Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1 | :mod:`email`: Parsing email messages |
| 2 | ------------------------------------ |
| 3 | |
| 4 | .. module:: email.parser |
| 5 | :synopsis: Parse flat text email messages to produce a message object structure. |
| 6 | |
| 7 | |
| 8 | Message object structures can be created in one of two ways: they can be created |
Georg Brandl | 3638e48 | 2009-04-27 16:46:17 +0000 | [diff] [blame] | 9 | from whole cloth by instantiating :class:`~email.message.Message` objects and |
| 10 | stringing them together via :meth:`attach` and :meth:`set_payload` calls, or they |
| 11 | can be created by parsing a flat text representation of the email message. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 12 | |
| 13 | The :mod:`email` package provides a standard parser that understands most email |
| 14 | document structures, including MIME documents. You can pass the parser a string |
Georg Brandl | 3638e48 | 2009-04-27 16:46:17 +0000 | [diff] [blame] | 15 | or a file object, and the parser will return to you the root |
| 16 | :class:`~email.message.Message` instance of the object structure. For simple, |
| 17 | non-MIME messages the payload of this root object will likely be a string |
| 18 | containing the text of the message. For MIME messages, the root object will |
| 19 | return ``True`` from its :meth:`is_multipart` method, and the subparts can be |
| 20 | accessed via the :meth:`get_payload` and :meth:`walk` methods. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 21 | |
| 22 | There are actually two parser interfaces available for use, the classic |
| 23 | :class:`Parser` API and the incremental :class:`FeedParser` API. The classic |
| 24 | :class:`Parser` API is fine if you have the entire text of the message in memory |
| 25 | as a string, or if the entire message lives in a file on the file system. |
| 26 | :class:`FeedParser` is more appropriate for when you're reading the message from |
| 27 | a stream which might block waiting for more input (e.g. reading an email message |
| 28 | from a socket). The :class:`FeedParser` can consume and parse the message |
| 29 | incrementally, and only returns the root object when you close the parser [#]_. |
| 30 | |
| 31 | Note that the parser can be extended in limited ways, and of course you can |
| 32 | implement your own parser completely from scratch. There is no magical |
| 33 | connection between the :mod:`email` package's bundled parser and the |
Georg Brandl | 3638e48 | 2009-04-27 16:46:17 +0000 | [diff] [blame] | 34 | :class:`~email.message.Message` class, so your custom parser can create message |
| 35 | object trees any way it finds necessary. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 36 | |
| 37 | |
| 38 | FeedParser API |
| 39 | ^^^^^^^^^^^^^^ |
| 40 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 41 | The :class:`FeedParser`, imported from the :mod:`email.feedparser` module, |
| 42 | provides an API that is conducive to incremental parsing of email messages, such |
| 43 | as would be necessary when reading the text of an email message from a source |
| 44 | that can block (e.g. a socket). The :class:`FeedParser` can of course be used |
| 45 | to parse an email message fully contained in a string or a file, but the classic |
| 46 | :class:`Parser` API may be more convenient for such use cases. The semantics |
| 47 | and results of the two parser APIs are identical. |
| 48 | |
| 49 | The :class:`FeedParser`'s API is simple; you create an instance, feed it a bunch |
| 50 | of text until there's no more to feed it, then close the parser to retrieve the |
| 51 | root message object. The :class:`FeedParser` is extremely accurate when parsing |
| 52 | standards-compliant messages, and it does a very good job of parsing |
| 53 | non-compliant messages, providing information about how a message was deemed |
| 54 | broken. It will populate a message object's *defects* attribute with a list of |
| 55 | any problems it found in a message. See the :mod:`email.errors` module for the |
| 56 | list of defects that it can find. |
