calibre python script to update custom fields (help)

[mactastik]

I'm working on converting over from goodreads to calibre. So far, so good. One of the things I'd like is two custom fields: Read and Stars to match whether I've read the book or not and the stars I give the book.

I was able to make the fields and can set them manually in Calibre no problem. I can read in and match books pretty well, but I can't seem to store the custom fields via python. Here's what I have (in brief):

metadata = calibre_db.get_metadata(id)
stars = metadata.get_user_metadata("#stars", True)
stars["#value#"] = 4
metadata.set_user_metadata("#stars", stars)
read = metadata.get_user_metadata("#read", True)
read["#value#"] = True
metadata.set_user_metadata("#read", read)

I can print values that I've manually entered, so I know I'm reading the right things, but setting doesn't seem to work. What am I missing?

[mactastik]

Since it's not much longer, though this would benefit from a more complete test script:

# Run with calibre-debug -e calibre_filler.py
import calibre.library

LIBRARY = "calibre/andy"

calibre_db = calibre.library.db(LIBRARY).new_api

# calibre_books = get_calibre_books()
metadata = calibre_db.get_metadata(291)
stars = metadata.get_user_metadata("#stars", True)
stars["#value#"] = 7  # values are 0 to 10
read = metadata.get_user_metadata("#read", True)
read["#value#"] = True
print(f"   Update metadata from [{stars['#value#']}] [{read['#value#']}]")
metadata.set_user_metadata("#stars", stars)
metadata.set_user_metadata("#read", read)

It reads the values fine but doesn't store them in the database. Is there a "write" command of some kind I'm not aware of?

[kovidgoyal]

calibre_db.set_metadata or set_field

[mactastik]

Thanks. I'm still unclear on how this works.

https://manual.calibre-ebook.com/db_api.html
Is this the only documentation?

set_metadata requires an "mi" (Metadata object), which I assume is the *full* metadata for the book (because it says that you need to specify None if you don't want a given field replaced). But I don't see where the Metadata object itself is documented, so I'm not sure how to index into it to edit just the user-defined fields.

Similarly, set_field asks for a "mapping of book id's to values". What is that? And what is the "name" of the field if it's a user-defined field?

[chaley]

Originally Posted by mactastik

Similarly, set_field asks for a "mapping of book id's to values". What is that? And what is the "name" of the field if it's a user-defined field?

The "mapping" is documented in the set_field comments.

:param book_id_to_val_map: Mapping of book_ids to values that should be applied.

It is a python dict (map) from book id to value. Books with an id in the dict will have the field value changed to that id's value in the dict.

The name of the field is the lookup name, #something for custom columns.

[chaley]

BTW:

• Using get_proxy_metadata() is much more efficient in this case than get_metadata.
• In your case, using set_field() is much easier than set_metadata. You deal with books and values, not Metadata instances.

[chaley]

Moderator Notice
Moved to the development subforum

[mactastik]

I see. Looks like a quick test of set_field does work well. Thanks!