google.appengine.ext.db.ListProperty

A property that stores a list of things.

Inherits From: Property, expected_type

google.appengine.ext.db.ListProperty(
    item_type, verbose_name=None, default=None, write_empty_list=None, **kwds
)

This is a parameterized property; the parameter must be a valid non-list data type, and all items must conform to this type.

item_type Type for the list items; must be one of the allowed property types.
verbose_name Optional verbose name.
write_empty_list Optional whether to write empty list properties or no property
default Optional default value; if omitted, an empty list is used.
**kwds Optional additional keyword arguments, passed to base class. Note that the only permissible value for required is True.

Child Classes

class data_type

Methods

datastore_type

View source

datastore_type()

Deprecated backwards-compatible accessor method for self.data_type.

default_value

View source

default_value()

Default value for list.

Because the property supplied to default is a static value, that value must be shallow copied to prevent all fields with default values from sharing the same instance.

Returns
Copy of the default value.

empty

View source

empty(
    value
)

Is list property empty.

[] is not an empty value.

Returns
True if value is None, else False.

get_updated_value_for_datastore

View source

get_updated_value_for_datastore(
    model_instance
)

Determine new value for auto-updated property.

Some properies (e.g. DateTimeProperty, UserProperty) optionally update their value on every put(). This call must return the new desired value for such properties. For all other properties, this call must return AUTO_UPDATE_UNCHANGED.

Args
model_instance Instance to get new value for.

Returns
Datastore representation of the new model value in a form that is appropriate for storing in the datastore, or AUTO_UPDATE_UNCHANGED.

get_value_for_datastore

View source

get_value_for_datastore(
    model_instance
)

Get value from property to send to datastore.

Returns
validated list appropriate to save in the datastore.

make_value_from_datastore

View source

make_value_from_datastore(
    value
)

Native representation of this property.

If this list is a list of datetime.date or datetime.time, we convert the list of datetime.datetime retrieved from the entity into datetime.date or datetime.time.

See base class method documentation for details.

make_value_from_datastore_index_value

View source

make_value_from_datastore_index_value(
    index_value
)

validate

View source

validate(
    value
)

Validate list.

Returns
A valid value.

Raises
BadValueError if property is not a list whose items are instances of the item_type given to the constructor.

validate_list_contents

View source

validate_list_contents(
    value
)

Validates that all items in the list are of the correct type.

Returns
The validated list.

Raises
BadValueError if the list has items are not instances of the item_type given to the constructor.

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