How to use the exchangelib.fields.CharField function in exchangelib

raise ValueError('Unsupported field %s' % field)
        if isinstance(field, URIField):
            return get_random_url()
        if isinstance(field, EmailAddressField):
            return get_random_email()
        if isinstance(field, ChoiceField):
            return get_random_choice(field.supported_choices(version=self.account.version))
        if isinstance(field, CultureField):
            return get_random_choice(['da-DK', 'de-DE', 'en-US', 'es-ES', 'fr-CA', 'nl-NL', 'ru-RU', 'sv-SE'])
        if isinstance(field, BodyField):
            return get_random_string(400)
        if isinstance(field, CharListField):
            return [get_random_string(16) for _ in range(random.randint(1, 4))]
        if isinstance(field, TextListField):
            return [get_random_string(400) for _ in range(random.randint(1, 4))]
        if isinstance(field, CharField):
            return get_random_string(field.max_length)
        if isinstance(field, TextField):
            return get_random_string(400)
        if isinstance(field, MimeContentField):
            return get_random_string(400)
        if isinstance(field, Base64Field):
            return get_random_bytes(400)
        if isinstance(field, BooleanField):
            return get_random_bool()
        if isinstance(field, DecimalField):
            return get_random_decimal(field.min or 1, field.max or 99)
        if isinstance(field, IntegerField):
            return get_random_int(field.min or 0, field.max or 256)
        if isinstance(field, DateTimeField):
            return get_random_datetime(tz=self.account.default_timezone)
        if isinstance(field, AttachmentField):

MessageHeaderField('headers', field_uri='item:InternetMessageHeaders', is_read_only=True),
        DateTimeField('datetime_sent', field_uri='item:DateTimeSent', is_read_only=True),
        DateTimeField('datetime_created', field_uri='item:DateTimeCreated', is_read_only=True),
        # Placeholder for ResponseObjects
        DateTimeField('reminder_due_by', field_uri='item:ReminderDueBy', is_required_after_save=True,
                      is_searchable=False),
        BooleanField('reminder_is_set', field_uri='item:ReminderIsSet', is_required=True, default=False),
        IntegerField('reminder_minutes_before_start', field_uri='item:ReminderMinutesBeforeStart',
                     is_required_after_save=True, min=0, default=0),
        CharField('display_cc', field_uri='item:DisplayCc', is_read_only=True),
        CharField('display_to', field_uri='item:DisplayTo', is_read_only=True),
        BooleanField('has_attachments', field_uri='item:HasAttachments', is_read_only=True),
        # ExtendedProperty fields go here
        CultureField('culture', field_uri='item:Culture', is_required_after_save=True, is_searchable=False),
        EffectiveRightsField('effective_rights', field_uri='item:EffectiveRights', is_read_only=True),
        CharField('last_modified_name', field_uri='item:LastModifiedName', is_read_only=True),
        DateTimeField('last_modified_time', field_uri='item:LastModifiedTime', is_read_only=True),
        BooleanField('is_associated', field_uri='item:IsAssociated', is_read_only=True, supported_from=EXCHANGE_2010),
        URIField('web_client_read_form_query_string', field_uri='item:WebClientReadFormQueryString',
                 is_read_only=True, supported_from=EXCHANGE_2010),
        URIField('web_client_edit_form_query_string', field_uri='item:WebClientEditFormQueryString',
                 is_read_only=True, supported_from=EXCHANGE_2010),
        EWSElementField('conversation_id', field_uri='item:ConversationId', value_cls=ConversationId,
                        is_read_only=True, supported_from=EXCHANGE_2010),
        BodyField('unique_body', field_uri='item:UniqueBody', is_read_only=True, supported_from=EXCHANGE_2010),
    ]

    FIELDS = LOCAL_FIELDS[0:1] + BaseItem.FIELDS + LOCAL_FIELDS[1:]

