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aaronmk
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# Database access
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import random
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import re
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import sys
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import ex_util
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class NameException(Exception): pass
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class DuplicateKeyException(Exception): pass
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def check_name(name):
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if re.search(r'\W', name) != None: raise NameException('Name "'+name
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+'" may contain only alphanumeric characters and _')
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def run_query(db, query, params=None):
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cur = db.cursor()
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try: cur.execute(query, params)
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except Exception, ex:
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ex_util.add_msg(ex, 'query: '+cur.query)
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raise
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return cur
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def row(cur): return cur.fetchone()
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def value(cur): return row(cur)[0]
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def with_savepoint(db, func):
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savepoint = 'savepoint_'+str(random.randint(0, sys.maxint)) # must be unique
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run_query(db, 'SAVEPOINT '+savepoint)
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try: return_val = func()
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except:
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run_query(db, 'ROLLBACK TO SAVEPOINT '+savepoint)
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raise
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else:
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run_query(db, 'RELEASE SAVEPOINT '+savepoint)
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return return_val
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def select(db, table, fields, conds):
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for field in fields: check_name(field)
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for key in conds.keys(): check_name(key)
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def cond(entry):
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key, value = entry
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cond_ = key+' '
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if value == None: cond_ += 'IS'
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else: cond_ += '='
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cond_ += ' %s'
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return cond_
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return run_query(db, 'SELECT '+', '.join(fields)+' FROM '+table+' WHERE '
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+' AND '.join(map(cond, conds.iteritems())), conds.values())
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def insert(db, table, row, get_id=False):
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check_name(table)
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keys = row.keys()
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for key in keys: check_name(key)
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query = 'INSERT INTO '+table+' ('+', '.join(keys)+') VALUES ('\
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+', '.join(['%s']*len(keys))+')'
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if get_id: query += ' RETURNING lastval()'
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cur = run_query(db, query, row.values())
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if get_id: return value(cur)
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def insert_ignore(db, table, row, get_id=False):
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try: return with_savepoint(db, lambda: insert(db, table, row, get_id))
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except Exception, ex:
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match = re.search(r'duplicate key value violates unique constraint "'
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+table+'_(\w+)_index"', str(ex))
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if match: raise DuplicateKeyException(match.group(1))
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else: raise
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def insert_or_get(db, table, row, pkey):
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try: return insert_ignore(db, table, row, True)
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except DuplicateKeyException, ex:
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dup_key = str(ex)
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return value(select(db, table, [pkey], {dup_key: row[dup_key]}))
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