app/django/contrib/gis/db/backend/util.py
author Lennard de Rijk <ljvderijk@gmail.com>
Thu, 05 Feb 2009 22:15:38 +0000
changeset 1225 1d5c58e24fd3
parent 323 ff1a9aa48cfd
permissions -rw-r--r--
Org applications can now only be made by a user when a program allows it. To do this a new access_type has been added called apply. This ensures that users can only used the seeded version of create. Also the review_overview now has his own access type to ensure the separability of hosts for different sponsors in case of org app reviews. Note that the access checks for hosts are broken and only give access to developers at the moment. Patch by: Lennard de Rijk Reviewed by: to-be-reviewed

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)