| 57 | |
| 58 | Here is the API for the :class:`FeedParser`: |
| 59 | |
| 60 | |
R David Murray | 3edd22a | 2011-04-18 13:59:37 -0400 | [diff] [blame] | 61 | .. class:: FeedParser(_factory=email.message.Message, *, policy=policy.default) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 62 | |
| 63 | Create a :class:`FeedParser` instance. Optional *_factory* is a no-argument |
| 64 | callable that will be called whenever a new message object is needed. It |
| 65 | defaults to the :class:`email.message.Message` class. |
| 66 | |
R David Murray | 3edd22a | 2011-04-18 13:59:37 -0400 | [diff] [blame] | 67 | The *policy* keyword specifies a :mod:`~email.policy` object that controls a |
| 68 | number of aspects of the parser's operation. The default policy maintains |
| 69 | backward compatibility. |
| 70 | |
| 71 | .. versionchanged:: 3.3 Added the *policy* keyword. |
| 72 | |
Benjamin Peterson | e41251e | 2008-04-25 01:59:09 +0000 | [diff] [blame] | 73 | .. method:: feed(data) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 74 | |
Benjamin Peterson | e41251e | 2008-04-25 01:59:09 +0000 | [diff] [blame] | 75 | Feed the :class:`FeedParser` some more data. *data* should be a string |
| 76 | containing one or more lines. The lines can be partial and the |
| 77 | :class:`FeedParser` will stitch such partial lines together properly. The |
| 78 | lines in the string can have any of the common three line endings, |
| 79 | carriage return, newline, or carriage return and newline (they can even be |
| 80 | mixed). |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 81 | |
Benjamin Peterson | e41251e | 2008-04-25 01:59:09 +0000 | [diff] [blame] | 82 | .. method:: close() |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 83 | |
Benjamin Peterson | e41251e | 2008-04-25 01:59:09 +0000 | [diff] [blame] | 84 | Closing a :class:`FeedParser` completes the parsing of all previously fed |
| 85 | data, and returns the root message object. It is undefined what happens |
| 86 | if you feed more data to a closed :class:`FeedParser`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 87 | |
| 88 | |
R. David Murray | 96fd54e | 2010-10-08 15:55:28 +0000 | [diff] [blame] | 89 | .. class:: BytesFeedParser(_factory=email.message.Message) |
| 90 | |
| 91 | Works exactly like :class:`FeedParser` except that the input to the |
| 92 | :meth:`~FeedParser.feed` method must be bytes and not string. |
| 93 | |
| 94 | .. versionadded:: 3.2 |
| 95 | |
| 96 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 97 | Parser class API |
| 98 | ^^^^^^^^^^^^^^^^ |
| 99 | |
| 100 | The :class:`Parser` class, imported from the :mod:`email.parser` module, |
| 101 | provides an API that can be used to parse a message when the complete contents |
| 102 | of the message are available in a string or file. The :mod:`email.parser` |
R David Murray | b35c850 | 2011-04-13 16:46:05 -0400 | [diff] [blame] | 103 | module also provides header-only parsers, called :class:`HeaderParser` and |
| 104 | :class:`BytesHeaderParser`, which can be used if you're only interested in the |
| 105 | headers of the message. :class:`HeaderParser` and :class:`BytesHeaderParser` |
| 106 | can be much faster in these situations, since they do not attempt to parse the |
| 107 | message body, instead setting the payload to the raw body as a string. They |
| 108 | have the same API as the :class:`Parser` and :class:`BytesParser` classes. |
| 109 | |
| 110 | .. versionadded:: 3.3 BytesHeaderParser |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 111 | |
| 112 | |
R David Murray | 3edd22a | 2011-04-18 13:59:37 -0400 | [diff] [blame] | 113 | .. class:: Parser(_class=email.message.Message, *, policy=policy.default) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 114 | |
| 115 | The constructor for the :class:`Parser` class takes an optional argument |
| 116 | *_class*. This must be a callable factory (such as a function or a class), and |
| 117 | it is used whenever a sub-message object needs to be created. It defaults to |
