"""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 _get_verbose_prints(verbose):
"""If `verbose` is true, returns two functions: one for printing a starting
message, and the other for printing a success or failure message when
finished.
If `verbose` is false, returns two no-op functions.
"""
if verbose:
import sys
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()
def print_done(msg='ok'):
print msg
sys.stdout.flush()
return print_start, print_done
# Not verbose; return dummies
def dummy(*args, **kwargs):
pass
return dummy, dummy
def load(session, 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.
`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_done = _get_verbose_prints(verbose)
if not directory:
directory = pkg_resources.resource_filename('pokedex', 'data/csv')
# Drop all tables if requested
if drop_tables:
print_start('Dropping tables')
metadata.drop_all()
print_done()
metadata.create_all()
connection = session.connection()
# Okay, run through the tables and actually load the data now
for table_obj in metadata.sorted_tables:
table_name = table_obj.name
insert_stmt = table_obj.insert()
print_start(table_name)
try:
csvfile = open("%s/%s.csv" % (directory, table_name), 'rb')
except IOError:
# File doesn't exist; don't load anything!
print_done('missing?')
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)
new_rows = []
def insert_and_commit():
session.connection().execute(insert_stmt, new_rows)
session.commit()
new_rows[:] = []
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, 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.
`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_done = _get_verbose_prints(verbose)
if not directory:
directory = pkg_resources.resource_filename('pokedex', 'data/csv')
for table_name in sorted(metadata.tables.keys()):
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()