API to get all field names from the server

src/calibre/srv/code.py

@@ -384,3 +384,13 @@ def tag_browser(ctx, rd):
         return json(ctx, rd, tag_browser, categories_as_json(ctx, rd, db, opts, vl))
 
     return rd.etagged_dynamic_response(etag, generate)
+
+
+@endpoint('/interface-data/field-names/{field}', postprocess=json)
+def field_names(ctx, rd, field):
+    '''
+    Get a list of all names for the specified field
+    Optional: ?library_id=<default library>
+    '''
+    db, library_id = get_library_data(ctx, rd)[:2]
+    return tuple(db.all_field_names(field))

src/pyj/book_list/edit_metadata.pyj

@@ -11,8 +11,8 @@ from book_list.book_details import (
     basic_table_rules, fetch_metadata, field_sorter, no_book, report_load_failure
 )
 from book_list.library_data import (
-    book_metadata, current_library_id, library_data, load_status, loaded_book_ids,
-    set_book_metadata
+    book_metadata, current_library_id, field_names_for, library_data, load_status,
+    loaded_book_ids, set_book_metadata
 )
 from book_list.router import back
 from book_list.top_bar import create_top_bar, set_title
@@ -114,6 +114,23 @@ def simple_line_edit(container_id, book_id, field, fm, div, mi):
         return x
 
 
+def multiple_line_edit(list_to_ui, ui_to_list, container_id, book_id, field, fm, div, mi):
+    nonlocal value_to_json
+    name = fm.name or field
+    le = E.input(type='text', name=name.replace('#', '_c_'), autocomplete=True)
+    le.value = (resolved_metadata(mi, field) or v'[]').join(list_to_ui)
+    form = create_form(le, line_edit_get_value, container_id, book_id, field)
+    div.appendChild(E.div(style='margin: 0.5ex 1rem', _(
+        'Edit the "{0}" below. Multiple items can be separated by {1}.').format(name, list_to_ui.strip())))
+    div.appendChild(E.div(style='margin: 0.5ex 1rem', form))
+    div.appendChild(E.div(style='margin: 0.5ex 1rem'))
+    le.focus(), le.select()
+    value_to_json = def(x):
+        return [a.strip() for a in x.split(ui_to_list) if a.strip()]
+    div.lastChild.appendChild(E.span(_('Loading all {}...').format(name)))
+    field_names_for(field, print)
+
+
 def edit_field(container_id, book_id, field):
     nonlocal value_to_json
     fm = library_data.field_metadata[field]
@@ -125,10 +142,16 @@ def edit_field(container_id, book_id, field):
     d.style.display = 'block'
     d.previousSibling.style.display = 'none'
     clear(d)
-    simple_line_edit(container_id, book_id, field, fm, d, mi)
+    if field is 'authors':
+        multiple_line_edit(' & ', '&', container_id, book_id, field, fm, d, mi)
+    else:
+        simple_line_edit(container_id, book_id, field, fm, d, mi)
     if field is 'title':
         value_to_json = def(x):
             return x or _('Untitled')
+    elif field is 'authors':
+        value_to_json = def(x):
+            return [a.strip() for a in x.split('&') if a.strip()] or [_('Unknown')]
 
 
 def render_metadata(mi, table, container_id, book_id):  # {{{

src/pyj/book_list/library_data.pyj

@@ -73,6 +73,9 @@ def update_library_data(data):
     load_status.ok = True
     load_status.error_html = None
     library_data.previous_book_ids = v'[]'
+    if library_data.for_library is not current_library_id():
+        library_data.field_names = {}
+    library_data.for_library = current_library_id()
     for key in 'search_result sortable_fields field_metadata metadata virtual_libraries book_display_fields'.split(' '):
         library_data[key] = data[key]
     sr = library_data.search_result
@@ -140,6 +143,40 @@ def fetch_init_data():
     load_status.current_fetch.send()
 
 
+def field_names_received(library_id, field, proceed, end_type, xhr, event):
+    if library_id is not current_library_id():
+        return
+    if end_type is not 'load':
+        if end_type is not 'abort':
+            proceed(False, field, xhr.error_html)
+        return
+    try:
+        names = JSON.parse(xhr.responseText)
+    except Exception:
+        import traceback
+        traceback.print_exc()
+        proceed(False, field, 'Invalid JSON from server')
+        return
+    library_data.field_names[field] = {
+        'loading': False,
+        'loaded': True,
+        'last_updated_at': Date.now(),
+        'names': names
+    }
+    proceed(True, field, names)
+
+
+def field_names_for(field, proceed):
+    if library_data.field_names[field] and library_data.field_names[field].loaded:
+        proceed(True, field, library_data.field_names[field].names)
+    if not library_data.field_names[field] or (not library_data.field_names[field].loading and Date.now() - library_data.field_names[field].last_updated_at > 3600 * 1000):
+
+        ajax(f'interface-data/field-names/{encodeURIComponent(field)}', field_names_received.bind(None, current_library_id(), field, proceed), query={'library_id': current_library_id()}).send()
+        if not library_data.field_names[field]:
+            library_data.field_names[field] = {'last_updated_at': 0, 'loaded': False, 'names': v'[]'}
+        library_data.field_names[field].loading = True
+
+
 def thumbnail_url(book_id, width, height):
     return absolute_path(
         'get/thumb/{}/{}?sz={}x{}'.format(