email.utils: Miscellaneous utilities

Código fuente: Lib/email/utils.py

There are a couple of useful utilities provided in the email.utils module:

email.utils.localtime(dt=None)

Return local time as an aware datetime object. If called without arguments, return the current time. Otherwise the dt argument should be a datetime instance, and it is converted to the local time zone according to the system time zone database. If dt is naive (that is, dt.tzinfo is None), it is assumed to be in local time.

Added in version 3.3.

Deprecated since version 3.12, removed in version 3.14: El parámetro isdst.

email.utils.make_msgid(idstring=None, domain=None)

Returns a string suitable for an RFC 2822-compliant Message-ID header. Optional idstring, if given, is a string used to strengthen the uniqueness of the message id. Optional domain, if given, provides the portion of the msgid after the “@”. The default is the local hostname. It is normally not necessary to override this default, but may be useful in certain cases, such as constructing a distributed system that uses a consistent domain name across multiple hosts.

Distinto en la versión 3.2: Se añadió la palabra clave domain.

Las funciones que quedan son parte de la API de correo electrónico heredada (Compat32) . No hay necesidad de utilizarlas directamente con el nuevo API, dado que el análisis sintáctico y formateo que proporcionan es realizado automáticamente por el mecanismo de análisis sintáctico de la nueva API.

email.utils.quote(str)

Retorna una nueva cadena de caracteres con barras invertidas (\) en str reemplazado por dos barras invertidas, y comillas dobles reemplazadas por barra invertida seguido de comillas dobles.

email.utils.unquote(str)

Retorna una nueva cadena de caracteres que es una versión unquoted de str. Si str comienza y termina con comillas dobles, éstas son eliminadas. De igual manera si str empieza y termina con comillas angulares (< y >), éstas son eliminadas.

email.utils.parseaddr(address, *, strict=True)

Interpreta address – la cual debe ser el valor de un campo que contenga un campo tal como To o Cc – para separarlo en sus componentes realname y email address. Retorna una tupla de información, a menos que la interpretación falle, en cuyo caso una 2-tupla de ('','') es retornada.

If strict is true, use a strict parser which rejects malformed inputs.

Distinto en la versión 3.13: Add strict optional parameter and reject malformed inputs by default.

email.utils.formataddr(pair, charset='utf-8')

The inverse of parseaddr(), this takes a 2-tuple of the form (realname, email_address) and returns the string value suitable for a To or Cc header. If the first element of pair is false, then the second element is returned unmodified.

El charset opcional es el conjunto de caracteres que será usado en la codificación RFC 2047 del real_name si el real_name contiene caracteres que no sean ASCII. Puede ser una instancia de str o Charset. El valor predeterminado es utf-8.

Distinto en la versión 3.3: Se añadió la opción charset.

email.utils.getaddresses(fieldvalues, *, strict=True)

This function returns a list of 2-tuples of the form returned by parseaddr(). fieldvalues is a sequence of header field values as might be returned by Message.get_all().

If strict is true, use a strict parser which rejects malformed inputs.

Here’s a simple example that gets all the recipients of a message:

from email.utils import getaddresses

tos = msg.get_all('to', [])
ccs = msg.get_all('cc', [])
resent_tos = msg.get_all('resent-to', [])
resent_ccs = msg.get_all('resent-cc', [])
all_recipients = getaddresses(tos + ccs + resent_tos + resent_ccs)

Distinto en la versión 3.13: Add strict optional parameter and reject malformed inputs by default.

email.utils.parsedate(date)

Attempts to parse a date according to the rules in RFC 2822 Section 3.3. However, some mailers don’t follow that format as specified, so parsedate() tries to guess correctly in such cases. date is a string containing an RFC 2822 date, such as "Mon, 20 Nov 1995 19:12:08 -0500". If it succeeds in parsing the date, parsedate() returns a 9-tuple that can be passed directly to time.mktime(); otherwise None will be returned. Note that indexes 6, 7, and 8 of the result tuple are not usable.

email.utils.parsedate_tz(date)

Realiza la misma función que parsedate(), pero retorna None o una 10-tupla; los primeros 9 elementos forman una tupla que puede ser pasada directamente a time.mktime(), y el décimo es el desfase de la zona horaria de la fecha con respecto a UTC (que es el término oficial para Greenwich Mean Time) [1]. Si la cadena de caracteres de entrada no tiene zona horaria, el último elemento de la tupla retornada es 0, el cual representa UTC. Nótese que los índices 6, 7 y 8 de la tupla resultante no son utilizables.

email.utils.parsedate_to_datetime(date)

The inverse of format_datetime(). Performs the same function as parsedate(), but on success returns a datetime; otherwise ValueError is raised if date contains an invalid value such as an hour greater than 23 or a timezone offset not between -24 and 24 hours. If the input date has a timezone of -0000, the datetime will be a naive datetime, and if the date conforms to the RFCs it will represent a time in UTC but with no indication of the actual source timezone of the message the date comes from. If the input date has any other valid timezone offset, the datetime will be an aware datetime whose corresponding tzinfo attribute is a timezone object.

Added in version 3.3.

email.utils.mktime_tz(tuple)

Cambia una 10-tupla, como la retornada por parsedate_tz() a una marca de tiempo UTC (segundos desde la Época). Si la zona horaria en la tupla es None, asume el tiempo local.

email.utils.formatdate(timeval=None, localtime=False, usegmt=False)

Returns a date string as per RFC 2822, for example:

Fri, 09 Nov 2001 01:08:47 -0000

Optional timeval, if given, is a floating-point time value as accepted by time.gmtime() and time.localtime(), otherwise the current time is used.

Optional localtime is a flag that when True, interprets timeval, and returns a date relative to the local timezone instead of UTC, properly taking daylight saving time into account. The default is False meaning UTC is used.

Optional usegmt is a flag that when True, outputs a date string with the timezone as an ASCII string GMT, rather than a numeric -0000. This is needed for some protocols (such as HTTP). This only applies when localtime is False. The default is False.

email.utils.format_datetime(dt, usegmt=False)

Like formatdate(), but the input is a datetime instance. If it is a naive datetime, it is assumed to be «UTC with no information about the source timezone», and the conventional -0000 is used for the timezone. If it is an aware datetime, then the numeric timezone offset is used. If it is an aware timezone with offset zero, then usegmt may be set to True, in which case the string GMT is used instead of the numeric timezone offset. This provides a way to generate standards-conformant HTTP date headers.

Added in version 3.3.

email.utils.decode_rfc2231(s)

Decodifica la cadena de caracteres s de acuerdo a RFC 2231.

email.utils.encode_rfc2231(s, charset=None, language=None)

Encode the string s according to RFC 2231. Optional charset and language, if given, are the character set name and language name to use. If neither is given, s is returned as-is. If charset is given but language is not, the string is encoded using the empty string for language.

email.utils.collapse_rfc2231_value(value, errors='replace', fallback_charset='us-ascii')

When a header parameter is encoded in RFC 2231 format, Message.get_param() may return a 3-tuple containing the character set, language, and value. collapse_rfc2231_value() turns this into a string. Optional errors is passed to the errors argument of str’s encode() method; it defaults to 'replace'. Optional fallback_charset specifies the character set to use if the one in the RFC 2231 header is not known by Python; it defaults to 'us-ascii'.

Por conveniencia, si el value pasado a collapse_rfc2231_value() no es una tupla, debería ser una cadena de caracteres y se retorna sin citar.

email.utils.decode_params(params)

Decodifica la lista de parámetros de acuerdo a RFC 2231. params es una secuencia de 2-tuplas conteniendo elementos de la forma (content-type, string-value).

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