Insert metadata: Allow showing identifiers such as ISBN in the jacket page template

resources/jacket/template.xhtml

@@ -39,6 +39,13 @@
                 </tr>
                 <tr data-calibre-jacket-searchable-tags="1" style="color:white; display:none"><td colspan="2">{searchable_tags}</td></tr>
             </table>
+			<!-- 
+                If you want to insert the identifiers you can do so either as a
+                comma separated list of links, just like they are displayed in
+                the Book details panel, or as individual entries, for example::
+				<div style="display: {display.identifiers}">{identifiers.links}</div>
+				<div style="display: {identifiers.display.isbn}">{identifiers.isbn}</div>
+			-->
             <div class="cbj_footer">{footer}</div>
         </div>
         <hr class="cbj_kindle_banner_hr" />

src/calibre/ebooks/oeb/transforms/jacket.py

@@ -6,19 +6,24 @@ __license__   = 'GPL v3'
 __copyright__ = '2009, Kovid Goyal <kovid@kovidgoyal.net>'
 __docformat__ = 'restructuredtext en'
 
-import sys, os, re
-from xml.sax.saxutils import escape
+import os
+import re
+import sys
 from string import Formatter
+from xml.sax.saxutils import escape
 
-from calibre import guess_type, strftime
+from calibre import guess_type, prepare_string_for_xml, strftime
 from calibre.constants import iswindows
-from calibre.ebooks.oeb.base import XPath, XHTML_NS, XHTML, xml2text, urldefrag, urlnormalize
-from calibre.library.comments import comments_to_html, markdown
-from calibre.utils.date import is_date_undefined, as_local_time
-from calibre.utils.icu import sort_key
 from calibre.ebooks.chardet import strip_encoding_declarations
 from calibre.ebooks.metadata import fmt_sidx, rating_to_stars
-from polyglot.builtins import unicode_type, map
+from calibre.ebooks.metadata.sources.identify import urls_from_identifiers
+from calibre.ebooks.oeb.base import (
+    XHTML, XHTML_NS, XPath, urldefrag, urlnormalize, xml2text
+)
+from calibre.library.comments import comments_to_html, markdown
+from calibre.utils.date import as_local_time, is_date_undefined
+from calibre.utils.icu import sort_key
+from polyglot.builtins import map, unicode_type
 
 JACKET_XPATH = '//h:meta[@name="calibre-content" and @content="jacket"]'
 
@@ -235,6 +240,24 @@ class Attributes:
         return 'none'
 
 
+class Identifiers:
+
+    def __init__(self, idents):
+        self.identifiers = idents or {}
+        self.display = Attributes()
+        for k in self.identifiers:
+            setattr(self.display, k, 'initial')
+        links = []
+        for x in urls_from_identifiers(self.identifiers):
+            name, id_typ, id_val, url = (prepare_string_for_xml(e, True) for e in x)
+            links.append(f'<a href="{url}" title="{id_typ}:{id_val}">{name}</a>')
+        self.links = ', '.join(links)
+        self.display.links = 'initial' if self.links else 'none'
+
+    def __getattr__(self, name):
+        return self.identifiers.get(name, '')
+
+
 def render_jacket(mi, output_profile,
         alt_title=_('Unknown'), alt_tags=[], alt_comments='',
         alt_publisher='', rescale_fonts=False, alt_authors=None):
@@ -291,6 +314,7 @@ def render_jacket(mi, output_profile,
         display = Attributes()
         args = dict(xmlns=XHTML_NS,
             title_str=title_str,
+            identifiers=Identifiers(mi.identifiers),
             css=css,
             title=title,
             author=author,
@@ -352,6 +376,8 @@ def render_jacket(mi, output_profile,
         for k, v in has_data.items():
             setattr(display, k, 'initial' if v else 'none')
         display.title = 'initial'
+        if mi.identifiers:
+            display.identifiers = 'initial'
 
         formatter = SafeFormatter()
         generated_html = formatter.format(template, **args)