Enhancement #1961464: add ability to import and export the edit metadata custom column field list.

src/calibre/gui2/custom_column_widgets.py

@@ -759,10 +759,13 @@ def column_is_comments(key, fm):
             fm[key].get('display', {}).get('interpret_as') != 'short-text')
 
 
-def get_field_list(db, use_defaults=False):
+def get_field_list(db, use_defaults=False, pref_data_override=None):
     fm = db.field_metadata
     fields = fm.custom_field_keys(include_composites=False)
-    displayable = db.prefs.get('edit_metadata_custom_columns_to_display', None)
+    if pref_data_override is not None:
+        displayable = pref_data_override
+    else:
+        displayable = db.prefs.get('edit_metadata_custom_columns_to_display', None)
     if use_defaults or displayable is None:
         fields.sort(key=partial(field_sort_key, fm=fm))
         return [(k, True) for k in fields]

src/calibre/gui2/preferences/look_feel.py

@@ -21,7 +21,7 @@ from calibre import human_readable
 from calibre.ebooks.metadata.book.render import DEFAULT_AUTHOR_LINK
 from calibre.constants import ismacos, iswindows
 from calibre.ebooks.metadata.sources.prefs import msprefs
-from calibre.gui2 import default_author_link
+from calibre.gui2 import default_author_link, choose_save_file, choose_files
 from calibre.gui2.custom_column_widgets import get_field_list as em_get_field_list
 from calibre.gui2.dialogs.template_dialog import TemplateDialog
 from calibre.gui2.preferences import ConfigWidgetBase, test_widget, CommaSeparatedList
@@ -333,10 +333,10 @@ class EMDisplayedFields(DisplayedFields):  # {{{
     def __init__(self, db, parent=None):
         DisplayedFields.__init__(self, db, parent)
 
-    def initialize(self, use_defaults=False):
+    def initialize(self, use_defaults=False, pref_data_override=None):
         self.beginResetModel()
         self.fields = [[x[0], x[1]] for x in
-                em_get_field_list(self.db, use_defaults=use_defaults)]
+                em_get_field_list(self.db, use_defaults=use_defaults, pref_data_override=pref_data_override)]
         self.endResetModel()
         self.changed = True
 
@@ -567,6 +567,9 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
                 lambda self: move_field_up(self.em_display_order, self.em_display_model))
         connect_lambda(self.em_down_button.clicked, self,
                 lambda self: move_field_down(self.em_display_order, self.em_display_model))
+        self.em_export_layout_button.clicked.connect(self.em_export_layout)
+        self.em_import_layout_button.clicked.connect(self.em_import_layout)
+        self.em_reset_layout_button.clicked.connect(self.em_reset_layout)
 
         self.qv_display_model = QVDisplayedFields(self.gui.current_db,
                 self.qv_display_order)
@@ -640,6 +643,36 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
         self.sections_view.setHorizontalScrollBarPolicy(Qt.ScrollBarPolicy.ScrollBarAlwaysOff)
         self.tabWidget.currentWidget().setFocus(Qt.FocusReason.OtherFocusReason)
 
+    def em_export_layout(self):
+        filename = choose_save_file(self, 'em_import_export_field_list',
+                _('Save column list to file'),
+                filters=[(_('Column list'), ['json'])])
+        if filename:
+            try:
+                with open(filename, 'w') as f:
+                    json.dump(self.em_display_model.fields, f, indent=1)
+            except Exception as err:
+                error_dialog(self, _('Export field layout'),
+                             _('<p>Could not write field list. Error:<br>%s')%err, show=True)
+
+    def em_import_layout(self):
+        filename = choose_files(self, 'em_import_export_field_list',
+                _('Load column list from file'),
+                filters=[(_('Column list'), ['json'])])
+        if filename:
+            try:
+                with open(filename[0]) as f:
+                    fields = json.load(f)
+                self.em_display_model.initialize(pref_data_override=fields)
+                self.changed_signal.emit()
+            except Exception as err:
+                error_dialog(self, _('Import layout'),
+                             _('<p>Could not read field list. Error:<br>%s')%err, show=True)
+
+    def em_reset_layout(self):
+        self.em_display_model.initialize(use_defaults=True)
+        self.changed_signal.emit()
+
     def choose_icon_theme(self):
         from calibre.gui2.icon_theme import ChooseTheme
         d = ChooseTheme(self)

src/calibre/gui2/preferences/look_feel.ui

@@ -987,6 +987,47 @@ A value of zero means calculate automatically.</string>
             </property>
            </widget>
           </item>
+          <item row="5" column="0">
+           <layout class="FlowLayout">
+            <item>
+             <widget class="QPushButton" name="em_export_layout_button">
+              <property name="text">
+               <string>Export list</string>
+              </property>
+              <property name="toolTip">
+               <string>&lt;p&gt;Click this button to write the current display
+settings to a file. This could be useful if you have several libraries with similar
+structure and you want to use the same column order for each one.&lt;/p&gt;</string>
+              </property>
+             </widget>
+            </item>
+            <item>
+             <widget class="QPushButton" name="em_import_layout_button">
+              <property name="text">
+               <string>Import list</string>
+              </property>
+              <property name="toolTip">
+               <string>&lt;p&gt;Click this button to set the list to one
+previously exported. This could be useful if you have several libraries with
+similar structure and you want to use the same column order for each one. Columns
+in the imported list that aren't in the current library are ignored. Columns in
+the library that are not in the imported list are put at the end and marked
+as displayable.&lt;/p&gt;</string>
+              </property>
+             </widget>
+            </item>
+            <item>
+             <widget class="QPushButton" name="em_reset_layout_button">
+              <property name="text">
+               <string>Reset list</string>
+              </property>
+              <property name="toolTip">
+               <string>&lt;p&gt;Click this button to reset the list to its default order.&lt;/p&gt;</string>
+              </property>
+             </widget>
+            </item>
+           </layout>
+          </item>
          </layout>
         </widget>
        </item>
@@ -1624,6 +1665,11 @@ column being examined (the left-hand pane)</string>
    <header>calibre/gui2/widgets2.h</header>
    <container>1</container>
   </customwidget>
+  <customwidget>
+   <class>FlowLayout</class>
+   <extends>QLayout</extends>
+   <header>calibre/gui2/widgets2.h</header>
+  </customwidget>
  </customwidgets>
  <resources>
   <include location="../../../../resources/images.qrc"/>