"""CSV to database or vice versa.""" import csv import os.path import pkg_resources import re import sys from sqlalchemy.orm.attributes import instrumentation_registry import sqlalchemy.sql.util import sqlalchemy.types from pokedex.db import metadata import pokedex.db.tables as tables def _wildcard_char_to_regex(char): """Converts a single wildcard character to the regex equivalent.""" if char == '?': return '.?' elif char == '*': return '.*' else: return re.escape(char) def _wildcard_glob_to_regex(glob): """Converts a single wildcard glob to a regex STRING.""" # If it looks like a filename, make it not one if '.' in glob or '/' in glob: _, filename = os.path.split(glob) table_name, _ = os.path.splitext(filename) glob = table_name return u''.join(map(_wildcard_char_to_regex, glob)) def _wildcards_to_regex(strings): """Converts a list of wildcard globs to a single regex object.""" regex_parts = map(_wildcard_glob_to_regex, strings) regex = '^(?:' + '|'.join(regex_parts) + ')$' return re.compile(regex) def _get_verbose_prints(verbose): """If `verbose` is true, returns three functions: one for printing a starting message, one for printing an interim status update, and one for printing a success or failure message when finished. If `verbose` is false, returns no-op functions. """ if not verbose: # Return dummies def dummy(*args, **kwargs): pass return dummy, dummy, dummy ### Okay, verbose == True; print stuff def print_start(thing): # Truncate to 66 characters, leaving 10 characters for a success # or failure message truncated_thing = thing[0:66] # Also, space-pad to keep the cursor in a known column num_spaces = 66 - len(truncated_thing) print "%s...%s" % (truncated_thing, ' ' * num_spaces), sys.stdout.flush() if sys.stdout.isatty(): # stdout is a terminal; stupid backspace tricks are OK. # Don't use print, because it always adds magical spaces, which # makes backspace accounting harder backspaces = [0] def print_status(msg): # Overwrite any status text with spaces before printing sys.stdout.write('\b' * backspaces[0]) sys.stdout.write(' ' * backspaces[0]) sys.stdout.write('\b' * backspaces[0]) sys.stdout.write(msg) sys.stdout.flush() backspaces[0] = len(msg) def print_done(msg='ok'): # Overwrite any status text with spaces before printing sys.stdout.write('\b' * backspaces[0]) sys.stdout.write(' ' * backspaces[0]) sys.stdout.write('\b' * backspaces[0]) sys.stdout.write(msg + "\n") sys.stdout.flush() backspaces[0] = 0 else: # stdout is a file (or something); don't bother with status at all def print_status(msg): pass def print_done(msg='ok'): print msg return print_start, print_status, print_done def load(session, tables=[], directory=None, drop_tables=False, verbose=False): """Load data from CSV files into the given database session. Tables are created automatically. `session` SQLAlchemy session to use. `tables` List of tables to load. If omitted, all tables are loaded. `directory` Directory the CSV files reside in. Defaults to the `pokedex` data directory. `drop_tables` If set to True, existing `pokedex`-related tables will be dropped. `verbose` If set to True, status messages will be printed to stdout. """ # First take care of verbosity print_start, print_status, print_done = _get_verbose_prints(verbose) if not directory: directory = pkg_resources.resource_filename('pokedex', 'data/csv') if tables: regex = _wildcards_to_regex(tables) table_names = filter(regex.match, metadata.tables.keys()) else: table_names = metadata.tables.keys() table_objs = [metadata.tables[name] for name in table_names] table_objs = sqlalchemy.sql.util.sort_tables(table_objs) # Drop all tables if requested if drop_tables: print_start('Dropping tables') for table in reversed(table_objs): table.drop(checkfirst=True) print_done() for table in table_objs: table.create() connection = session.connection() # Okay, run through the tables and actually load the data now for table_obj in table_objs: table_name = table_obj.name insert_stmt = table_obj.insert() print_start(table_name) try: csvpath = "%s/%s.csv" % (directory, table_name) csvfile = open(csvpath, 'rb') except IOError: # File doesn't exist; don't load anything! print_done('missing?') continue csvsize = os.stat(csvpath).st_size