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"""Help to generate SQL strings usable by the Python DB-API.
:author: Logilab
:copyright: 2000-2008 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
:license: General Public License version 2 - http://www.gnu.org/licenses
"""
__docformat__ = "restructuredtext en"
# SQLGenerator ################################################################
class SQLGenerator :
"""
Helper class to generate SQL strings to use with python's DB-API.
"""
def where(self, keys, addon=None) :
"""
:param keys: list of keys
>>> s = SQLGenerator()
>>> s.where(['nom'])
'nom = %(nom)s'
>>> s.where(['nom','prenom'])
'nom = %(nom)s AND prenom = %(prenom)s'
>>> s.where(['nom','prenom'], 'x.id = y.id')
'x.id = y.id AND nom = %(nom)s AND prenom = %(prenom)s'
"""
restriction = ["%s = %%(%s)s" % (x, x) for x in keys]
if addon:
restriction.insert(0, addon)
return " AND ".join(restriction)
def set(self, keys) :
"""
:param keys: list of keys
>>> s = SQLGenerator()
>>> s.set(['nom'])
'nom = %(nom)s'
>>> s.set(['nom','prenom'])
'nom = %(nom)s, prenom = %(prenom)s'
"""
return ", ".join(["%s = %%(%s)s" % (x, x) for x in keys])
def insert(self, table, params) :
"""
:param table: name of the table
:param params: dictionnary that will be used as in cursor.execute(sql,params)
>>> s = SQLGenerator()
>>> s.insert('test',{'nom':'dupont'})
'INSERT INTO test ( nom ) VALUES ( %(nom)s )'
>>> s.insert('test',{'nom':'dupont','prenom':'jean'})
'INSERT INTO test ( nom, prenom ) VALUES ( %(nom)s, %(prenom)s )'
"""
keys = ', '.join(params.keys())
values = ', '.join(["%%(%s)s" % x for x in params])
sql = 'INSERT INTO %s ( %s ) VALUES ( %s )' % (table, keys, values)
return sql
def select(self, table, params) :
"""
:param table: name of the table
:param params: dictionnary that will be used as in cursor.execute(sql,params)
>>> s = SQLGenerator()
>>> s.select('test',{})
'SELECT * FROM test'
>>> s.select('test',{'nom':'dupont'})
'SELECT * FROM test WHERE nom = %(nom)s'
>>> s.select('test',{'nom':'dupont','prenom':'jean'})
'SELECT * FROM test WHERE nom = %(nom)s AND prenom = %(prenom)s'
"""
sql = 'SELECT * FROM %s' % table
where = self.where(params.keys())
if where :
sql = sql + ' WHERE %s' % where
return sql
def adv_select(self, model, tables, params, joins=None) :
"""
:param model: list of columns to select
:param tables: list of tables used in from
:param params: dictionnary that will be used as in cursor.execute(sql, params)
:param joins: optional list of restriction statements to insert in the
where clause. Usually used to perform joins.
>>> s = SQLGenerator()
>>> s.adv_select(['column'],[('test', 't')], {})
'SELECT column FROM test AS t'
>>> s.adv_select(['column'],[('test', 't')], {'nom':'dupont'})
'SELECT column FROM test AS t WHERE nom = %(nom)s'
"""
table_names = ["%s AS %s" % (k, v) for k, v in tables]
sql = 'SELECT %s FROM %s' % (', '.join(model), ', '.join(table_names))
if joins and type(joins) != type(''):
joins = ' AND '.join(joins)
where = self.where(params.keys(), joins)
if where :
sql = sql + ' WHERE %s' % where
return sql
def delete(self, table, params) :
"""
:param table: name of the table
:param params: dictionnary that will be used as in cursor.execute(sql,params)
>>> s = SQLGenerator()
>>> s.delete('test',{'nom':'dupont'})
'DELETE FROM test WHERE nom = %(nom)s'
>>> s.delete('test',{'nom':'dupont','prenom':'jean'})
'DELETE FROM test WHERE nom = %(nom)s AND prenom = %(prenom)s'
"""
where = self.where(params.keys())
sql = 'DELETE FROM %s WHERE %s' % (table, where)
return sql
def update(self, table, params, unique) :
"""
:param table: name of the table
:param params: dictionnary that will be used as in cursor.execute(sql,params)
>>> s = SQLGenerator()
>>> s.update('test', {'id':'001','nom':'dupont'}, ['id'])
'UPDATE test SET nom = %(nom)s WHERE id = %(id)s'
>>> s.update('test',{'id':'001','nom':'dupont','prenom':'jean'},['id'])
'UPDATE test SET nom = %(nom)s, prenom = %(prenom)s WHERE id = %(id)s'
"""
where = self.where(unique)
set = self.set([key for key in params if key not in unique])
sql = 'UPDATE %s SET %s WHERE %s' % (table, set, where)
return sql
class BaseTable:
"""
Another helper class to ease SQL table manipulation.
"""
# table_name = "default"
# supported types are s/i/d
# table_fields = ( ('first_field','s'), )
# primary_key = 'first_field'
def __init__(self, table_name, table_fields, primary_key=None):
if primary_key is None:
self._primary_key = table_fields[0][0]
else:
self._primary_key = primary_key
self._table_fields = table_fields
self._table_name = table_name
info = {
'key' : self._primary_key,
'table' : self._table_name,
'columns' : ",".join( [ f for f,t in self._table_fields ] ),
'values' : ",".join( [sql_repr(t, "%%(%s)s" % f)
for f,t in self._table_fields] ),
'updates' : ",".join( ["%s=%s" % (f, sql_repr(t, "%%(%s)s" % f))
for f,t in self._table_fields] ),
}
self._insert_stmt = ("INSERT into %(table)s (%(columns)s) "
"VALUES (%(values)s) WHERE %(key)s=%%(key)s") % info
self._update_stmt = ("UPDATE %(table)s SET (%(updates)s) "
"VALUES WHERE %(key)s=%%(key)s") % info
self._select_stmt = ("SELECT %(columns)s FROM %(table)s "
"WHERE %(key)s=%%(key)s") % info
self._delete_stmt = ("DELETE FROM %(table)s "
"WHERE %(key)s=%%(key)s") % info
for k, t in table_fields:
if hasattr(self, k):
raise ValueError("Cannot use %s as a table field" % k)
setattr(self, k,None)
def as_dict(self):
d = {}
for k, t in self._table_fields:
d[k] = getattr(self, k)
return d
def select(self, cursor):
d = { 'key' : getattr(self,self._primary_key) }
cursor.execute(self._select_stmt % d)
rows = cursor.fetchall()
if len(rows)!=1:
msg = "Select: ambiguous query returned %d rows"
raise ValueError(msg % len(rows))
for (f, t), v in zip(self._table_fields, rows[0]):
setattr(self, f, v)
def update(self, cursor):
d = self.as_dict()
cursor.execute(self._update_stmt % d)
def delete(self, cursor):
d = { 'key' : getattr(self,self._primary_key) }
# Helper functions #############################################################
def name_fields(cursor, records) :
"""
Take a cursor and a list of records fetched with that cursor, then return a
list of dictionnaries (one for each record) whose keys are column names and
values are records' values.
:param cursor: cursor used to execute the query
:param records: list returned by fetch*()
"""
result = []
for record in records :
record_dict = {}
for i in range(len(record)) :
record_dict[cursor.description[i][0]] = record[i]
result.append(record_dict)
return result
def sql_repr(type, val):
if type == 's':
return "'%s'" % (val,)
else:
return val
if __name__ == "__main__":
import doctest
from logilab.common import sqlgen
print doctest.testmod(sqlgen)
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