wpylib/db/tables.py

# $Id: tables.py,v 1.1 2011-10-06 19:14:47 wirawan Exp $
#
# wpylib.db.tables module
# Created: 20100223
# Wirawan Purwanto
#

"""Simple table accessors for sqlite database."""

import sys
import os
import os.path
import time

try:
  import sqlite3
except:
  # For Python < 2.5:
  import pysqlite2.dbapi2 as sqlite3


# dtype map from python types to sqlite3 types:
dtype_map = {
  str: 'TEXT',
  int: 'INTEGER',
  float: 'REAL',
}

#
simple_row_type = None # returns tuple
indexable_row_type = sqlite3.Row


class simple_table(object):
  """Simple table with no primary key."""
  dtypes_default = []
  def __init__(self, src_name, table_name, dtypes=None):
    self.src_name = src_name
    self.table_name = table_name
    if isinstance(src_name, basestring): # os.path.isfile(src_name):
      self.db = sqlite3.connect(src_name)
      self.dbc = self.db.cursor()
    elif isinstance(src_name, sqlite3.Connection):
      self.src_name = None
      self.db = src_name
      self.dbc = self.db.cursor()
    else:
      raise ValueError, "Invalid src_name data type"
    self.db.text_factory = str
    self.sql_params = {
        'table_name': table_name,
    }
    self.debug = 1

    create_sql = """\
      CREATE TABLE IF NOT EXISTS '%(table_name)s' (
        """ \
        + ", ".join(["'%s' %s" % (dname, self.sqlite_dtype_map[dtyp])
                     for (dname,dtyp) in self.dtypes_default + list(dtypes)
                  ]) \
        + """
      );
      """
    self.exec_sql(create_sql)
    self.db.commit()

  def exec_sql(self, stmt, params=None):
    sql_stmt = stmt % self.sql_params
    if params:
      if self.debug:
        print "--SQL::", sql_stmt.rstrip()
        print "--val::", params
      return self.dbc.execute(sql_stmt, params)
    else:
      if self.debug:
        print "--SQL::", sql_stmt.rstrip()
      return self.dbc.execute(sql_stmt)

  def add_fields(self, dtypes):
    """Adds columns to the table."""
    for (dname, dtyp) in dtypes:
      self.exec_sql("ALTER TABLE '%(table_name)s' ADD COLUMN" \
                    + " '%s' %s;" % (dname, self.sqlite_dtype_map[dtyp])
                   )
    self.db.commit()

  def register_file(self, filename, replace=False, extra_values=None):
    """Register a file, note its mtime, and size, and digests its content."""
    filestats = get_file_stats(filename)
    fields = [
      ('md5sum', filestats['md5sum']),
      ('date', filestats['mdate']),
      ('time', filestats['mtime']),
      ('size', filestats['size']),
    ] + [
      kwpair for kwpair in extra_values
    ]
    dnames = [ dname for (dname,dval) in fields ]
    dvals = [ dval for (dname,dval) in fields ]

    if replace:
      # Test if we want to replace or to add.
      count = [
        x for x in self.exec_sql(
          "SELECT count(*) from '%(table_name)s' where filename = ?;",
          (filename,)
        )
      ][0][0]
      if count == 0: replace = False

    if replace:
      # WARNING: This will replace all the occurences of the entry with
      # the same filename.
      # Replaceable insert is not intended for tables with duplicate entries
      # of the same filename.
      insert_sql = "UPDATE '%(table_name)s' SET " \
        + ', '.join(["'%s' = ?" % d for d in dnames]) \
        + " WHERE filename = ?;"
      vals = tuple(dvals + [filename])
    else:
      insert_sql = "INSERT INTO '%(table_name)s' (filename, " \
        + ", ".join(["'%s'" % d for d in dnames]) \
        + ") VALUES (?" + ',?'*(len(fields)) + ");"
      vals = tuple([filename] + dvals)
    self.exec_sql(insert_sql, vals)

  def flush(self):
    self.db.commit()

  def get_filenames(self):
    """Reads all the file names in the table to memory."""
    return [
      rslt[0] for rslt in
        self.exec_sql("SELECT filename FROM '%(table_name)s' ORDER BY filename;")
    ]

  def __getitem__(self, **criteria):
    # Criteria could be SQL stmt
    """Reads all the entries matching in the `filename' field."""
    if filename.find("%") >= 0:
      sql_stmt = "SELECT * FROM '%(table_name)s' WHERE filename LIKE ?;"
    else:
      sql_stmt = "SELECT * FROM '%(table_name)s' WHERE filename = ?;"
    return [ rslt for rslt in self.exec_sql(sql_stmt, (filename,)) ]

  def __setitem__(self, filename, newdata):
    """Updates the metadata on the filename. Any other field than the filename
    can be updated. The filename serves as a unique key here.
    The newdata can be a hash, like this:

       A_file_table[filename] = {'date': 20041201, 'time': 122144}

    or a list of tuples:

       A_file_table[filename] = [('date': 20041201), ('time': 122144)]
    """
    if isinstance(newdata, dict) or "keys" in dir(newdata):
      dnames = newdata.keys()
      dvals = [ newdata[k] for k in dnames ]
    else:
      # Assuming an iterable with ('field', 'value') tuples.
      dnames = [ dname for (dname,dval) in newdata ]
      dvals = [ dval for (dname,dval) in newdata ]
    update_sql = "UPDATE '%(table_name)s' SET " \
      + ', '.join(["'%s' = ?" % d for d in dnames]) \
      + " WHERE filename = ?;"
    vals = tuple(dvals + [filename])
    self.exec_sql(update_sql, vals)

  def __contains__(self, filename):
    """Counts the number of record entries matching in the `filename' field."""
    if filename.find("%") >= 0:
      sql_stmt = "SELECT count(*) FROM '%(table_name)s' WHERE filename LIKE ?;"
    else:
      sql_stmt = "SELECT count(*) FROM '%(table_name)s' WHERE filename = ?;"
    return [ rslt for rslt in self.exec_sql(sql_stmt, (filename,)) ][0][0]

  count = __contains__

  def fields(self):
    """Returns the field names of the table of the latest query."""
    return [ z[0] for z in self.dbc.description ]

  def row_kind(self, kind=None):
    if kind:
      self.db.row_factory = kind
      # We will reload the cursor to account for the new factory
      self.dbc = self.db.cursor()
    return self.db.row_factory