Georg Brandl | 3638e48 | 2009-04-27 16:46:17 +0000 | [diff] [blame] | 118 | :class:`~email.message.Message` (see :mod:`email.message`). The factory will |
| 119 | be called without arguments. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 120 | |
R David Murray | 3edd22a | 2011-04-18 13:59:37 -0400 | [diff] [blame] | 121 | The *policy* keyword specifies a :mod:`~email.policy` object that controls a |
| 122 | number of aspects of the parser's operation. The default policy maintains |
| 123 | backward compatibility. |
| 124 | |
| 125 | .. versionchanged:: 3.3 |
| 126 | Removed the *strict* argument that was deprecated in 2.4. Added the |
| 127 | *policy* keyword. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 128 | |
Benjamin Peterson | e41251e | 2008-04-25 01:59:09 +0000 | [diff] [blame] | 129 | The other public :class:`Parser` methods are: |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 130 | |
| 131 | |
Georg Brandl | 3f076d8 | 2009-05-17 11:28:33 +0000 | [diff] [blame] | 132 | .. method:: parse(fp, headersonly=False) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 133 | |
Benjamin Peterson | e41251e | 2008-04-25 01:59:09 +0000 | [diff] [blame] | 134 | Read all the data from the file-like object *fp*, parse the resulting |
| 135 | text, and return the root message object. *fp* must support both the |
| 136 | :meth:`readline` and the :meth:`read` methods on file-like objects. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 137 | |
Benjamin Peterson | e41251e | 2008-04-25 01:59:09 +0000 | [diff] [blame] | 138 | The text contained in *fp* must be formatted as a block of :rfc:`2822` |
| 139 | style headers and header continuation lines, optionally preceded by a |
| 140 | envelope header. The header block is terminated either by the end of the |
| 141 | data or by a blank line. Following the header block is the body of the |
| 142 | message (which may contain MIME-encoded subparts). |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 143 | |
Benjamin Peterson | e41251e | 2008-04-25 01:59:09 +0000 | [diff] [blame] | 144 | Optional *headersonly* is as with the :meth:`parse` method. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 145 | |
Georg Brandl | 3f076d8 | 2009-05-17 11:28:33 +0000 | [diff] [blame] | 146 | .. method:: parsestr(text, headersonly=False) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 147 | |
Benjamin Peterson | e41251e | 2008-04-25 01:59:09 +0000 | [diff] [blame] | 148 | Similar to the :meth:`parse` method, except it takes a string object |
| 149 | instead of a file-like object. Calling this method on a string is exactly |
R. David Murray | 96fd54e | 2010-10-08 15:55:28 +0000 | [diff] [blame] | 150 | equivalent to wrapping *text* in a :class:`~io.StringIO` instance first and |
Benjamin Peterson | e41251e | 2008-04-25 01:59:09 +0000 | [diff] [blame] | 151 | calling :meth:`parse`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 152 | |
Benjamin Peterson | e41251e | 2008-04-25 01:59:09 +0000 | [diff] [blame] | 153 | Optional *headersonly* is a flag specifying whether to stop parsing after |
| 154 | reading the headers or not. The default is ``False``, meaning it parses |
| 155 | the entire contents of the file. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 156 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 157 | |
R David Murray | 3edd22a | 2011-04-18 13:59:37 -0400 | [diff] [blame] | 158 | .. class:: BytesParser(_class=email.message.Message, *, policy=policy.default) |
R. David Murray | 96fd54e | 2010-10-08 15:55:28 +0000 | [diff] [blame] | 159 | |
| 160 | This class is exactly parallel to :class:`Parser`, but handles bytes input. |
| 161 | The *_class* and *strict* arguments are interpreted in the same way as for |
R David Murray | 3edd22a | 2011-04-18 13:59:37 -0400 | [diff] [blame] | 162 | the :class:`Parser` constructor. |
| 163 | |
| 164 | The *policy* keyword specifies a :mod:`~email.policy` object that |
| 165 | controls a number of aspects of the parser's operation. The default |
| 166 | policy maintains backward compatibility. |
| 167 | |
| 168 | .. versionchanged:: 3.3 |
