Improved error handling for disapearing custom column linked to read status

cps/admin.py

@@ -474,14 +474,14 @@ def update_table_settings():
     return ""
 
 def check_valid_read_column(column):
-    if column is not "0":
+    if column != "0":
         if not calibre_db.session.query(db.Custom_Columns).filter(db.Custom_Columns.id == column) \
               .filter(and_(db.Custom_Columns.datatype == 'bool', db.Custom_Columns.mark_for_delete == 0)).all():
             return False
     return True
 
 def check_valid_restricted_column(column):
-    if column is not "0":
+    if column != "0":
         if not calibre_db.session.query(db.Custom_Columns).filter(db.Custom_Columns.id == column) \
               .filter(and_(db.Custom_Columns.datatype == 'text', db.Custom_Columns.mark_for_delete == 0)).all():
             return False

cps/static/js/details.js

@@ -22,7 +22,21 @@ $(function() {
 });
 
 $("#have_read_cb").on("change", function() {
-    $(this).closest("form").submit();
+    $.post({
+        url: this.closest("form").action,
+        error: function(response) {
+            var data = [{type:"danger", message:response.responseText}]
+            $("#flash_success").remove();
+            $("#flash_danger").remove();
+            if (!jQuery.isEmptyObject(data)) {
+                data.forEach(function (item) {
+                    $(".navbar").after('<div class="row-fluid text-center" style="margin-top: -20px;">' +
+                        '<div id="flash_' + item.type + '" class="alert alert-' + item.type + '">' + item.message + '</div>' +
+                        '</div>');
+                });
+            }
+        }
+    });
 });
 
 $(function() {

cps/web.py

@@ -185,10 +185,11 @@ def toggle_read(book_id):
                 calibre_db.session.commit()
         except (KeyError, AttributeError):
             log.error(u"Custom Column No.%d is not exisiting in calibre database", config.config_read_column)
+            return "Custom Column No.{} is not exisiting in calibre database".format(config.config_read_column), 400
         except (OperationalError, InvalidRequestError) as e:
             calibre_db.session.rollback()
             log.error(u"Read status could not set: %e", e)
-
+            return "Read status could not set: {}".format(e), 400
     return ""
 
 @web.route("/ajax/togglearchived/<int:book_id>", methods=['POST'])
@@ -1117,12 +1118,19 @@ def adv_search_ratings(q, rating_high, rating_low):
 def adv_search_read_status(q, read_status):
     if read_status:
         if config.config_read_column:
-            if read_status == "True":
-                q = q.join(db.cc_classes[config.config_read_column], isouter=True) \
-                    .filter(db.cc_classes[config.config_read_column].value == True)
-            else:
-                q = q.join(db.cc_classes[config.config_read_column], isouter=True) \
-                    .filter(coalesce(db.cc_classes[config.config_read_column].value, False) != True)
+            try:
+                if read_status == "True":
+                    q = q.join(db.cc_classes[config.config_read_column], isouter=True) \
+                        .filter(db.cc_classes[config.config_read_column].value == True)
+                else:
+                    q = q.join(db.cc_classes[config.config_read_column], isouter=True) \
+                        .filter(coalesce(db.cc_classes[config.config_read_column].value, False) != True)
+            except (KeyError, AttributeError):
+                log.error(u"Custom Column No.%d is not exisiting in calibre database", config.config_read_column)
+                flash(_("Custom Column No.%(column)d is not existing in calibre database",
+                        column=config.config_read_column),
+                      category="error")
+                return q
         else:
             if read_status == "True":
                 q = q.join(ub.ReadBook, db.Books.id == ub.ReadBook.book_id, isouter=True) \