    __slots__ = tuple(f.name for f in LOCAL_FIELDS)

    # Used to register extended properties

def from_xml(self, elem, account):
        iter_elem = elem.find(self.response_tag())
        if iter_elem is not None:
            return get_xml_attrs(iter_elem, self.list_elem_tag())
        return self.default


class URIField(TextField):
    """Helper to mark strings that must conform to xsd:anyURI
    If we want an URI validator, see http://stackoverflow.com/questions/14466585/is-this-regex-correct-for-xsdanyuri
    """
    pass


class EmailAddressField(CharField):
    """A helper class used for email address string that we can use for email validation"""
    pass


class CultureField(CharField):
    """Helper to mark strings that are # RFC 1766 culture values."""
    pass


class Choice(object):
    """Implements versioned choices for the ChoiceField field"""
    def __init__(self, value, supported_from=None):
        self.value = value
        self.supported_from = supported_from

    def supports_version(self, version):

return value


class IdField(CharField):
    """A field to hold the 'Id' and 'Changekey' attributes on 'ItemId' type items. There is no guaranteed max length,
    but we can assume 512 bytes in practice. See
    https://docs.microsoft.com/en-us/exchange/client-developer/exchange-web-services/ews-identifiers-in-exchange
    """
    def __init__(self, *args, **kwargs):
        super(IdField, self).__init__(*args, **kwargs)
        self.max_length = 512  # This is above the normal 255 limit, but this is actually an attribute, not a field
        self.is_searchable = False
        self.is_attribute = True


class CharListField(CharField):
    is_list = True

    def list_elem_tag(self):
        return '{%s}String' % self.namespace

    def from_xml(self, elem, account):
        iter_elem = elem.find(self.response_tag())
        if iter_elem is not None:
            return get_xml_attrs(iter_elem, self.list_elem_tag())
        return self.default


class URIField(TextField):
    """Helper to mark strings that must conform to xsd:anyURI
    If we want an URI validator, see http://stackoverflow.com/questions/14466585/is-this-regex-correct-for-xsdanyuri
    """

"""
    ELEMENT_NAME = 'Message'
    LOCAL_FIELDS = [
        MailboxField('sender', field_uri='message:Sender', is_read_only=True, is_read_only_after_send=True),
        MailboxListField('to_recipients', field_uri='message:ToRecipients', is_read_only_after_send=True,
                         is_searchable=False),
        MailboxListField('cc_recipients', field_uri='message:CcRecipients', is_read_only_after_send=True,
                         is_searchable=False),
        MailboxListField('bcc_recipients', field_uri='message:BccRecipients', is_read_only_after_send=True,
                         is_searchable=False),
        BooleanField('is_read_receipt_requested', field_uri='message:IsReadReceiptRequested',
                     is_required=True, default=False, is_read_only_after_send=True),
        BooleanField('is_delivery_receipt_requested', field_uri='message:IsDeliveryReceiptRequested',
                     is_required=True, default=False, is_read_only_after_send=True),
        Base64Field('conversation_index', field_uri='message:ConversationIndex', is_read_only=True),
        CharField('conversation_topic', field_uri='message:ConversationTopic', is_read_only=True),
        # Rename 'From' to 'author'. We can't use fieldname 'from' since it's a Python keyword.
        MailboxField('author', field_uri='message:From', is_read_only_after_send=True),
        CharField('message_id', field_uri='message:InternetMessageId', is_read_only_after_send=True),
        BooleanField('is_read', field_uri='message:IsRead', is_required=True, default=False),
        BooleanField('is_response_requested', field_uri='message:IsResponseRequested', default=False, is_required=True),
        TextField('references', field_uri='message:References'),
        MailboxListField('reply_to', field_uri='message:ReplyTo', is_read_only_after_send=True, is_searchable=False),
        MailboxField('received_by', field_uri='message:ReceivedBy', is_read_only=True),
        MailboxField('received_representing', field_uri='message:ReceivedRepresenting', is_read_only=True),
        # Placeholder for ReminderMessageData
    ]
    FIELDS = Item.FIELDS + LOCAL_FIELDS

    __slots__ = tuple(f.name for f in LOCAL_FIELDS)

    def send(self, save_copy=True, copy_to_folder=None, conflict_resolution=AUTO_RESOLVE,

