Directly manage library from sqlite3?

praimon · 09-02-2016, 03:59 PM

Hello,
Before I do something silly, I have a question:
If I directly manipulate the metadata.db file with sqlite3 (perhaps via a non-python program), will calibre recognize and accept the changes without a problem?

Thank you.

theducks · 09-02-2016, 04:08 PM

Danger Will Robinson

The DB contains everything about YOUR book file.
The program takes care of the needed details. You miss something and

Consider using the CLI tools instead

eschwartz · 09-02-2016, 04:29 PM

If you directly manipulate the db, then it is up to you to make sure you don't break anything... I strongly encourage you to use the `calibredb` CLI backend, or if you need a lot of flexibility, using the calibre apis via `calibre-debug` python scripts. e.g.

Code:

def init_cache(library_path=None):
    if not library_path:
        from calibre.utils.config import prefs
        library_path=prefs['library_path']
    from calibre.db.backend import DB
    from calibre.db.cache import Cache
    backend = DB(library_path)
    cache = Cache(backend)
    cache.init()
    return cache

This grants you access to the functions described in API Documentation for the database interface

praimon · 09-02-2016, 06:42 PM

Thanks for the code example, it was instructive comparing it to the 'official' technique:

Code:

from calibre.library import db
db = db('Path to calibre library folder').new_api

I'm learning python as I read calibre's source, so I'm having some fun. On the other hand, I'm well versed in using sqlite from clojure, so that might actually be the safer option.

eschwartz · 09-02-2016, 07:05 PM

The code I posted is a snippet I got from chaley.

The code in the manual uses a compatibility layer providing the old and new apis, chaley's snippet directly accesses the new database classes... other than that it is basically the same I guess.
Though I have expanded the snippet to default to your currently-configured Calibre Library via prefs.

...

If you are going to use sqlite, you will have to write the functions and validation code to make sure you are modifying the database in accordance with calibre's scheme, but other than that you *should* be fine.
Previous experience with sqlite/clojure may very well trump using existing apis in that case.

Best of luck.

09-02-2016, 03:59 PM	#1
praimon Member Posts: 13 Karma: 10 Join Date: Oct 2013 Device: none	Directly manage library from sqlite3? Hello, Before I do something silly, I have a question: If I directly manipulate the metadata.db file with sqlite3 (perhaps via a non-python program), will calibre recognize and accept the changes without a problem? Thank you.

09-02-2016, 04:29 PM	#3
eschwartz Ex-Helpdesk Junkie Posts: 19,421 Karma: 85397180 Join Date: Nov 2012 Location: The Beaten Path, USA, Roundworld, This Side of Infinity Device: Kindle Touch fw5.3.7 (Wifi only)	If you directly manipulate the db, then it is up to you to make sure you don't break anything... I strongly encourage you to use the `calibredb` CLI backend, or if you need a lot of flexibility, using the calibre apis via `calibre-debug` python scripts. e.g. Code: def init_cache(library_path=None): if not library_path: from calibre.utils.config import prefs library_path=prefs['library_path'] from calibre.db.backend import DB from calibre.db.cache import Cache backend = DB(library_path) cache = Cache(backend) cache.init() return cache This grants you access to the functions described in API Documentation for the database interface

09-02-2016, 06:42 PM	#4
praimon Member Posts: 13 Karma: 10 Join Date: Oct 2013 Device: none	Thanks for the code example, it was instructive comparing it to the 'official' technique: Code: from calibre.library import db db = db('Path to calibre library folder').new_api I'm learning python as I read calibre's source, so I'm having some fun. On the other hand, I'm well versed in using sqlite from clojure, so that might actually be the safer option.

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09-02-2016, 04:08 PM	#2
theducks Well trained by Cats Posts: 29,950 Karma: 55705602 Join Date: Aug 2009 Location: The Central Coast of California Device: Kobo Libra2,Kobo Aura2v1, K4NT(Fixed: New Bat.), Galaxy Tab A	Danger Will Robinson The DB contains everything about YOUR book file. The program takes care of the needed details. You miss something and Consider using the CLI tools instead

09-02-2016, 07:05 PM	#5
eschwartz Ex-Helpdesk Junkie Posts: 19,421 Karma: 85397180 Join Date: Nov 2012 Location: The Beaten Path, USA, Roundworld, This Side of Infinity Device: Kindle Touch fw5.3.7 (Wifi only)	The code I posted is a snippet I got from chaley. The code in the manual uses a compatibility layer providing the old and new apis, chaley's snippet directly accesses the new database classes... other than that it is basically the same I guess. Though I have expanded the snippet to default to your currently-configured Calibre Library via prefs. ... If you are going to use sqlite, you will have to write the functions and validation code to make sure you are modifying the database in accordance with calibre's scheme, but other than that you should be fine. Previous experience with sqlite/clojure may very well trump using existing apis in that case. Best of luck.

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