How to use the common.schema_fields.SchemaField function in common

'name', 'Name', 'string', description='user name'))
        sub_registry.add_property(schema_fields.SchemaField(
            'city', 'City', 'string', description='city name'))
        reg.add_sub_registry('sub_registry', title='Sub Registry',
                             description='a sub-registry',
                             registry=sub_registry)

        reg.add_property(schema_fields.FieldArray(
            'simple_array', 'Simple Array', description='a simple array',
            item_type=schema_fields.SchemaField(
                'array_int', 'Array Int', 'integer', description='array int')))

        complex_array_type = schema_fields.FieldRegistry('complex_array_type')
        complex_array_type.add_property(schema_fields.SchemaField(
            'this', 'This', 'string', description='the this'))
        complex_array_type.add_property(schema_fields.SchemaField(
            'that', 'That', 'number', description='the that'))
        complex_array_type.add_property(schema_fields.SchemaField(
            'these', 'These', 'datetime', description='the these'))
        reg.add_property(schema_fields.FieldArray(
            'complex_array', 'Complex Array', description='complex array',
            item_type=complex_array_type))
        actual_schema = self.job._json_schema_to_bigquery_schema(
            reg.get_json_schema_dict()['properties'])

        expected_schema = [
            {'mode': 'NULLABLE',
             'type': 'INTEGER',
             'name': 'an_integer',
             'description': 'an integer'},
            {'mode': 'REQUIRED',
             'type': 'STRING',

optional=True, description='an integer'))
        reg.add_property(schema_fields.SchemaField(
            'a_string', 'A String', 'string', description='a string'))
        reg.add_property(schema_fields.SchemaField(
            'some text', 'Some Text', 'text', description='some text'))
        reg.add_property(schema_fields.SchemaField(
            'some html', 'Some HTML', 'html', description='some html'))
        reg.add_property(schema_fields.SchemaField(
            'a url', 'A URL', 'url', description='a url'))
        reg.add_property(schema_fields.SchemaField(
            'a file', 'A File', 'file', description='a file'))
        reg.add_property(schema_fields.SchemaField(
            'a number', 'A Number', 'number', description='a number'))
        reg.add_property(schema_fields.SchemaField(
            'a boolean', 'A Boolean', 'boolean', description='a boolean'))
        reg.add_property(schema_fields.SchemaField(
            'a date', 'A Date', 'date', description='a date'))
        reg.add_property(schema_fields.SchemaField(
            'a datetime', 'A DateTime', 'datetime', description='a datetime'))

        sub_registry = schema_fields.FieldRegistry('subregistry')
        sub_registry.add_property(schema_fields.SchemaField(
            'name', 'Name', 'string', description='user name'))
        sub_registry.add_property(schema_fields.SchemaField(
            'city', 'City', 'string', description='city name'))
        reg.add_sub_registry('sub_registry', title='Sub Registry',
                             description='a sub-registry',
                             registry=sub_registry)

        reg.add_property(schema_fields.FieldArray(
            'simple_array', 'Simple Array', description='a simple array',
            item_type=schema_fields.SchemaField(

choice_type = schema_fields.SchemaField(
            'answer', 'Answer', 'string',
            description='An answer to the question')
        reg.add_property(schema_fields.FieldArray(
            'answers', 'Answers', item_type=choice_type,
            description='The answer from the student.  Note that '
            'this may be an array for questions permitting multiple answers.'))
        reg.add_property(schema_fields.SchemaField(
            'score', 'Score', 'number',
            description='Value from the Question indicating the score for '
            'this answer or set of answers.'))
        reg.add_property(schema_fields.SchemaField(
            'weighted_score', 'Weighted Score', 'number',
            description='Question score, multiplied by weights in '
            'containing Question Group, Assessment, etc.'))
        reg.add_property(schema_fields.SchemaField(
            'tallied', 'Tallied', 'boolean',
            description='Whether the score counts towards the overall grade.  '
            'Lessons by default do not contribute to course score, but may '
            'be marked as graded.'))
        return reg.get_json_schema_dict()['properties']

optional=True))

        opts.add_property(schema_fields.SchemaField(
            'course:blurb', 'Abstract', 'html',
            description=messages.HOMEPAGE_ABSTRACT_DESCRIPTION,
            extra_schema_dict_values={
                'supportCustomTags': common.tags.CAN_USE_DYNAMIC_TAGS.value,
                'excludedCustomTags':
                common.tags.EditorBlacklists.COURSE_SCOPE},
            optional=True))
        opts.add_property(schema_fields.SchemaField(
            'course:instructor_details', 'Instructor Details', 'html',
            description=messages.HOMEPAGE_INSTRUCTOR_DETAILS_DESCRIPTION,
            optional=True))

        opts.add_property(schema_fields.SchemaField(
            'course:main_image:url', 'Image or Video', 'string',
            description='URL for the preview image or YouTube video shown on '
            'the course homepage.', optional=True,
            extra_schema_dict_values={'_type': 'url', 'showMsg': True}))

        opts.add_property(schema_fields.SchemaField(
            'course:main_image:alt_text', 'Image Description', 'string',
            description='Alt text for the preview image on the course '
            'homepage.', optional=True))

