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sqltemplate.py
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sqltemplate.py
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import re
import sys
import tempita
_var_re = re.compile(r'\{\{(.*?)\}\}')
def sqlsub(tmpl, stacklevel=1, marker='%s', f_globals=None, **args):
"""Return (sql, params), with %s as the param marker
>>> sqlsub('users.username = {{username.lower()}}', username='bob')
('users.username = %s', ['bob'])
"""
if not args:
args = {}
frame = sys._getframe(stacklevel)
args = frame.f_locals
f_globals = frame.f_globals
if f_globals is None:
f_globals = {}
params = []
sql = []
last_end = 0
for match in _var_re.finditer(tmpl):
sql.append(tmpl[last_end:match.start()])
sql.append(marker)
params.append(eval(match.group(1), args, f_globals))
last_end = match.end()
sql.append(tmpl[last_end:])
return ''.join(sql), params
class sql(unicode):
def __sql__(self):
return self
class sqllist(list):
def __sqllist__(self):
return self
def inserts(values):
values = values.items()
l = sqllist()
l.append(sql('(%s) VALUES (' % (', '.join(key for key, value in values))))
first = True
for key, value in values:
if first:
first = False
else:
l.append(sql(', '))
l.append(value)
l.append(sql(')'))
return l
def updates(values):
values = values.items()
l = sqllist()
first = True
for key, value in values:
if first:
first = False
else:
l.append(sql(', '))
l.append(sql('%s=' % key))
l.append(value)
return l
class SQLTemplate(tempita.Template):
default_namespace = tempita.Template.default_namespace.copy()
default_namespace.update(dict(
sql=sql,
inserts=inserts,
updates=updates,
))
def _repr(self, value, pos):
if hasattr(value, '__sql__'):
return tempita.Template._repr(self, value.__sql__(), pos)
elif hasattr(value, '__sqllist__'):
return sqllist(self._repr(item, pos) for item in value.__sqllist__())
else:
return _SQLValue(value)
def substitute(self, *args, **kw):
result = super(SQLTemplate, self).substitute(*args, **kw)
return SQLExpression.from_sequence(result)
def _interpret(self, ns):
__traceback_hide__ = True
parts = []
defs = {}
self._interpret_codes(self._parsed, ns, out=parts, defs=defs)
if '__inherit__' in defs:
inherit = defs.pop('__inherit__')
else:
inherit = None
return parts, defs, inherit
class SQLExpression(object):
def __init__(self, sql_chunks, params):
self.sql_chunks = sql_chunks
self.params = params
def args(self, paramstyle='format'):
sql = [self.sql_chunks[0]]
if paramstyle in ['qmark', 'format', 'numeric']:
params = []
else:
params = {}
for index, (chunk, param) in enumerate(zip(self.sql_chunks[1:], self.params)):
if paramstyle in ('qmark', 'format'):
if paramstyle == 'qmark':
sql.append('?')
elif paramstyle == 'format':
sql.append('%s')
else:
sql.append(':%s' % index)
params.append(param)
else:
if paramstyle == 'named':
sql.append(':n%s' % index)
elif paramstyle == 'pyformat':
sql.append('%%(n%s)' % index)
params['n%s' % index] = param
sql.append(chunk)
return (''.join(sql), params)
@classmethod
def from_sequence(cls, seq):
chunks = ['']
params = []
for item in cls._flatten(seq):
if isinstance(item, _SQLValue):
params.append(item.value)
chunks.append('')
else:
chunks[-1] += unicode(item)
return cls(chunks, params)
@staticmethod
def _flatten(seq):
result = []
for item in seq:
if hasattr(item, '__sqllist__'):
result.extend(SQLExpression._flatten(item))
else:
result.append(item)
return result
def __repr__(self):
sql = [self.sql_chunks[0]]
for chunk, item in zip(self.sql_chunks[1:], self.params):
sql.append('{%r}' % item)
sql.append(chunk)
return '<sql %s>' % ''.join(sql)
class _SQLValue(object):
def __init__(self, value):
self.value = value
def __repr__(self):
return '<SQLValue %r>' % self.value
__test__ = {
'sqltemplate':
r"""
>>> SQLTemplate('SELECT * FROM {{"user" | sql}} WHERE id = {{10}}').substitute()
<sql SELECT * FROM user WHERE id = {10}>
>>> SQLTemplate('INSERT INTO test {{inserts(dict(a=1, b=2))}}').substitute()
<sql INSERT INTO test (a, b) VALUES ({1}, {2})>
>>> SQLTemplate('UPDATE test SET {{updates(dict(a=1, b=2))}}').substitute()
<sql UPDATE test SET a={1}, b={2}>
"""}
if __name__ == '__main__':
import doctest
doctest.testmod()