app/django/contrib/gis/db/backend/util.py
author Sverre Rabbelier <sverre@rabbelier.nl>
Mon, 07 Sep 2009 20:27:37 +0200
changeset 2878 cf4b80992451
parent 323 ff1a9aa48cfd
permissions -rw-r--r--
merge with wrong head
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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from types import UnicodeType
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def gqn(val):
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    """
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    The geographic quote name function; used for quoting tables and 
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    geometries (they use single rather than the double quotes of the
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    backend quotename function).
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    """
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    if isinstance(val, basestring):
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        if isinstance(val, UnicodeType): val = val.encode('ascii')
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        return "'%s'" % val
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    else:
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        return str(val)
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class SpatialOperation(object):
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    """
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    Base class for generating spatial SQL.
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    """
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    def __init__(self, function='', operator='', result='', beg_subst='', end_subst=''):
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        self.function = function
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        self.operator = operator
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        self.result = result
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        self.beg_subst = beg_subst
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        try:
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            # Try and put the operator and result into to the
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            # end substitution.
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            self.end_subst = end_subst % (operator, result)
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        except TypeError:
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            self.end_subst = end_subst
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    @property
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    def sql_subst(self):
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        return ''.join([self.beg_subst, self.end_subst])
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    def as_sql(self, geo_col):
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        return self.sql_subst % self.params(geo_col)
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    def params(self, geo_col):
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        return (geo_col, self.operator)
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class SpatialFunction(SpatialOperation):
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    """
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    Base class for generating spatial SQL related to a function.
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    """
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    def __init__(self, func, beg_subst='%s(%s, %%s', end_subst=')', result='', operator=''):
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        # Getting the function prefix.
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        kwargs = {'function' : func, 'operator' : operator, 'result' : result,
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                  'beg_subst' : beg_subst, 'end_subst' : end_subst,}
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        super(SpatialFunction, self).__init__(**kwargs)
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    def params(self, geo_col):
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        return (self.function, geo_col)