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251 lines
8.2 KiB
Python
251 lines
8.2 KiB
Python
"""CSV to database or vice versa."""
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import csv
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import pkg_resources
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import sys
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from sqlalchemy.orm.attributes import instrumentation_registry
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import sqlalchemy.types
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from pokedex.db import metadata
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import pokedex.db.tables as tables
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def _get_verbose_prints(verbose):
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"""If `verbose` is true, returns two functions: one for printing a starting
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message, and the other for printing a success or failure message when
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finished.
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If `verbose` is false, returns two no-op functions.
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"""
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if verbose:
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import sys
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def print_start(thing):
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# Truncate to 66 characters, leaving 10 characters for a success
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# or failure message
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truncated_thing = thing[0:66]
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# Also, space-pad to keep the cursor in a known column
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num_spaces = 66 - len(truncated_thing)
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print "%s...%s" % (truncated_thing, ' ' * num_spaces),
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sys.stdout.flush()
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def print_done(msg='ok'):
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print msg
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sys.stdout.flush()
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return print_start, print_done
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# Not verbose; return dummies
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def dummy(*args, **kwargs):
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pass
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return dummy, dummy
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def load(session, directory=None, drop_tables=False, verbose=False):
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"""Load data from CSV files into the given database session.
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Tables are created automatically.
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`session`
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SQLAlchemy session to use.
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`directory`
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Directory the CSV files reside in. Defaults to the `pokedex` data
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directory.
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`drop_tables`
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If set to True, existing `pokedex`-related tables will be dropped.
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`verbose`
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If set to True, status messages will be printed to stdout.
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"""
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# First take care of verbosity
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print_start, print_done = _get_verbose_prints(verbose)
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if not directory:
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directory = pkg_resources.resource_filename('pokedex', 'data/csv')
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# Drop all tables if requested
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if drop_tables:
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print_start('Dropping tables')
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metadata.drop_all()
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print_done()
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metadata.create_all()
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# SQLAlchemy is retarded and there is no way for me to get a list of ORM
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# classes besides to inspect the module they all happen to live in for
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# things that look right.
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table_base = tables.TableBase
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orm_classes = {} # table object => table class
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for name in dir(tables):
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# dir() returns strings! How /convenient/.
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thingy = getattr(tables, name)
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if not isinstance(thingy, type):
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# Not a class; bail
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continue
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elif not issubclass(thingy, table_base):
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# Not a declarative table; bail
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continue
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elif thingy == table_base:
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# Declarative table base, so not a real table; bail
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continue
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# thingy is definitely a table class! Hallelujah.
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orm_classes[thingy.__table__] = thingy
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# Okay, run through the tables and actually load the data now
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for table_obj in metadata.sorted_tables:
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table_class = orm_classes[table_obj]
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table_name = table_obj.name
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print_start(table_name)
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try:
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csvfile = open("%s/%s.csv" % (directory, table_name), 'rb')
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except IOError:
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# File doesn't exist; don't load anything!
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print_done('missing?')
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continue
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reader = csv.reader(csvfile, lineterminator='\n')
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column_names = [unicode(column) for column in reader.next()]
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# Self-referential tables may contain rows with foreign keys of other
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# rows in the same table that do not yet exist. Pull these out and add
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# them to the session last
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# ASSUMPTION: Self-referential tables have a single PK called "id"
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deferred_rows = [] # ( row referring to id, [foreign ids we need] )
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seen_ids = {} # primary key we've seen => 1
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# Fetch foreign key columns that point at this table, if any
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self_ref_columns = []
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for column in table_obj.c:
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if any(_.references(table_obj) for _ in column.foreign_keys):
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self_ref_columns.append(column)
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for csvs in reader:
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row = table_class()
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for column_name, value in zip(column_names, csvs):
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column = table_obj.c[column_name]
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if column.nullable and value == '':
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# Empty string in a nullable column really means NULL
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value = None
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elif isinstance(column.type, sqlalchemy.types.Boolean):
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# Boolean values are stored as string values 0/1, but both
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# of those evaluate as true; SQLA wants True/False
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if value == '0':
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value = False
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else:
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value = True
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else:
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# Otherwise, unflatten from bytes
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value = value.decode('utf-8')
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setattr(row, column_name, value)
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# May need to stash this row and add it later if it refers to a
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# later row in this table
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if self_ref_columns:
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foreign_ids = [getattr(row, _.name) for _ in self_ref_columns]
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foreign_ids = [_ for _ in foreign_ids if _] # remove NULL ids
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if not foreign_ids:
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# NULL key. Remember this row and add as usual.
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seen_ids[row.id] = 1
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elif all(_ in seen_ids for _ in foreign_ids):
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# Non-NULL key we've already seen. Remember it and commit
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# so we know the old row exists when we add the new one
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session.commit()
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seen_ids[row.id] = 1
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else:
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# Non-NULL future id. Save this and insert it later!
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deferred_rows.append((row, foreign_ids))
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continue
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session.add(row)
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# Remembering some zillion rows in the session consumes a lot of
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# RAM. Let's not do that. Commit every 1000 rows
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if len(session.new) > 1000:
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session.commit()
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session.commit()
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# Attempt to add any spare rows we've collected
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for row, foreign_ids in deferred_rows:
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if not all(_ in seen_ids for _ in foreign_ids):
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# Could happen if row A refers to B which refers to C.
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# This is ridiculous and doesn't happen in my data so far
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raise ValueError("Too many levels of self-reference! "
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"Row was: " + str(row.__dict__))
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session.add(row)
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seen_ids[row.id] = 1
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session.commit()
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print_done()
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def dump(session, directory=None, verbose=False):
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"""Dumps the contents of a database to a set of CSV files. Probably not
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useful to anyone besides a developer.
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`session`
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SQLAlchemy session to use.
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`directory`
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Directory the CSV files should be put in. Defaults to the `pokedex`
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data directory.
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`verbose`
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If set to True, status messages will be printed to stdout.
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"""
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# First take care of verbosity
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print_start, print_done = _get_verbose_prints(verbose)
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if not directory:
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directory = pkg_resources.resource_filename('pokedex', 'data/csv')
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for table_name in sorted(metadata.tables.keys()):
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print_start(table_name)
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table = metadata.tables[table_name]
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writer = csv.writer(open("%s/%s.csv" % (directory, table_name), 'wb'),
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lineterminator='\n')
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columns = [col.name for col in table.columns]
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writer.writerow(columns)
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primary_key = table.primary_key
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for row in session.query(table).order_by(*primary_key).all():
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csvs = []
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for col in columns:
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# Convert Pythony values to something more universal
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val = getattr(row, col)
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if val == None:
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val = ''
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elif val == True:
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val = '1'
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elif val == False:
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val = '0'
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else:
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val = unicode(val).encode('utf-8')
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csvs.append(val)
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writer.writerow(csvs)
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print_done()
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