djblets.db.fields.modification_timestamp_field¶

Field for managing modification timestamps for a model.

class ModificationState[source]¶

Bases: object

Modification state for a tracked value.

modified¶

Whether or not the value has been manually modified.

Type:: bool

__init__()[source]¶: Initialize the state.

static get_attr_name(field_name)[source]¶

Return the attribute name for the state for the named field.

Parameters:: field_name (unicode) – The attribute name of the ModificationTimestampField.
Returns:: The name of the modification state attribute.
Return type:: unicode

class ModificationTrackedValue(field_name, state_name)[source]¶

Bases: object

A descriptor for tracking the modification of a value.

field_name¶

The attribute name of the field on the model.

Type:: unicode

state_name¶

The attribute name of the state on the model.

Type:: unicode

__init__(field_name, state_name)[source]¶

Initialize the descriptor.

Parameters:

field_name (unicode) – The name of the field attribute.
state_name (unicode) – The name of the state attribute.

__get__(instance, objtype=None)[source]¶

Return the value.

Parameters:

instance (django.db.models.Model) – The model instance.
objtype (type, optional) – The model class.

Returns:

The value.

Return type:

datetime.datetime

__set__(instance, value)[source]¶

Set the value.

This tracks modifications and sets the modified state if this is not the first call to this method (which occurs during object initialization).

Parameters:

instance (django.db.models.Model) – The instance to set the the value on.
value (datetime.datetime) – The value to set.

class ModificationTimestampField(*args, **kwargs)[source]¶

Bases: DateTimeField

A timestamp field that only updates existing objects or when None.

This is a subclass of DateTimeField that only auto-updates the timestamp when updating an existing object or when the value of the field is None. It’s similar to using auto_now=True, but custom timestamp values on new instances will not be replaced.

__init__(*args, **kwargs)[source]¶

Initialize the field.

Parameters:

*args (tuple) – Positional arguments for the field.
**kwargs (dict) – Additional keyword arguments for the field.

contribute_to_class(cls, name)[source]¶

Contribute the field attributes to the class.

Parameters:

cls (type) – The model class to contribute the field to.
name (unicode) – The name of the field.

pre_save(model_instance, add)[source]¶

Return the value of the field just before saving.

Parameters:

model_instance (django.db.models.Model) – The model instance being saved.
add (bool) – Whether this is being saved to the database for the first time.

Returns:

The date/time value being saved.

Return type:

datetime.datetime

__annotations__ = {}¶