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