reader = csv.reader(csvfile, lineterminator='\n') column_names = [unicode(column) for column in reader.next()] # Self-referential tables may contain rows with foreign keys of other # rows in the same table that do not yet exist. Pull these out and add # them to the session last # ASSUMPTION: Self-referential tables have a single PK called "id" deferred_rows = [] # ( row referring to id, [foreign ids we need] ) seen_ids = {} # primary key we've seen => 1 # Fetch foreign key columns that point at this table, if any self_ref_columns = [] for column in table_obj.c: if any(_.references(table_obj) for _ in column.foreign_keys): self_ref_columns.append(column) new_rows = [] def insert_and_commit(): session.connection().execute(insert_stmt, new_rows) session.commit() new_rows[:] = [] progress = "{0}%".format(100 * csvfile.tell() // csvsize) print_status(progress) for csvs in reader: row_data = {} for column_name, value in zip(column_names, csvs): column = table_obj.c[column_name] if column.nullable and value == '': # Empty string in a nullable column really means NULL value = None elif isinstance(column.type, sqlalchemy.types.Boolean): # Boolean values are stored as string values 0/1, but both # of those evaluate as true; SQLA wants True/False if value == '0': value = False else: value = True else: # Otherwise, unflatten from bytes value = value.decode('utf-8') # nb: Dictionaries flattened with ** have to have string keys row_data[ str(column_name) ] = value # May need to stash this row and add it later if it refers to a # later row in this table if self_ref_columns: foreign_ids = [row_data[_.name] for _ in self_ref_columns] foreign_ids = [_ for _ in foreign_ids if _] # remove NULL ids if not foreign_ids: # NULL key. Remember this row and add as usual. seen_ids[row_data['id']] = 1 elif all(_ in seen_ids for _ in foreign_ids): # Non-NULL key we've already seen. Remember it and commit # so we know the old row exists when we add the new one insert_and_commit() seen_ids[row_data['id']] = 1 else: # Non-NULL future id. Save this and insert it later! deferred_rows.append((row_data, foreign_ids)) continue # Insert row! new_rows.append(row_data) # Remembering some zillion rows in the session consumes a lot of # RAM. Let's not do that. Commit every 1000 rows if len(new_rows) >= 1000: insert_and_commit() insert_and_commit() # Attempt to add any spare rows we've collected for row_data, foreign_ids in deferred_rows: if not all(_ in seen_ids for _ in foreign_ids): # Could happen if row A refers to B which refers to C. # This is ridiculous and doesn't happen in my data so far raise ValueError("Too many levels of self-reference! " "Row was: " + str(row)) session.connection().execute( insert_stmt.values(**row_data) ) seen_ids[row_data['id']] = 1 session.commit() print_done() def dump(session, tables=[], directory=None, verbose=False): """Dumps the contents of a database to a set of CSV files. Probably not useful to anyone besides a developer. `session` SQLAlchemy session to use. `tables` List of tables to dump. If omitted, all tables are dumped. `directory` Directory the CSV files should be put in. Defaults to the `pokedex` data directory. `verbose` If set to True, status messages will be printed to stdout. """ # First take care of verbosity print_start, print_status, print_done = _get_verbose_prints(verbose) if not directory: directory = pkg_resources.resource_filename('pokedex', 'data/csv') if tables: regex = _wildcards_to_regex(tables) table_names = filter(regex.match, metadata.tables.keys()) else: table_names = metadata.tables.keys() table_names.sort() for table_name in table_names: print_start(table_name) table = metadata.tables[table_name] writer = csv.writer(open("%s/%s.csv" % (directory, table_name), 'wb'), lineterminator='\n') columns = [col.name for col in table.columns] writer.writerow(columns) primary_key = table.primary_key for row in session.query(table).order_by(*primary_key).all(): csvs = [] for col in columns: # Convert Pythony values to something more universal val = getattr(row, col) if val == None: val = '' elif val == True: val = '1' elif val == False: val = '0' else: val = unicode(val).encode('utf-8') csvs.append(val) writer.writerow(csvs) print_done()