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

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

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


[docs]class CumeDist(Func): function = "CUME_DIST" output_field = FloatField() window_compatible = True
[docs]class DenseRank(Func): function = "DENSE_RANK" output_field = IntegerField() window_compatible = True
[docs]class FirstValue(Func): arity = 1 function = "FIRST_VALUE" 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"
[docs]class LastValue(Func): arity = 1 function = "LAST_VALUE" window_compatible = True
[docs]class Lead(LagLeadFunction): function = "LEAD"
[docs]class NthValue(Func): function = "NTH_VALUE" 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" 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" output_field = FloatField() window_compatible = True
[docs]class Rank(Func): function = "RANK" output_field = IntegerField() window_compatible = True
[docs]class RowNumber(Func): function = "ROW_NUMBER" output_field = IntegerField() window_compatible = True
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