Ticket #26327: expressions.py

File expressions.py, 1.5 KB (added by Tomasz Nowak, 9 years ago)
Line 
1from django.db.models import Expression
2
3__all__ = [
4 'JsonBuildObject',
5]
6
7
8class JsonBuildObject(Expression):
9 template = 'JSON_BUILD_OBJECT(%(expressions)s)'
10
11 def __init__(self, expressions, output_field, **extra):
12 super(JsonBuildObject, self).__init__(output_field=output_field)
13 for expression in expressions:
14 if not hasattr(expression, 'resolve_expression'):
15 raise TypeError('%r is not an Expression' % expression)
16 self.expressions = expressions
17 self.extra = extra
18
19 def resolve_expression(self, query=None, allow_joins=True, reuse=None, summarize=False, for_save=False):
20 c = self.copy()
21 c.is_summary = summarize
22 for pos, expression in enumerate(self.expressions):
23 c.expressions[pos] = expression.resolve_expression(query, allow_joins, reuse, summarize)
24 return c
25
26 def as_sql(self, compiler, connection):
27 sql_expressions, sql_params = [], []
28 for expression in self.expressions:
29 sql, params = compiler.compile(expression)
30 # "By convention, the argument list consists of alternating keys and values"
31 sql_expressions.append("'%s'" % expression.target.column)
32 sql_expressions.append(sql)
33 sql_params.extend(params)
34 self.extra['expressions'] = ','.join(sql_expressions)
35 return self.template % self.extra, sql_params
36
37 def get_source_expressions(self):
38 return self.expressions
39
40 def set_source_expressions(self, expressions):
41 self.expressions = expressions
42
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