• Language: en
  • 2.0
  • Documentation version: development

Source code for django.db.models.functions.window

from django.db.models import FloatField, Func, IntegerField

__all__ = [
    'CumeDist', 'DenseRank', 'FirstValue', 'Lag', 'LastValue', 'Lead',
    'NthValue', 'Ntile', 'PercentRank', 'Rank', 'RowNumber',
]


[docs]class CumeDist(Func): function = 'CUME_DIST' name = 'CumeDist' output_field = FloatField() window_compatible = True
[docs]class DenseRank(Func): function = 'DENSE_RANK' name = 'DenseRank' output_field = IntegerField() window_compatible = True
[docs]class FirstValue(Func): arity = 1 function = 'FIRST_VALUE' name = 'FirstValue' window_compatible = True
class LagLeadFunction(Func): window_compatible = True def __init__(self, expression, offset=1, default=None, **extra): if expression is None: raise ValueError( '%s requires a non-null source expression.' % self.__class__.__name__ ) if offset is None or offset <= 0: raise ValueError( '%s requires a positive integer for the offset.' % self.__class__.__name__ ) args = (expression, offset) if default is not None: args += (default,) super().__init__(*args, **extra) def _resolve_output_field(self): sources = self.get_source_expressions() return sources[0].output_field
[docs]class Lag(LagLeadFunction): function = 'LAG' name = 'Lag'
[docs]class LastValue(Func): arity = 1 function = 'LAST_VALUE' name = 'LastValue' window_compatible = True
[docs]class Lead(LagLeadFunction): function = 'LEAD' name = 'Lead'
[docs]class NthValue(Func): function = 'NTH_VALUE' name = 'NthValue' window_compatible = True def __init__(self, expression, nth=1, **extra): if expression is None: raise ValueError('%s requires a non-null source expression.' % self.__class__.__name__) if nth is None or nth <= 0: raise ValueError('%s requires a positive integer as for nth.' % self.__class__.__name__) super().__init__(expression, nth, **extra) def _resolve_output_field(self): sources = self.get_source_expressions() return sources[0].output_field
[docs]class Ntile(Func): function = 'NTILE' name = 'Ntile' output_field = IntegerField() window_compatible = True def __init__(self, num_buckets=1, **extra): if num_buckets <= 0: raise ValueError('num_buckets must be greater than 0.') super().__init__(num_buckets, **extra)
[docs]class PercentRank(Func): function = 'PERCENT_RANK' name = 'PercentRank' output_field = FloatField() window_compatible = True
[docs]class Rank(Func): function = 'RANK' name = 'Rank' output_field = IntegerField() window_compatible = True
[docs]class RowNumber(Func): function = 'ROW_NUMBER' name = 'RowNumber' output_field = IntegerField() window_compatible = True
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