primary key. join_tables = [] # Set this to a dict of the valid fields of this object and their # types. Not all fields (e.g., joined fields) may be updated via # sync(). fields = {} def __init__(self, api, fields = {}): dict.__init__(self, fields) self.api = api def validate(self): """ Validates values. Will validate a value with a custom function if a function named 'validate_[key]' exists. """ # Warn about mandatory fields mandatory_fields = self.api.db.fields(self.table_name, notnull = True, hasdef = False) for field in mandatory_fields: if not self.has_key(field) or self[field] is None: raise PLCInvalidArgument, field + " must be specified and cannot be unset in class %s"%self.__class__.__name__ # Validate values before committing for key, value in self.iteritems(): if value is not None and hasattr(self, 'validate_' + key): validate = getattr(self, 'validate_' + key) self[key] = validate(value) def separate_types(self, items): """ Separate a list of different typed objects. Return a list for each type (ints, strs and dicts) """ if isinstance(items, (list, tuple, set)): ints = filter(lambda x: isinstance(x, (int, long)), items) strs = filter(lambda x: isinstance(x, StringTypes), items) dicts = filter(lambda x: isinstance(x, dict), items) return (ints, strs, dicts) else: raise PLCInvalidArgument, "Can only separate list types" def associate(self, *args): """ Provides a means for high lvl api calls to associate objects using low lvl calls. """ if len(args) < 3: raise PLCInvalidArgumentCount, "auth, field, value must be specified" elif hasattr(self, 'associate_' + args[1]): associate = getattr(self, 'associate_'+args[1]) associate(*args) else: raise PLCInvalidArguemnt, "No such associate function associate_%s" % args[1] def validate_timestamp(self, timestamp, check_future = False): """ Validates the specified GMT timestamp string (must be in %Y-%m-%d %H:%M:%S format) or number (seconds since UNIX epoch, i.e., 1970-01-01 00:00:00 GMT). If check_future is True, raises an exception if timestamp is not in the future. Returns a GMT timestamp string. """ time_format = "%Y-%m-%d %H:%M:%S" if isinstance(timestamp, StringTypes): # calendar.timegm() is the inverse of time.gmtime() timestamp = calendar.timegm(time.strptime(timestamp, time_format)) # Human readable timestamp string human = time.strftime(time_format, time.gmtime(timestamp)) if check_future and timestamp < time.time(): raise PLCInvalidArgument, "'%s' not in the future" % human return human def add_object(self, classobj, join_table, columns = None): """ Returns a function that can be used to associate this object with another. """ def add(self, obj, columns = None, commit = True): """ Associate with the specified object. """ # Various sanity checks assert isinstance(self, Row) assert self.primary_key in self assert join_table in self.join_tables assert isinstance(obj, classobj) assert isinstance(obj, Row) assert obj.primary_key in obj assert join_table in obj.join_tables # By default, just insert the primary keys of each object # into the join table. if columns is None: columns = {self.primary_key: self[self.primary_key], obj.primary_key: obj[obj.primary_key]} params = [] for name, value in columns.iteritems(): params.append(self.api.db.param(name, value)) self.api.db.do("INSERT INTO %s (%s) VALUES(%s)" % \ (join_table, ", ".join(columns), ", ".join(params)), columns) if commit: self.api.db.commit() return add add_object = classmethod(add_object) def remove_object(self, classobj, join_table): """ Returns a function that can be used to disassociate this object with another. """ def remove(self, obj, commit = True): """ Disassociate from the specified object. """ assert isinstance(self, Row) assert self.primary_key in self assert join_table in self.join_tables assert isinstance(obj, classobj) assert isinstance(obj, Row) assert obj.primary_key in obj assert join_table in obj.join_tables self_id = self[self.primary_key] obj_id = obj[obj.primary_key] self.api.db.do("DELETE FROM %s WHERE %s = %s AND %s = %s" % \ (join_table, self.primary_key, self.api.db.param('self_id', self_id), obj.primary_key, self.api.db.param('obj_id', obj_id)), locals()) if commit: self.api.db.commit() return remove remove_object = classmethod(remove_object) def db_fields(self, obj = None): """ Return only those fields that can be set or updated directly (i.e., those fields that are in the primary table (table_name) for this object, and are not marked as a read-only Parameter. """ if obj is None: obj = self db_fields = self.api.db.fields(self.table_name) return dict(filter(lambda (key, value): \ key in db_fields and \ (key not in self.fields or \ not isinstance(self.fields[key], Parameter) or \ not self.fields[key].ro), obj.items())) def __eq__(self, y): """ Compare two objects. """ # Filter out fields that cannot be set or updated directly # (and thus would not affect equality for the purposes of # deciding if we should sync() or not). x = self.db_fields() y = self.db_fields(y) return dict.__eq__(x, y) def sync(self, commit = True, insert = None): """ Flush changes back to the database. """ # Validate all specified fields self.validate() # Filter out fields that cannot be set or updated directly db_fields = self.db_fields() # Parameterize for safety keys = db_fields.keys() values = [self.api.db.param(key, value) for (key, value) in db_fields.items()] # If the primary key (usually an auto-incrementing serial # identifier) has not been specified, or the primary key is the # only field in the table, or insert has been forced. if not self.has_key(self.primary_key) or \ keys == [self.primary_key] or \ insert is True: # Insert new row sql = "INSERT INTO %s (%s) VALUES (%s)" % \ (self.table_name, ", ".join(keys), ", ".join(values)) else: # Update existing row columns = ["%s = %s" % (key, value) for (key, value) in zip(keys, values)] sql = "UPDATE %s SET " % self.table_name + \ ", ".join(columns) + \ " WHERE %s = %s" % \ (self.primary_key, self.api.db.param(self.primary_key, self[self.primary_key])) self.api.db.do(sql, db_fields) if not self.has_key(self.primary_key): self[self.primary_key] = self.api.db.last_insert_id(self.table_name, self.primary_key) if commit: self.api.db.commit() def delete(self, commit = True): """ Delete row from its primary table, and from any tables that reference it. """ assert self.primary_key in self for table in self.join_tables + [self.table_name]: if isinstance(table, tuple): key = table[1] table = table[0] else: key = self.primary_key sql = "DELETE FROM %s WHERE %s = %s" % \ (table, key, self.api.db.param(self.primary_key, self[self.primary_key])) self.api.db.do(sql, self) if commit: self.api.db.commit() class Table(list): """ Representation of row(s) in a database table. """ def __init__(self, api, classobj, columns = None): self.api = api self.classobj = classobj self.rows = {} if columns is None: columns = classobj.fields else: columns = filter(lambda x: x in classobj.fields, columns) if not columns: raise PLCInvalidArgument, "No valid return fields specified" self.columns = columns def sync(self, commit = True): """ Flush changes back to the database. """ for row in self: row.sync(commit) def selectall(self, sql, params = None): """ Given a list of rows from the database, fill ourselves with Row objects. """ for row in self.api.db.selectall(sql, params): obj = self.classobj(self.api, row) self.append(obj) def dict(self, key_field = None): """ Return ourself as a dict keyed on key_field. """ if key_field is None: key_field = self.classobj.primary_key return dict([(obj[key_field], obj) for obj in self])