SOFT_DELETE = 'SoftDelete'
MOVE_TO_DELETED_ITEMS = 'MoveToDeletedItems'
DELETE_TYPE_CHOICES = (HARD_DELETE, SOFT_DELETE, MOVE_TO_DELETED_ITEMS)


class Item(BaseItem):
    """
    MSDN: https://docs.microsoft.com/en-us/exchange/client-developer/web-service-reference/item
    """
    ELEMENT_NAME = 'Item'

    LOCAL_FIELDS = [
        MimeContentField('mime_content', field_uri='item:MimeContent', is_read_only_after_send=True),
        EWSElementField('parent_folder_id', field_uri='item:ParentFolderId', value_cls=ParentFolderId,
                        is_read_only=True),
        CharField('item_class', field_uri='item:ItemClass', is_read_only=True),
        CharField('subject', field_uri='item:Subject'),
        ChoiceField('sensitivity', field_uri='item:Sensitivity', choices={
            Choice('Normal'), Choice('Personal'), Choice('Private'), Choice('Confidential')
        }, is_required=True, default='Normal'),
        TextField('text_body', field_uri='item:TextBody', is_read_only=True, supported_from=EXCHANGE_2013),
        BodyField('body', field_uri='item:Body'),  # Accepts and returns Body or HTMLBody instances
        AttachmentField('attachments', field_uri='item:Attachments'),  # ItemAttachment or FileAttachment
        DateTimeField('datetime_received', field_uri='item:DateTimeReceived', is_read_only=True),
        IntegerField('size', field_uri='item:Size', is_read_only=True),  # Item size in bytes
        CharListField('categories', field_uri='item:Categories'),
        ChoiceField('importance', field_uri='item:Importance', choices={
            Choice('Low'), Choice('Normal'), Choice('High')
        }, is_required=True, default='Normal'),
        TextField('in_reply_to', field_uri='item:InReplyTo'),
        BooleanField('is_submitted', field_uri='item:IsSubmitted', is_read_only=True),
        BooleanField('is_draft', field_uri='item:IsDraft', is_read_only=True),

choices={Choice(c) for c in ID_FORMATS}),
    ]

    __slots__ = tuple(f.name for f in FIELDS)


class AlternatePublicFolderItemId(EWSElement):
    """MSDN:
    https://docs.microsoft.com/en-us/exchange/client-developer/web-service-reference/alternatepublicfolderitemid
    """
    ELEMENT_NAME = 'AlternatePublicFolderItemId'
    FIELDS = [
        CharField('folder_id', field_uri='FolderId', is_required=True, is_attribute=True),
        ChoiceField('format', field_uri='Format', is_required=True, is_attribute=True,
                    choices={Choice(c) for c in ID_FORMATS}),
        CharField('item_id', field_uri='ItemId', is_required=True, is_attribute=True),
    ]

    __slots__ = tuple(f.name for f in FIELDS)


class IdChangeKeyMixIn(EWSElement):
    """Base class for classes that have 'id' and 'changekey' fields which are actually attributes on ID element"""
    ID_ELEMENT_CLS = ItemId

    FIELDS = [
        IdField('id', field_uri=ID_ELEMENT_CLS.ID_ATTR, is_read_only=True),
        IdField('changekey', field_uri=ID_ELEMENT_CLS.CHANGEKEY_ATTR, is_read_only=True),
    ]

    __slots__ = tuple(f.name for f in FIELDS)

super(CharField, self).__init__(*args, **kwargs)

    def clean(self, value, version=None):
        value = super(CharField, self).clean(value, version=version)
        if value is not None:
            if self.is_list:
                for v in value:
                    if len(v) > self.max_length:
                        raise ValueError("'%s' value '%s' exceeds length %s" % (self.name, v, self.max_length))
            else:
                if len(value) > self.max_length:
                    raise ValueError("'%s' value '%s' exceeds length %s" % (self.name, value, self.max_length))
        return value


