app/django/contrib/gis/db/backend/util.py
author Sverre Rabbelier <srabbelier@gmail.com>
Sat, 12 Sep 2009 00:36:49 +0200
changeset 2898 ac5f77cd6046
parent 323 ff1a9aa48cfd
permissions -rw-r--r--
Fix 500 when saving /site/edit without email When saving /site/edit with no no_reply_email set, a 500 error page would be returned due to an empty value being passed as value to the datastore (which is not allowed for email fields).

from types import UnicodeType

def gqn(val):
    """
    The geographic quote name function; used for quoting tables and 
    geometries (they use single rather than the double quotes of the
    backend quotename function).
    """
    if isinstance(val, basestring):
        if isinstance(val, UnicodeType): val = val.encode('ascii')
        return "'%s'" % val
    else:
        return str(val)

class SpatialOperation(object):
    """
    Base class for generating spatial SQL.
    """
    def __init__(self, function='', operator='', result='', beg_subst='', end_subst=''):
        self.function = function
        self.operator = operator
        self.result = result
        self.beg_subst = beg_subst
        try:
            # Try and put the operator and result into to the
            # end substitution.
            self.end_subst = end_subst % (operator, result)
        except TypeError:
            self.end_subst = end_subst

    @property
    def sql_subst(self):
        return ''.join([self.beg_subst, self.end_subst])

    def as_sql(self, geo_col):
        return self.sql_subst % self.params(geo_col)

    def params(self, geo_col):
        return (geo_col, self.operator)

class SpatialFunction(SpatialOperation):
    """
    Base class for generating spatial SQL related to a function.
    """
    def __init__(self, func, beg_subst='%s(%s, %%s', end_subst=')', result='', operator=''):
        # Getting the function prefix.
        kwargs = {'function' : func, 'operator' : operator, 'result' : result,
                  'beg_subst' : beg_subst, 'end_subst' : end_subst,}
        super(SpatialFunction, self).__init__(**kwargs)

    def params(self, geo_col):
        return (self.function, geo_col)