This widget allows you to display and edit only year or month/year in date fields.
Usage:
# model
class Model(models.Model):
json_field = fields.Json(string="Your JSON field")
# view
<form>;
....
<field name="date_year_field" widget="year_picker" />
....
<field name="date_month_field" widget="month_picker" />
....
</form>