class IdField(CharField):
    """A field to hold the 'Id' and 'Changekey' attributes on 'ItemId' type items. There is no guaranteed max length,
    but we can assume 512 bytes in practice. See
    https://docs.microsoft.com/en-us/exchange/client-developer/exchange-web-services/ews-identifiers-in-exchange
    """
    def __init__(self, *args, **kwargs):
        super(IdField, self).__init__(*args, **kwargs)
        self.max_length = 512  # This is above the normal 255 limit, but this is actually an attribute, not a field
        self.is_searchable = False
        self.is_attribute = True


class CharListField(CharField):
    is_list = True

    def list_elem_tag(self):
        return '{%s}String' % self.namespace

TextField('directory_id', field_uri='contacts:DirectoryId', supported_from=EXCHANGE_2013, is_read_only=True),
        # Placeholder for ManagerMailbox
        # Placeholder for DirectReports
    ]
    FIELDS = Item.FIELDS + LOCAL_FIELDS

    __slots__ = tuple(f.name for f in LOCAL_FIELDS)


class DistributionList(Item):
    """
    MSDN: https://docs.microsoft.com/en-us/exchange/client-developer/web-service-reference/distributionlist
    """
    ELEMENT_NAME = 'DistributionList'
    LOCAL_FIELDS = [
        CharField('display_name', field_uri='contacts:DisplayName', is_required=True),
        CharField('file_as', field_uri='contacts:FileAs', is_read_only=True),
        ChoiceField('contact_source', field_uri='contacts:ContactSource', choices={
            Choice('Store'), Choice('ActiveDirectory')
        }, is_read_only=True),
        MemberListField('members', field_uri='distributionlist:Members'),
    ]
    FIELDS = Item.FIELDS + LOCAL_FIELDS

    __slots__ = tuple(f.name for f in LOCAL_FIELDS)


class PostItem(Item):
    """
    MSDN: https://docs.microsoft.com/en-us/exchange/client-developer/web-service-reference/postitem
    """
    ELEMENT_NAME = 'PostItem'

}, default='None', is_required_after_save=True),
        TextField('profession', field_uri='contacts:Profession'),
        TextField('spouse_name', field_uri='contacts:SpouseName'),
        CharField('surname', field_uri='contacts:Surname'),
        DateTimeField('wedding_anniversary', field_uri='contacts:WeddingAnniversary'),
        BooleanField('has_picture', field_uri='contacts:HasPicture', supported_from=EXCHANGE_2010, is_read_only=True),
        TextField('phonetic_full_name', field_uri='contacts:PhoneticFullName', supported_from=EXCHANGE_2013,
                  is_read_only=True),
        TextField('phonetic_first_name', field_uri='contacts:PhoneticFirstName', supported_from=EXCHANGE_2013,
                  is_read_only=True),
        TextField('phonetic_last_name', field_uri='contacts:PhoneticLastName', supported_from=EXCHANGE_2013,
                  is_read_only=True),
        EmailAddressField('email_alias', field_uri='contacts:Alias', is_read_only=True),
        # 'notes' is documented in MSDN but apparently unused. Writing to it raises ErrorInvalidPropertyRequest. OWA
        # put entries into the 'notes' form field into the 'body' field.
        CharField('notes', field_uri='contacts:Notes', supported_from=EXCHANGE_2013, is_read_only=True),
        # 'photo' is documented in MSDN but apparently unused. Writing to it raises ErrorInvalidPropertyRequest. OWA
        # adds photos as FileAttachments on the contact item (with 'is_contact_photo=True'), which automatically flips
        # the 'has_picture' field.
        Base64Field('photo', field_uri='contacts:Photo', is_read_only=True),
        # Placeholder for UserSMIMECertificate
        # Placeholder for MSExchangeCertificate
        TextField('directory_id', field_uri='contacts:DirectoryId', supported_from=EXCHANGE_2013, is_read_only=True),
        # Placeholder for ManagerMailbox
        # Placeholder for DirectReports
    ]
    FIELDS = Item.FIELDS + LOCAL_FIELDS

    __slots__ = tuple(f.name for f in LOCAL_FIELDS)


class DistributionList(Item):