| 169 | Removed the *strict* argument. Added the *policy* keyword. |
R. David Murray | 96fd54e | 2010-10-08 15:55:28 +0000 | [diff] [blame] | 170 | |
| 171 | .. method:: parse(fp, headeronly=False) |
| 172 | |
| 173 | Read all the data from the binary file-like object *fp*, parse the |
| 174 | resulting bytes, and return the message object. *fp* must support |
| 175 | both the :meth:`readline` and the :meth:`read` methods on file-like |
| 176 | objects. |
| 177 | |
| 178 | The bytes contained in *fp* must be formatted as a block of :rfc:`2822` |
| 179 | style headers and header continuation lines, optionally preceded by a |
| 180 | envelope header. The header block is terminated either by the end of the |
| 181 | data or by a blank line. Following the header block is the body of the |
| 182 | message (which may contain MIME-encoded subparts, including subparts |
| 183 | with a :mailheader:`Content-Transfer-Encoding` of ``8bit``. |
| 184 | |
| 185 | Optional *headersonly* is a flag specifying whether to stop parsing after |
| 186 | reading the headers or not. The default is ``False``, meaning it parses |
| 187 | the entire contents of the file. |
| 188 | |
| 189 | .. method:: parsebytes(bytes, headersonly=False) |
| 190 | |
| 191 | Similar to the :meth:`parse` method, except it takes a byte string object |
| 192 | instead of a file-like object. Calling this method on a byte string is |
| 193 | exactly equivalent to wrapping *text* in a :class:`~io.BytesIO` instance |
| 194 | first and calling :meth:`parse`. |
| 195 | |
| 196 | Optional *headersonly* is as with the :meth:`parse` method. |
| 197 | |
| 198 | .. versionadded:: 3.2 |
| 199 | |
| 200 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 201 | Since creating a message object structure from a string or a file object is such |
R. David Murray | 96fd54e | 2010-10-08 15:55:28 +0000 | [diff] [blame] | 202 | a common task, four functions are provided as a convenience. They are available |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 203 | in the top-level :mod:`email` package namespace. |
| 204 | |
Georg Brandl | a971c65 | 2008-11-07 09:39:56 +0000 | [diff] [blame] | 205 | .. currentmodule:: email |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 206 | |
R David Murray | 3edd22a | 2011-04-18 13:59:37 -0400 | [diff] [blame] | 207 | .. function:: message_from_string(s, _class=email.message.Message, *, \ |
| 208 | policy=policy.default) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 209 | |
| 210 | Return a message object structure from a string. This is exactly equivalent to |
R David Murray | 3edd22a | 2011-04-18 13:59:37 -0400 | [diff] [blame] | 211 | ``Parser().parsestr(s)``. *_class* and *policy* are interpreted as |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 212 | with the :class:`Parser` class constructor. |
| 213 | |
R David Murray | 6a45d3b | 2011-04-18 16:00:47 -0400 | [diff] [blame] | 214 | .. versionchanged:: 3.3 |
| 215 | Removed the *strict* argument. Added the *policy* keyword. |
R David Murray | 3edd22a | 2011-04-18 13:59:37 -0400 | [diff] [blame] | 216 | |
R David Murray | 6a45d3b | 2011-04-18 16:00:47 -0400 | [diff] [blame] | 217 | .. function:: message_from_bytes(s, _class=email.message.Message, *, \ |
| 218 | policy=policy.default) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 219 | |
R. David Murray | 96fd54e | 2010-10-08 15:55:28 +0000 | [diff] [blame] | 220 | Return a message object structure from a byte string. This is exactly |
| 221 | equivalent to ``BytesParser().parsebytes(s)``. Optional *_class* and |
| 222 | *strict* are interpreted as with the :class:`Parser` class constructor. |
| 223 | |
| 224 | .. versionadded:: 3.2 |
R David Murray | 6a45d3b | 2011-04-18 16:00:47 -0400 | [diff] [blame] | 225 | .. versionchanged:: 3.3 |
| 226 | Removed the *strict* argument. Added the *policy* keyword. |
R. David Murray | 96fd54e | 2010-10-08 15:55:28 +0000 | [diff] [blame] | 227 | |
R David Murray | 3edd22a | 2011-04-18 13:59:37 -0400 | [diff] [blame] | 228 | .. function:: message_from_file(fp, _class=email.message.Message, *, \ |
