Save Template Help

[Maverynthia]

So I'm trying to get Calibre to use the first letter of a series name and if not that, the title of the book, only the help docs are archaic to understand and don't provide enough examples.

I found this:
{#series:'ifempty($, field('#genre'))'}

But I'm not using metadata at all, just 'series' or if empty 'title'
Which get's me:
{series:'ifempty($, field("title"))'}/{series} [{series_index}] - {title} ({author})
BUT... where do I put in the '.1' for only the series or title letter.

[eschwartz]

series and title are types of metadata...

I am not entirely clear on what you want to see. Can you give a sample book and how you wish to see it saved?

Also, if you post your template question here: https://www.mobileread.com/forums/sho...d.php?t=100949
on the dedicated templates thread, more people can see and hopefully answer.

[Maverynthia]

I thought that topic was only for POSTING templates not asking about help. Thus the new topic. Maybe this can be merged?

As for what I want, let's take two imaginary books:

The Caterpillar's Day [Happy Bugs #1] by Some Person
There is A Cat Here by That Peep

I basically wanted them sorted into folder's like this:

H/Happy Bugs [1] - The Caterpillar's Day (Some Person)
T/There is A Cat Here (That Peep)

Basically the first letter of the series and if no series then the title becomes the folder, then they are placed in their own folder by series/title
I can get it to do the LETTER for a folder, but I don't know how to set it to fall back on the title if there is no series.

[eschwartz]

No big deal, it works just fine here too. But the other thread is handy since I and several other template gurus are subscribed already, so we are sure to see questions.

To answer your question, template programming mode (that's where we get to use functions) looks like this:

{fieldname:formatting:'function(arguments)'|prefix|suffix}

The four sections -- metadata field, formatting, function(s), and prefix-suffix pair -- are each optional. The ":" divides each section (except the last). The one after "fieldname" is required, even if there is no fieldname, if anyhing other than "{fieldname}" is being used. So if you just use a function, you need to begin with ":" -- same goes with separating the fieldname and prefix-suffix (even though normally there is no separator).

".1" is formatting, so you will want to use

{series:.1:'ifempty($, field("title"))'}/{series}{series_index:| [|] - }{title} ({authors})

I took the liberty of making the brackets space and hyphen around the series_index dependent on there being one, by using a prefix-suffix pair.

[Maverynthia]

OK thanks I'll bookmark this thread for the section breakdown. I don't remember seeing that in the template help, or if it WAS there, it was more confusing than this example.

However when I try to use the code I get:
calibre, version 1.37.0
ERROR: Invalid template:
The template {series:.1:'ifempty($, field("title"))'}/{series}{series_index| [|] - }{title} ({authors}) is invalid:
string indices must be integers, not unicode

[eschwartz]

You're Welcome.

The template help said this in a less straightforward way. I may need to fix that.

[chaley]

Originally Posted by Maverynthia

However when I try to use the code I get:
calibre, version 1.37.0
ERROR: Invalid template:
The template {series:.1:'ifempty($, field("title"))'}/{series}{series_index| [|] - }{title} ({authors}) is invalid:
string indices must be integers, not unicode

You are missing a ":" between "series_index" and its following "|". The template should be

{series:.1:'ifempty($, field("title"))'}/{series}{series_index:| [|] - }{title} ({authors})

[eschwartz]

Thanks chaley! I made a typo.

Fixed in my post, too. I even added an explanation -- is it good?

[chaley]

Originally Posted by eschwartz

Thanks chaley! I made a typo.

Easy to do.

Fixed in my post, too. I even added an explanation -- is it good?

I am the wrong person to ask. Because of a misspent youth studying formal regular languages in the 70s I very much prefer something like extended BNF notation for the syntax of regular languages. I struggle with textual descriptions, translating them in my head to figure out how the language parses. That said, reading yours, it seems correct.

FWIW: here is an extended BNF-like grammar for templates. Text in quotes represent tokens. The square brackets indicate what is between them is optional. I didn't bother with the grammar for the functions. The two variants could be easily expressed in one grammar but I chose not to introduce the or (|) operator.

"{" [ "field name" ] [ [ ":" [ "formatting" ] ] [ ":" "single Function" ] [ "|" [ "prefix" ] "|" [ "suffix" ] ] ] "}"

or

"{" [ "field name" ] [ [ ":" [ "formatting" ] ] [ ":'" "Template Program" "'" ] [ "|" [ "prefix" ] "|" [ "suffix" ] ] ] "}"

Some interesting things to note. According to the grammar:

• {} is a valid template. This is true.
• {:} is also a valid template.
• {::'function()'} is valid
• {::function()} is valid but probably meaningless for semantic reasons. There is no value to pass as the implied first argument.

Well, enough fun.

[eschwartz]

Thanks for the mention of BNF! I've been learning everything myself as I come across stuff -- I learn in my spare time, this isn't part of my curriculum, yet -- so I appreciate any time someone mentions anything I haven't come across yet. (I was wondering a bit what some description were that turns out to be BNF.)

According to Kovid's docs (and thus my understanding),

{authors:uppercase()|prefix|suffix}

is valid but the way you describe it, it must be

{authors:uppercase():|prefix|suffix}

Is this optional, or did you/kovid make a mistake?

I'd test it out myself but I typed this on my Kindle Touch.

[chaley]

Originally Posted by eschwartz

Thanks for the mention of BNF! I've been learning everything myself as I come across stuff -- I learn in my spare time, this isn't part of my curriculum, yet -- so I appreciate any time someone mentions anything I haven't come across yet. (I was wondering a bit what some description were that turns out to be BNF.)

According to Kovid's docs (and thus my understanding),

{authors:uppercase()|prefix|suffix}

is valid but the way you describe it, it must be

{authors:uppercase():|prefix|suffix}

Is this optional, or did you/kovid make a mistake?

I'd test it out myself but I typed this on my Kindle Touch.

I made a mistake in the grammar. That colon should not precede the bar.

It should be

"{" [ "field name" ] [ [ ":" [ "formatting" ] ] [ ":" "single Function" ] [ "|" [ "prefix" ] "|" [ "suffix" ] ] ] "}"

or

"{" [ "field name" ] [ [ ":" [ "formatting" ] ] [ ":'" "Template Program" "'" ] [ "|" [ "prefix" ] "|" [ "suffix" ] ] ] "}"

I think I messed up because I was struggling to deal with the alternation for Template Program Mode and for the optional formatting. Or perhaps because my brain no longer works as well as it once did.