X-Git-Url: http://git.veekun.com/zzz-pokedex.git/blobdiff_plain/14ac0c55489ad42f1cfac3a254ab0e4778c00a35..6af0c42ed6234d8db295b8bf3811fbacac75dbc6:/pokedex/db/load.py?ds=sidebyside diff --git a/pokedex/db/load.py b/pokedex/db/load.py new file mode 100644 index 0000000..1cff39d --- /dev/null +++ b/pokedex/db/load.py @@ -0,0 +1,197 @@ +"""CSV to database or vice versa.""" +import csv +import pkg_resources +import sys + +from sqlalchemy.orm.attributes import instrumentation_registry +import sqlalchemy.types + +from pokedex.db import metadata +import pokedex.db.tables as tables + + +def load(session, directory=None, drop_tables=False): + """Load data from CSV files into the given database session. + + Tables are created automatically. + + `session` + SQLAlchemy session to use. + + `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. + """ + + if not directory: + directory = pkg_resources.resource_filename('pokedex', 'data/csv') + + # Drop all tables if requested + if options.drop_tables: + print 'Dropping tables...' + metadata.drop_all() + + metadata.create_all() + + # SQLAlchemy is retarded and there is no way for me to get a list of ORM + # classes besides to inspect the module they all happen to live in for + # things that look right. + table_base = tables.TableBase + orm_classes = {} # table object => table class + + for name in dir(tables): + # dir() returns strings! How /convenient/. + thingy = getattr(tables, name) + + if not isinstance(thingy, type): + # Not a class; bail + continue + elif not issubclass(thingy, table_base): + # Not a declarative table; bail + continue + elif thingy == table_base: + # Declarative table base, so not a real table; bail + continue + + # thingy is definitely a table class! Hallelujah. + orm_classes[thingy.__table__] = thingy + + # Okay, run through the tables and actually load the data now + for table_obj in metadata.sorted_tables: + table_class = orm_classes[table_obj] + table_name = table_obj.name + + # Print the table name but leave the cursor in a fixed column + print table_name + '...', ' ' * (40 - len(table_name)), + sys.stdout.flush() + + try: + csvfile = open("%s/%s.csv" % (directory, table_name), 'rb') + except IOError: + # File doesn't exist; don't load anything! + print 'no data!' + continue + + 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) + + for csvs in reader: + row = table_class() + + 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') + + setattr(row, 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 = [getattr(row, _.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.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 + session.commit() + seen_ids[row.id] = 1 + + else: + # Non-NULL future id. Save this and insert it later! + deferred_rows.append((row, foreign_ids)) + continue + + session.add(row) + + session.commit() + + # Attempt to add any spare rows we've collected + for row, 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.__dict__)) + + session.add(row) + seen_ids[row.id] = 1 + session.commit() + + print 'loaded' + + + +def dump(session, directory=None): + """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. + + `directory` + Directory the CSV files should be put in. Defaults to the `pokedex` + data directory. + """ + + if not directory: + directory = pkg_resources.resource_filename('pokedex', 'data/csv') + + for table_name in sorted(metadata.tables.keys()): + print 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)