pokedex/db/load.py

   1 """CSV to database or vice versa."""
   2 import csv
   3 import fnmatch
   4 import os.path
   5 import sys
   6
   7 from sqlalchemy.orm.attributes import instrumentation_registry
   8 import sqlalchemy.sql.util
   9 import sqlalchemy.types
  10
  11 from pokedex.db import metadata
  12 import pokedex.db.tables as tables
  13 from pokedex.defaults import get_default_csv_dir
  14
  15
  16 def _get_table_names(metadata, patterns):
  17     """Returns a list of table names from the given metadata.  If `patterns`
  18     exists, only tables matching one of the patterns will be returned.
  19     """
  20     if patterns:
  21         table_names = set()
  22         for pattern in patterns:
  23             if '.' in pattern or '/' in pattern:
  24                 # If it looks like a filename, pull out just the table name
  25                 _, filename = os.path.split(pattern)
  26                 table_name, _ = os.path.splitext(filename)
  27                 pattern = table_name
  28
  29             table_names.update(fnmatch.filter(metadata.tables.keys(), pattern))
  30     else:
  31         table_names = metadata.tables.keys()
  32
  33     return list(table_names)
  34
  35 def _get_verbose_prints(verbose):
  36     """If `verbose` is true, returns three functions: one for printing a
  37     starting message, one for printing an interim status update, and one for
  38     printing a success or failure message when finished.
  39
  40     If `verbose` is false, returns no-op functions.
  41     """
  42
  43     if not verbose:
  44         # Return dummies
  45         def dummy(*args, **kwargs):
  46             pass
  47
  48         return dummy, dummy, dummy
  49
  50     ### Okay, verbose == True; print stuff
  51
  52     def print_start(thing):
  53         # Truncate to 66 characters, leaving 10 characters for a success
  54         # or failure message
  55         truncated_thing = thing[0:66]
  56
  57         # Also, space-pad to keep the cursor in a known column
  58         num_spaces = 66 - len(truncated_thing)
  59
  60         print "%s...%s" % (truncated_thing, ' ' * num_spaces),
  61         sys.stdout.flush()
  62
  63     if sys.stdout.isatty():
  64         # stdout is a terminal; stupid backspace tricks are OK.
  65         # Don't use print, because it always adds magical spaces, which
  66         # makes backspace accounting harder
  67
  68         backspaces = [0]
  69         def print_status(msg):
  70             # Overwrite any status text with spaces before printing
  71             sys.stdout.write('\b' * backspaces[0])
  72             sys.stdout.write(' ' * backspaces[0])
  73             sys.stdout.write('\b' * backspaces[0])
  74             sys.stdout.write(msg)
  75             sys.stdout.flush()
  76             backspaces[0] = len(msg)
  77
  78         def print_done(msg='ok'):
  79             # Overwrite any status text with spaces before printing
  80             sys.stdout.write('\b' * backspaces[0])
  81             sys.stdout.write(' ' * backspaces[0])
  82             sys.stdout.write('\b' * backspaces[0])
  83             sys.stdout.write(msg + "\n")
  84             sys.stdout.flush()
  85             backspaces[0] = 0
  86
  87     else:
  88         # stdout is a file (or something); don't bother with status at all
  89         def print_status(msg):
  90             pass
  91
  92         def print_done(msg='ok'):
  93             print msg
  94
  95     return print_start, print_status, print_done
  96
  97
  98 def load(session, tables=[], directory=None, drop_tables=False, verbose=False, safe=True):
  99     """Load data from CSV files into the given database session.
 100
 101     Tables are created automatically.
 102
 103     `session`
 104         SQLAlchemy session to use.
 105
 106     `tables`
 107         List of tables to load.  If omitted, all tables are loaded.
 108
 109     `directory`
 110         Directory the CSV files reside in.  Defaults to the `pokedex` data
 111         directory.
 112
 113     `drop_tables`
 114         If set to True, existing `pokedex`-related tables will be dropped.
 115
 116     `verbose`
 117         If set to True, status messages will be printed to stdout.
 118
 119     `safe`
 120         If set to False, load can be faster, but can corrupt the database if
 121         it crashes or is interrupted.
 122     """
 123
 124     # First take care of verbosity
 125     print_start, print_status, print_done = _get_verbose_prints(verbose)
 126
 127
 128     if directory is None:
 129         directory = get_default_csv_dir()
 130
 131     table_names = _get_table_names(metadata, tables)
 132     table_objs = [metadata.tables[name] for name in table_names]
 133     table_objs = sqlalchemy.sql.util.sort_tables(table_objs)
 134
 135     # SQLite speed tweaks
 136     if not safe and session.connection().dialect.name == 'sqlite':
 137         session.connection().execute("PRAGMA synchronous=OFF")
 138         session.connection().execute("PRAGMA journal_mode=OFF")
 139
 140     # Drop all tables if requested
 141     if drop_tables:
 142         print_start('Dropping tables')
 143         for table in reversed(table_objs):
 144             table.drop(checkfirst=True)
 145         print_done()
 146
 147     for table in table_objs:
 148         table.create()
 149     connection = session.connection()
 150
 151     # Okay, run through the tables and actually load the data now
 152     for table_obj in table_objs:
 153         table_name = table_obj.name
 154         insert_stmt = table_obj.insert()
 155
 156         print_start(table_name)
 157
 158         try:
 159             csvpath = "%s/%s.csv" % (directory, table_name)
 160             csvfile = open(csvpath, 'rb')
 161         except IOError:
 162             # File doesn't exist; don't load anything!
 163             print_done('missing?')
