SelectMultiple

This class represents a multiple-selection form widget that allows users to select one or more options from a list. It extends the standard selection functionality by enabling multiple selections and providing specialized logic to retrieve a list of values from submitted data. The class also ensures that the field is not considered omitted from data submissions, even when no options are selected.

Attributes

Attribute	Type	Description
allow_multiple_selected	boolean = True	A boolean flag that enables the selection of multiple options within the HTML select widget.

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Methods

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value_from_datadict()

@classmethod
def value_from_datadict(
    data: dict,
    files: dict,
    name: string
) - > list

Extracts the list of selected values for this widget from the provided data dictionary.

Parameters

Name	Type	Description
data	dict	A dictionary-like object containing the submitted form data, typically request.POST or request.GET.
files	dict	A dictionary-like object containing uploaded file data.
name	string	The name of the form field used as the key to look up values in the data dictionary.

Returns

Type	Description
list	A list of selected values associated with the widget name, or None if the name is not present.

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value_omitted_from_data()

@classmethod
def value_omitted_from_data(
    data: dict,
    files: dict,
    name: string
) - > boolean

Determines if the value for this widget is missing from the submitted data.

Parameters

Name	Type	Description
data	dict	A dictionary-like object containing the submitted form data.
files	dict	A dictionary-like object containing uploaded file data.
name	string	The name of the form field to check for presence in the data.

Returns

Type	Description
boolean	Always returns False because an unselected multiple select element does not appear in POST data, making it impossible to distinguish between an empty selection and an omitted field.

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