        opts.add_property(schema_fields.SchemaField(
            'base:show_gplus_button', 'Show G+ Button', 'boolean',
            description=messages.HOMEPAGE_SHOW_GPLUS_BUTTON_DESCRIPTION,
            optional=True))

        opts.add_property(schema_fields.SchemaField(

def get_schema(cls, course, key):
        """Return the InputEx schema for the question group editor."""
        question_group = schema_fields.FieldRegistry(
            'Question Group', description='question_group')

        question_group.add_property(schema_fields.SchemaField(
            'version', '', 'string', optional=True, hidden=True))
        question_group.add_property(schema_fields.SchemaField(
            'description', 'Description', 'string', optional=True))
        question_group.add_property(schema_fields.SchemaField(
            'introduction', 'Introduction', 'html', optional=True))

        item_type = schema_fields.FieldRegistry(
            'Item',
            extra_schema_dict_values={'className': 'question-group-item'})
        item_type.add_property(schema_fields.SchemaField(
            'weight', 'Weight', 'number', optional=True, i18n=False,
            extra_schema_dict_values={'className': 'question-group-weight'}))

        question_select_data = [(q.id, q.description) for q in sorted(
            models.QuestionDAO.get_all(), key=lambda x: x.description)]

        item_type.add_property(schema_fields.SchemaField(
            'question', 'Question', 'string', optional=True, i18n=False,
            select_data=question_select_data,
            extra_schema_dict_values={'className': 'question-group-question'}))

        item_array_classes = 'question-group-items'
        if not question_select_data:
            item_array_classes += ' empty-question-list'

        item_array = schema_fields.FieldArray(

def schema_provider(unused_course):
    group = schema_fields.FieldRegistry(
        COURSE_EXPLORER_SETTINGS.label, extra_schema_dict_values={
            'className': 'inputEx-Group new-form-layout'})

    group.add_property(schema_fields.SchemaField(
        'title', 'Site Name', 'string',
        description=models_messages.SITE_NAME_DESCRIPTION,
        i18n=False,
        optional=True,
    ))

    group.add_property(schema_fields.SchemaField(
        'logo_url', 'Site Logo', 'string',
        description=messages.SITE_LOGO_DESCRIPTION,
        editable=False,
        extra_schema_dict_values={'visu': {
            'visuType': 'funcName',
            'funcName': 'renderImage',
        }},
        i18n=False,
        optional=True,

            lambda _: schema_fields.SchemaField(
                'course:' + constants.SHOW_IN_EXPLORER, 'Show in Explorer',
                'boolean',
                description=messages.COURSE_INCLUDE_IN_EXPLORER_DESCRIPTION,
                optional=True, i18n=False, default_value=True,
            ),

def get_schema(self, unused_handler):
        reg = schema_fields.FieldRegistry(OppiaTag.name())
        reg.add_property(
            schema_fields.SchemaField(
                'src', 'URL of the Oppia server', 'string', optional=False,
                description=(
                    'Provide the full URL of the Oppia server\'s domain, '
                    'e.g. \'https://www.oppia.org\'')))
        reg.add_property(
            schema_fields.SchemaField(
                'exploration_id', 'Exploration ID', 'string', optional=False,
                description=('The Oppia exploration id.')))
        return reg

def schema_provider(unused_course):
    group = schema_fields.FieldRegistry(
        COURSE_EXPLORER_SETTINGS.label, extra_schema_dict_values={
            'className': 'inputEx-Group new-form-layout'})

    group.add_property(schema_fields.SchemaField(
        'title', 'Site Name', 'string',
        description=models_messages.SITE_NAME_DESCRIPTION,
        i18n=False,
        optional=True,
    ))

    group.add_property(schema_fields.SchemaField(
        'logo_url', 'Site Logo', 'string',
        description=messages.SITE_LOGO_DESCRIPTION,
        editable=False,
        extra_schema_dict_values={'visu': {
            'visuType': 'funcName',
            'funcName': 'renderImage',
        }},
        i18n=False,
        optional=True,
    ))


    group.add_property(schema_fields.SchemaField(
        'logo', 'Change Site Logo', 'file',
        i18n=False,
        optional=True,

def generate_asset_rest_handler_schema(name, description, displayable=False):
    """Helper function for building schemas of asset-handling OEditor UIs."""

    schema = schema_fields.FieldRegistry('Asset', description='Asset')
    schema.add_property(schema_fields.SchemaField(
        'file', name, 'file', description=description))
    schema.add_property(schema_fields.SchemaField(
        'key', 'Key', 'string', editable=False, hidden=True))
    schema.add_property(schema_fields.SchemaField(
        'base', 'Base', 'string', editable=False, hidden=True))

    location_dict = {}
    if displayable:
        location_dict['visu'] = {
            'visuType': 'funcName',
            'funcName': 'renderAsset'}

    schema.add_property(schema_fields.SchemaField(
        'asset_url', 'Location', 'string', editable=False, optional=True,
        extra_schema_dict_values=location_dict))
    return schema