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documentation for NullableField

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Dzianis Sivets 2017-06-16 20:27:25 +03:00
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docs/field_types.md
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@ -22,6 +22,7 @@ Currently the following field types are supported:
| Enum8Field | Enum8 | Enum | See below | Enum8Field | Enum8 | Enum | See below
| Enum16Field | Enum16 | Enum | See below | Enum16Field | Enum16 | Enum | See below
| ArrayField | Array | list | See below | ArrayField | Array | list | See below
| NullableField | Nullable | See below | See below
DateTimeField and Time Zones DateTimeField and Time Zones
---------------------------- ----------------------------
@ -103,6 +104,30 @@ Usage:
# created_date and username will contain a default value # created_date and username will contain a default value
db.select('SELECT * FROM $db.event', model_class=Event) db.select('SELECT * FROM $db.event', model_class=Event)
Working with nullable fields
------------------------------------------
From [some time](https://github.com/yandex/ClickHouse/pull/70) ClickHouse provides a NULL value support.
Also see some information [here](https://github.com/yandex/ClickHouse/blob/master/dbms/tests/queries/0_stateless/00395_nullable.sql).
You can create fields, that can contain any data type (except Enum)
or 'None' value, for example:
class EventData(models.Model):
date = fields.DateField()
comment = fields.NullableField(fields.StringField(), extra_null_values={''})
score = fields.NullableField(fields.UInt8Field())
serie = fields.NullableField(fields.ArrayField(fields.UInt8Field()))
engine = engines.MergeTree('date', ('date',))
score_event = EventData(date=date.today(), comment=None, score=5, serie=None)
comment_event = EventData(date=date.today(), comment='Excellent!', score=None, serie=None)
another_event = EventData(date=date.today(), comment='', score=None, serie=None)
action_event = EventData(date=date.today(), comment='', score=None, serie=[1, 2, 3])
NOTE: ArrayField of NullableField yet not supported.
--- ---