+"""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)
projects / zzz-pokedex.git / commitdiff
