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175 lines
4.7 KiB
Python
175 lines
4.7 KiB
Python
# copy_from.py -- example about copy_from
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#
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# Copyright (C) 2002 Tom Jenkins <tjenkins@devis.com>
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# Copyright (C) 2005 Federico Di Gregorio <fog@initd.org>
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#
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# psycopg2 is free software: you can redistribute it and/or modify it
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# under the terms of the GNU Lesser General Public License as published
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# by the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# psycopg2 is distributed in the hope that it will be useful, but WITHOUT
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# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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# License for more details.
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## put in DSN your DSN string
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DSN = 'dbname=test'
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## don't modify anything below this line (except for experimenting)
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import sys
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import os
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import StringIO
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import psycopg2
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if len(sys.argv) > 1:
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DSN = sys.argv[1]
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print("Opening connection using dsn:", DSN)
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conn = psycopg2.connect(DSN)
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print("Encoding for this connection is", conn.encoding)
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curs = conn.cursor()
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try:
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curs.execute("CREATE TABLE test_copy (fld1 text, fld2 text, fld3 int4)")
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except:
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conn.rollback()
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curs.execute("DROP TABLE test_copy")
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curs.execute("CREATE TABLE test_copy (fld1 text, fld2 text, fld3 int4)")
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conn.commit()
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# copy_from with default arguments, from open file
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io = open('copy_from.txt', 'wr')
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data = ['Tom\tJenkins\t37\n',
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'Madonna\t\\N\t45\n',
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'Federico\tDi Gregorio\t\\N\n']
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io.writelines(data)
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io.close()
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io = open('copy_from.txt', 'r')
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curs.copy_from(io, 'test_copy')
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print("1) Copy %d records from file object " % len(data) +
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"using defaults (sep: \\t and null = \\N)")
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io.close()
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curs.execute("SELECT * FROM test_copy")
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rows = curs.fetchall()
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print(" Select returned %d rows" % len(rows))
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for r in rows:
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print(" %s %s\t%s" % (r[0], r[1], r[2]))
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curs.execute("delete from test_copy")
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conn.commit()
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# copy_from using custom separator, from open file
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io = open('copy_from.txt', 'wr')
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data = ['Tom:Jenkins:37\n',
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'Madonna:\N:45\n',
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'Federico:Di Gregorio:\N\n']
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io.writelines(data)
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io.close()
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io = open('copy_from.txt', 'r')
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curs.copy_from(io, 'test_copy', ':')
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print("2) Copy %d records from file object using sep = :" % len(data))
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io.close()
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curs.execute("SELECT * FROM test_copy")
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rows = curs.fetchall()
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print(" Select returned %d rows" % len(rows))
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for r in rows:
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print(" %s %s\t%s" % (r[0], r[1], r[2]))
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curs.execute("delete from test_copy")
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conn.commit()
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# copy_from using custom null identifier, from open file
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io = open('copy_from.txt', 'wr')
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data = ['Tom\tJenkins\t37\n',
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'Madonna\tNULL\t45\n',
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'Federico\tDi Gregorio\tNULL\n']
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io.writelines(data)
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io.close()
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io = open('copy_from.txt', 'r')
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curs.copy_from(io, 'test_copy', null='NULL')
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print("3) Copy %d records from file object using null = NULL" % len(data))
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io.close()
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curs.execute("SELECT * FROM test_copy")
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rows = curs.fetchall()
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print(" Select using cursor returned %d rows" % len(rows))
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for r in rows:
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print(" %s %s\t%s" % (r[0], r[1], r[2]))
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curs.execute("delete from test_copy")
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conn.commit()
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# copy_from using custom separator and null identifier
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io = open('copy_from.txt', 'wr')
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data = ['Tom:Jenkins:37\n', 'Madonna:NULL:45\n', 'Federico:Di Gregorio:NULL\n']
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io.writelines(data)
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io.close()
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io = open('copy_from.txt', 'r')
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curs.copy_from(io, 'test_copy', ':', 'NULL')
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print("4) Copy %d records from file object " % len(data) +
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"using sep = : and null = NULL")
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io.close()
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curs.execute("SELECT * FROM test_copy")
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rows = curs.fetchall()
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print(" Select using cursor returned %d rows" % len(rows))
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for r in rows:
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print(" %s %s\t%s" % (r[0], r[1], r[2]))
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curs.execute("delete from test_copy")
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conn.commit()
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# anything can be used as a file if it has .read() and .readline() methods
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data = StringIO.StringIO()
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data.write('\n'.join(['Tom\tJenkins\t37',
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'Madonna\t\N\t45',
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'Federico\tDi Gregorio\t\N']))
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data.seek(0)
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curs.copy_from(data, 'test_copy')
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print("5) Copy 3 records from StringIO object using defaults")
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curs.execute("SELECT * FROM test_copy")
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rows = curs.fetchall()
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print(" Select using cursor returned %d rows" % len(rows))
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for r in rows:
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print(" %s %s\t%s" % (r[0], r[1], r[2]))
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curs.execute("delete from test_copy")
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conn.commit()
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# simple error test
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print("6) About to raise an error")
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data = StringIO.StringIO()
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data.write('\n'.join(['Tom\tJenkins\t37',
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'Madonna\t\N\t45',
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'Federico\tDi Gregorio\taaa']))
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data.seek(0)
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try:
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curs.copy_from(data, 'test_copy')
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except StandardError as err:
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conn.rollback()
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print(" Caught error (as expected):\n", err)
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conn.rollback()
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curs.execute("DROP TABLE test_copy")
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os.unlink('copy_from.txt')
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conn.commit()
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