[Einix]

Hi all,
I am using calibre for a while now. Love it, Thanks for all the good work. Also thanks for the many plugins.
There are a few things I would like to get done. So I looked into the plugin development. Downloaded the demo code. And voila: It didn't work ?
I tried the simple hello_world __init__.py demo, it seems to update the publisher temporarily, but some doesn't save it permanently.

Then I tried the interface demo. Same effect here.
I added some prints for debugging, I am running under Linux, I changed the demo:

def update_title(self):
'''
Set the metadata in the files in the selected book's record to
match the current metadata in the database.
'''
from calibre.ebooks.metadata.meta import set_metadata, get_metadata
from calibre.gui2 import error_dialog, info_dialog

# Get currently selected books
rows = self.gui.library_view.selectionModel().selectedRow s()
if not rows or len(rows) == 0:
return error_dialog(self.gui, 'Cannot update metadata', 'No books selected', show=True)
# Map the rows to book ids
ids = list(map(self.gui.library_view.model().id, rows))
db = self.db.new_api
for book_id in ids:
# Get the current metadata for this book from the db
mi = db.get_metadata(book_id, get_cover=True, cover_as_data=True)
fmts = db.formats(book_id)
if not fmts:
continue
for fmt in fmts:
# Get a python file object for the format. This will be either
# an in memory file or a temporary on disk file
ffile = db.format(book_id, fmt, as_file=True)
ffile.seek(0)
print ("Original Publisher: ", mi.publisher)


#change value
mi.publisher = "Test Publisher"

# Set metadata in the format
set_metadata(ffile, mi, fmt)
ffile.seek(0)
print ("Updated Publisher: ", mi.publisher)

# Now replace the file in the calibre library with the updated
# file. We dont use add_format_with_hooks as the hooks were
# already run when the file was first added to calibre.
db.add_format(book_id, fmt, ffile, run_hooks=False)

print ("Refreshed Publisher: ", mi.publisher)

info_dialog(self, 'Updated files', 'Updated the metadata in the files of %d book(s)'%len(ids), show=True)

the debug output is:
einix@Eva:~/workspace/interface_demo_plugin> calibre-customize -b . & calibre-debug -g
[1] 20151
calibre 3.27.1 embedded-python: False is64bit: True
Linux-4.12.14-lp150.12.22-default-x86_64-with-glibc2.2.5 Linux ('64bit', '')
('Linux', '4.12.14-lp150.12.22-default', '#1 SMP Sat Oct 13 05:05:16 UTC 2018 (09415e8)')
Python 2.7.14
Linux: ('', '', '')
Interface language: en_GB
Plugin updated: Interface Plugin Demo (1, 0, 0)
Successfully initialized third party plugins: Quality Check (1, 9, 11) && EpubSplit (2, 4, 0) && Interface Plugin Demo (1, 0, 0) && Find Duplicates (1, 6, 3)
Not controlling automatic hidpi scaling
devicePixelRatio: 1.0
logicalDpi: 96.3794466403 x 96.4556962025
physicalDpi: 93.7846153846 x 95.25
Using calibre Qt style: True
[0.00] Starting up...
[0.03] Showing splash screen...
[2.06] splash screen shown
[2.06] Initializing db...
[2.08] db initialized
[2.08] Constructing main UI...
libpng warning: iCCP: known incorrect sRGB profile
libpng warning: iCCP: known incorrect sRGB profile
Looking for desktop notifier support from: org.freedesktop.Notifications
org.freedesktop.Notifications found in 0.0 seconds
[4.76] main UI initialized...
[4.76] Hiding splash screen
[5.11] splash screen hidden
[5.11] Started up in 5.11 seconds with 1 books

"First run"
Original Publisher: Blackmore Dennett
Updated Publisher: Test Publisher
Refreshed Publisher: Test Publisher
Original Publisher: Test Publisher
Updated Publisher: Test Publisher
Refreshed Publisher: Test Publisher

Also why would the print be repeated twice?

"and if I press the button again":

Original Publisher: Blackmore Dennett
Updated Publisher: Test Publisher
Refreshed Publisher: Test Publisher
Original Publisher: Test Publisher
Updated Publisher: Test Publisher
Refreshed Publisher: Test Publisher

So it reads the old metadata back, not the new one? Is there any switch I need to flip to get changes actually written?
And would that write to the opf file or the database? (I checked both no updates)
Thanks guys