doc: "Troubleshooting" section + minor changes

docs/codesnippets.rst

@@ -82,6 +82,15 @@ See also :class:`Post`, :meth:`Instaloader.download_post`,
 
 Discussed in :issue:`113`.
 
+Top X Posts of User
+-------------------
+
+With Instaloader, it is easy to download the few most-liked pictres of a user.
+
+.. literalinclude:: codesnippets/194_top_x_of_user.py
+
+Discussed in :issue:`194`.
+
 Upgrade Images by Local Copies
 ------------------------------
 

docs/codesnippets/194_top_x_of_user.py

@@ -0,0 +1,15 @@
+from itertools import islice
+from math import ceil
+
+from instaloader import Instaloader, Profile
+
+PROFILE = ...        # profile to download from
+X_percentage = 10    # percentage of posts that should be downloaded
+
+L = Instaloader()
+
+profile = Profile.from_username(L.context, PROFILE)
+posts_sorted_by_likes = sorted(profile.get_posts(), key = lambda p: p.likes + p.comments)
+
+for post in islice(posts_sorted_by_likes, ceil(profile.mediacount * X_percentage / 100)):
+    L.download_post(post, PROFILE)

docs/codesnippets/92_import_firefox_session.py

@@ -0,0 +1,23 @@
+from glob import glob
+from os.path import expanduser
+from sqlite3 import connect
+
+from instaloader import ConnectionException, Instaloader
+
+# FIREFOXCOOKIEFILE = "/home/alex/.mozilla/firefox/l96w6b90.default/cookies.sqlite"
+FIREFOXCOOKIEFILE = glob(expanduser("~/.mozilla/firefox/*.default/cookies.sqlite"))[0]
+
+instaloader = Instaloader(max_connection_attempts=1)
+instaloader.context._session.cookies.update(connect(FIREFOXCOOKIEFILE)
+                                            .execute("SELECT name, value FROM moz_cookies "
+                                                     "WHERE baseDomain='instagram.com'"))
+
+try:
+    username = instaloader.test_login()
+    if not username:
+        raise ConnectionException()
+except ConnectionException:
+    raise SystemExit("Cookie import failed. Are you logged in successfully in Firefox?")
+
+instaloader.context.username = username
+instaloader.save_session_to_file()

docs/contributing.rst

@@ -17,12 +17,14 @@ Reporting Bugs
 If you encounter a bug, do not hesitate to report it in our
 `Issue Tracker <https://github.com/instaloader/instaloader/issues>`__. Since
 Instaloader is actively developed, the majority of bugs is fixed within only
-**3 days** after being reported. When reporting a problem, please keep the
+**4 days** after being reported. When reporting a problem, please keep the
 following in mind:
 
 - Ensure you **use the latest version** of Instaloader. The currently-installed
   version can be found out with ``instaloader --version``.
 
+- Check whether there is a valid solution in our :ref:`troubleshooting` section.
+
 - Briefly **check whether the bug has already been reported**. If you find an
   issue reporting the same bug you encountered, comment there rather than
   opening a new issue. However, if unsure, please create a new issue.

docs/index.rst

@@ -60,6 +60,7 @@ Instaloader Documentation
    cli-options
    as-module
    codesnippets
+   troubleshooting
    contributing
 
 Useful Links

docs/troubleshooting.rst

@@ -0,0 +1,60 @@
+.. _troubleshooting:
+
+Troubleshooting
+===============
+
+.. highlight:: python
+
+429 - Too Many Requests
+-----------------------
+
+Instaloader has a logic to keep track of its requests to Instagram and to obey
+their rate limits. Since they are nowhere documented, we try them out
+experimentally. We have a daily cron job running to confirm that Instaloader
+still stays within the rate limits. Nevertheless, the rate control logic assumes
+that
+
+- at one time, Instaloader is the only application that consumes requests. I.e.
+  neither the Instagram browser interface, nor a mobile app, nor another
+  Instaloader instance is running in parallel,
+
+- no requests had been consumed when Instaloader starts.
+
+The latter one implies that restarting or reinstantiating Instaloader often
+within short time is prone to cause a 429. When a request is denied with a 429,
+Instaloader retries the request as soon as the temporary ban is assumed to be
+expired. In case the retry continuously fails for some reason, which should not
+happen in normal conditions, consider adjusting the
+:option:`--max-connection-attempts` option.
+
+**"Too many queries in the last time"** is not an error. It is a notice that the
+rate limit has almost been reached, according to Instaloader's own rate
+accounting mechanism. We regularly adjust this mechanism to match Instagram's
+current rate limiting.
+
+Login error
+-----------
+
+Instaloader's login *should* work fine, both with and without
+Two-Factor-Authentication. It also supports handling the *checkpoint challenge*,
+issued when Instagram suspects authentication activity on your account, by
+pointing the user to an URL to be opened in a browser.
+
+Nevertheless, in :issue:`92` users report problems with logging in. To still use
+Instaloader's logged-in functionality, you may use the following script to
+workaround login problems by importing the session cookies from Firefox and
+bypassing Instaloader's login.
+
+.. literalinclude:: codesnippets/92_import_firefox_session.py
+
+To use this,
+
+#. login to Instagram in Firefox, 
+
+#. execute the snippet,
+
+#. then, ``instaloader -l USERNAME`` should work fine.
+
+If you do not use your default firefox profile, or your operating system has the
+paths differently set up, you may have to alter the ``FIREFOXCOOKIEFILE``
+variable first.