Expected behaviour:

convert_magnet plugin converts magnet uri into torrent file

Actual behaviour:

convert_magnet plugin does not convert magnet uri into torrent file (see log lines) due to incompatibility in libtorrent python bindings

Steps to reproduce:

• Step 1: run flexget execute

Config:

schedules:
  - tasks: '*'
    interval:
      minutes: 1

tasks:
  test task:
    rss: http://rarbg.to/rssdd.php
    accept_all: yes
    download: /downloads/
    convert_magnet: yes

Log:

2019-08-02 22:00 INFO     convert_magnet test task       Converting entry ------------------ magnet URI to a torrent file
2019-08-02 22:00 ERROR    convert_magnet test task       Unable to convert Magnet URI for entry ------------------:
    Python argument types in libtorrent.add_magnet_uri(session, str, add_torrent_params) did not match C++ signature:
    add_magnet_uri(libtorrent::session {lvalue}, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::python::dict)

Additional information:

• FlexGet version: 2.21.15
• Python version: 3.7.4
• Installation method: pip
• Using daemon (yes/no): yes
• OS and version: alpine 3.10
• Link to crash log: if you really want it I can provide one, but I think the error message in the log speaks for itself

So, in my case this function is failing. According to the libtorrent docs, the method called add_magnet_uri is actually deprecated (I don't know since when). Though I find it odd to update a deprecated function, the documentation also offers an alternative way of doing things:

A simpler way to add a magnet link to a session is to pass in the link through add_torrent_params::url argument to session::add_torrent().

I think I got it working making these changes:

-        handle = libtorrent.add_magnet_uri(session, magnet_uri, params)
+        params.url = magnet_uri
+        handle = session.add_torrent(params)

However, it seems a large number of libtorrent versions are supported and I have no way of knowing for how many other people running older versions this change will actually break. To be on the safe side, we can add a version check to get the handle value in this way.

Software installed:

# apk list | grep "libtorrent\|boost" | grep installed
boost-python3-1.69.0-r5 x86_64 {boost} (custom) [installed]
boost-system-1.69.0-r5 x86_64 {boost} (custom) [installed]
libtorrent-rasterbar-1.2.1-r0 x86_64 {libtorrent-rasterbar} (BSD-3-Clause) [installed]
py3-libtorrent-rasterbar-1.2.1-r0 x86_64 {libtorrent-rasterbar} (BSD-3-Clause) [installed]

Can somebody verify my assumptions and make a PR ?

Edit
The reason I wrote it as params.url = instead of params['url'] = (like the info_hash) is because this raised an error:

TypeError: 'add_torrent_params' object does not support item assignment