| 229 | policy=policy.default) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 230 | |
Antoine Pitrou | 11cb961 | 2010-09-15 11:11:28 +0000 | [diff] [blame] | 231 | Return a message object structure tree from an open :term:`file object`. |
R David Murray | 3edd22a | 2011-04-18 13:59:37 -0400 | [diff] [blame] | 232 | This is exactly equivalent to ``Parser().parse(fp)``. *_class* |
| 233 | and *policy* are interpreted as with the :class:`Parser` class constructor. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 234 | |
R David Murray | 6a45d3b | 2011-04-18 16:00:47 -0400 | [diff] [blame] | 235 | .. versionchanged:: |
| 236 | Removed the *strict* argument. Added the *policy* keyword. |
R David Murray | 3edd22a | 2011-04-18 13:59:37 -0400 | [diff] [blame] | 237 | |
| 238 | .. function:: message_from_binary_file(fp, _class=email.message.Message, *, \ |
| 239 | policy=policy.default) |
R. David Murray | 96fd54e | 2010-10-08 15:55:28 +0000 | [diff] [blame] | 240 | |
| 241 | Return a message object structure tree from an open binary :term:`file |
| 242 | object`. This is exactly equivalent to ``BytesParser().parse(fp)``. |
R David Murray | 3edd22a | 2011-04-18 13:59:37 -0400 | [diff] [blame] | 243 | *_class* and *policy* are interpreted as with the :class:`Parser` |
R. David Murray | 96fd54e | 2010-10-08 15:55:28 +0000 | [diff] [blame] | 244 | class constructor. |
| 245 | |
| 246 | .. versionadded:: 3.2 |
R David Murray | 6a45d3b | 2011-04-18 16:00:47 -0400 | [diff] [blame] | 247 | .. versionchanged:: 3.3 |
| 248 | Removed the *strict* argument. Added the *policy* keyword. |
R. David Murray | 96fd54e | 2010-10-08 15:55:28 +0000 | [diff] [blame] | 249 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 250 | Here's an example of how you might use this at an interactive Python prompt:: |
| 251 | |
| 252 | >>> import email |
| 253 | >>> msg = email.message_from_string(myString) |
| 254 | |
| 255 | |
| 256 | Additional notes |
| 257 | ^^^^^^^^^^^^^^^^ |
| 258 | |
| 259 | Here are some notes on the parsing semantics: |
| 260 | |
| 261 | * Most non-\ :mimetype:`multipart` type messages are parsed as a single message |
| 262 | object with a string payload. These objects will return ``False`` for |
| 263 | :meth:`is_multipart`. Their :meth:`get_payload` method will return a string |
| 264 | object. |
| 265 | |
| 266 | * All :mimetype:`multipart` type messages will be parsed as a container message |
| 267 | object with a list of sub-message objects for their payload. The outer |
| 268 | container message will return ``True`` for :meth:`is_multipart` and their |
Georg Brandl | 3638e48 | 2009-04-27 16:46:17 +0000 | [diff] [blame] | 269 | :meth:`get_payload` method will return the list of :class:`~email.message.Message` |
| 270 | subparts. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 271 | |
| 272 | * Most messages with a content type of :mimetype:`message/\*` (e.g. |
| 273 | :mimetype:`message/delivery-status` and :mimetype:`message/rfc822`) will also be |
| 274 | parsed as container object containing a list payload of length 1. Their |
| 275 | :meth:`is_multipart` method will return ``True``. The single element in the |
| 276 | list payload will be a sub-message object. |
| 277 | |
| 278 | * Some non-standards compliant messages may not be internally consistent about |
| 279 | their :mimetype:`multipart`\ -edness. Such messages may have a |
| 280 | :mailheader:`Content-Type` header of type :mimetype:`multipart`, but their |
| 281 | :meth:`is_multipart` method may return ``False``. If such messages were parsed |
| 282 | with the :class:`FeedParser`, they will have an instance of the |
| 283 | :class:`MultipartInvariantViolationDefect` class in their *defects* attribute |
| 284 | list. See :mod:`email.errors` for details. |
| 285 | |
| 286 | .. rubric:: Footnotes |
| 287 | |
| 288 | .. [#] As of email package version 3.0, introduced in Python 2.4, the classic |
| 289 | :class:`Parser` was re-implemented in terms of the :class:`FeedParser`, so the |
| 290 | semantics and results are identical between the two parsers. |
| 291 | |