[Comfy.n]

Originally Posted by chaley

I may have confused things, but lets put that aside.

I have an implementation that doesn't require the temporary VL but respects the current VL. It is a bit more complicated because I wanted to generalize it to any field, not just authors. To use what I describe below you must be running calibre 7.7 or later.

To use it, make a stored template named whatever you want -- I use "get_one_book_per_field_value". The template itself is:

Spoiler:

python:
def evaluate(book, context):
	field_name = context.arguments[0] if len(context.arguments) == 1 else None
	if field_name is None:
		raise NameError("The argument 'field' wasn't provided")

	db = context.db.new_api
	# Check if we have already computed the necessary data
	book_ids = context.globals.get('book_ids', None)
	if book_ids is None:
		candidates = context.globals.get('_candidates', db.all_book_ids())
		books = {}
		for book_id in db.search(query=''): # restrict the search to the current VL
			if book_id not in candidates:
				continue
			item_values = db.field_for(field_name, book_id)
			if item_values is None:
				continue
			if isinstance(item_values, str):
				item_values = (item_values,)
			for item_val in item_values:
				if item_val not in books or books[item_val]['count'] > len(item_values):
					books.pop(item_val, None)
					books[item_val] = {'count': len(item_values), 'book_id': book_id}
		context.globals['book_ids'] = frozenset(bn['book_id'] for bn in books.values())

	# Check if the current book is to be displayed
	book_ids = context.globals['book_ids']
	return '1' if book.id in book_ids else ''

This template takes one argument, the field (column) you are interested in (authors).

Next, make this template search:

template:"""program: get_one_book_per_field_value('authors')#@#:b:yes"""

It calls the above stored template with the argument "authors". I recommend you create a saved search with it. I did and named it "one_book_per_author". You now have @Katja_hbg's B.

You also need @Katja_hbg's A. To get it, put this in a stored template named what you want. I named it "item_has_notes". The template is

Spoiler:

python:
def evaluate(book, context):
	field_name = context.arguments[0] if len(context.arguments) == 1 else None
	if field_name is None:
		raise NameError("The argument for the field name wasn't provided")

	db = context.db.new_api
	items_with_notes = context.globals.get('items_with_notes')
	if items_with_notes is None:
		items_with_notes = db.get_all_items_that_have_notes(field_name)
		context.globals['items_with_notes'] = items_with_notes
		context.globals['item_name_map'] = db.get_item_name_map(field_name)
	item_name_map = context.globals['item_name_map']

	vals = book.get(field_name)
	if vals is None:
		return ''
	if isinstance(vals, str):
		vals = tuple((vals,))
	for val in vals:
		if item_name_map.get(val) in items_with_notes:
			return '1'
	return ''

This template also takes 1 argument, the field (column) name.

Now make another template search

template:"""program: item_has_notes('authors')#@#:b:yes"""

This calles the stored template with the field name "authors". Again, I recommend you save it as a search. I did that, naming it "author has notes".

You can now do searches like:

• search:"=author has notes" and search:one_book_per_author
• formats:epub and tags:foobar and search:one_book_per_author
• search:one_book_per_author

All of this works for me. I hope it works for you.

Hi @chaley,

Could you please create a similar template to search for each author that has a Link and return only one book per author?