 164             continue
 165
 166         csvsize = os.stat(csvpath).st_size
 167
 168         reader = csv.reader(csvfile, lineterminator='\n')
 169         column_names = [unicode(column) for column in reader.next()]
 170
 171         # Self-referential tables may contain rows with foreign keys of other
 172         # rows in the same table that do not yet exist.  Pull these out and add
 173         # them to the session last
 174         # ASSUMPTION: Self-referential tables have a single PK called "id"
 175         deferred_rows = []  # ( row referring to id, [foreign ids we need] )
 176         seen_ids = {}       # primary key we've seen => 1
 177
 178         # Fetch foreign key columns that point at this table, if any
 179         self_ref_columns = []
 180         for column in table_obj.c:
 181             if any(_.references(table_obj) for _ in column.foreign_keys):
 182                 self_ref_columns.append(column)
 183
 184         new_rows = []
 185         def insert_and_commit():
 186             session.connection().execute(insert_stmt, new_rows)
 187             session.commit()
 188             new_rows[:] = []
 189
 190             progress = "%d%%" % (100 * csvfile.tell() // csvsize)
 191             print_status(progress)
 192
 193         for csvs in reader:
 194             row_data = {}
 195
 196             for column_name, value in zip(column_names, csvs):
 197                 column = table_obj.c[column_name]
 198                 if column.nullable and value == '':
 199                     # Empty string in a nullable column really means NULL
 200                     value = None
 201                 elif isinstance(column.type, sqlalchemy.types.Boolean):
 202                     # Boolean values are stored as string values 0/1, but both
 203                     # of those evaluate as true; SQLA wants True/False
 204                     if value == '0':
 205                         value = False
 206                     else:
 207                         value = True
 208                 else:
 209                     # Otherwise, unflatten from bytes
 210                     value = value.decode('utf-8')
 211
 212                 # nb: Dictionaries flattened with ** have to have string keys
 213                 row_data[ str(column_name) ] = value
 214
 215             # May need to stash this row and add it later if it refers to a
 216             # later row in this table
 217             if self_ref_columns:
 218                 foreign_ids = [row_data[_.name] for _ in self_ref_columns]
 219                 foreign_ids = [_ for _ in foreign_ids if _]  # remove NULL ids
 220
 221                 if not foreign_ids:
 222                     # NULL key.  Remember this row and add as usual.
 223                     seen_ids[row_data['id']] = 1
 224
 225                 elif all(_ in seen_ids for _ in foreign_ids):
 226                     # Non-NULL key we've already seen.  Remember it and commit
 227                     # so we know the old row exists when we add the new one
 228                     insert_and_commit()
 229                     seen_ids[row_data['id']] = 1
 230
 231                 else:
 232                     # Non-NULL future id.  Save this and insert it later!
 233                     deferred_rows.append((row_data, foreign_ids))
 234                     continue
 235
 236             # Insert row!
 237             new_rows.append(row_data)
 238
 239             # Remembering some zillion rows in the session consumes a lot of
 240             # RAM.  Let's not do that.  Commit every 1000 rows
 241             if len(new_rows) >= 1000:
 242                 insert_and_commit()
 243
 244         insert_and_commit()
 245
 246         # Attempt to add any spare rows we've collected
 247         for row_data, foreign_ids in deferred_rows:
 248             if not all(_ in seen_ids for _ in foreign_ids):
 249                 # Could happen if row A refers to B which refers to C.
 250                 # This is ridiculous and doesn't happen in my data so far
 251                 raise ValueError("Too many levels of self-reference!  "
 252                                  "Row was: " + str(row))
 253
 254             session.connection().execute(
 255                 insert_stmt.values(**row_data)
 256             )
 257             seen_ids[row_data['id']] = 1
 258         session.commit()
 259
 260         print_done()
 261
 262     # SQLite check
 263     if session.connection().dialect.name == 'sqlite':
 264         session.connection().execute("PRAGMA integrity_check")
 265
 266
 267
 268 def dump(session, tables=[], directory=None, verbose=False):
 269     """Dumps the contents of a database to a set of CSV files.  Probably not
 270     useful to anyone besides a developer.
 271
 272     `session`
 273         SQLAlchemy session to use.
 274
 275     `tables`
 276         List of tables to dump.  If omitted, all tables are dumped.
 277
 278     `directory`
 279         Directory the CSV files should be put in.  Defaults to the `pokedex`
 280         data directory.
 281
 282     `verbose`
 283         If set to True, status messages will be printed to stdout.
 284     """
 285
 286     # First take care of verbosity
 287     print_start, print_status, print_done = _get_verbose_prints(verbose)
 288
 289
 290     if not directory:
 291         directory = get_default_csv_dir()
 292
 293     table_names = _get_table_names(metadata, tables)
 294     table_names.sort()
 295
 296
 297     for table_name in table_names:
 298         print_start(table_name)
 299         table = metadata.tables[table_name]
 300
 301         writer = csv.writer(open("%s/%s.csv" % (directory, table_name), 'wb'),
 302                             lineterminator='\n')
 303         columns = [col.name for col in table.columns]
 304         writer.writerow(columns)
 305
 306         primary_key = table.primary_key
 307         for row in session.query(table).order_by(*primary_key).all():
 308             csvs = []
 309             for col in columns:
 310                 # Convert Pythony values to something more universal
 311                 val = getattr(row, col)
 312                 if val == None:
 313                     val = ''
 314                 elif val == True:
 315                     val = '1'
 316                 elif val == False:
 317                     val = '0'
 318                 else:
 319                     val = unicode(val).encode('utf-8')
 320
 321                 csvs.append(val)
 322
 323             writer.writerow(csvs)
 324
 325         print_done()