UI - Edit - Live Preview - improve error handling

changedetectionio/blueprint/ui/edit.py

@@ -312,8 +312,27 @@ def construct_blueprint(datastore: ChangeDetectionStore, update_q, queuedWatchMe
         '''For when viewing the "preview" of the rendered text from inside of Edit'''
         from flask import jsonify
         from changedetectionio.processors.text_json_diff import prepare_filter_prevew
-        result = prepare_filter_prevew(watch_uuid=uuid, form_data=request.form, datastore=datastore)
-        return jsonify(result)
+
+        watch = datastore.data["watching"].get(uuid)
+
+        if not watch:
+            return jsonify({
+                "error": "Watch not found",
+                "code": 400
+            }), 400
+
+        if not watch.history_n:
+            return jsonify({
+                "error": "Watch has empty history, at least one fetch of the page is required.",
+                "code": 400
+            }), 400
+        #
+        try:
+            result = prepare_filter_prevew(watch_uuid=uuid, form_data=request.form, datastore=datastore)
+            return jsonify(result)
+        except Exception as e:
+            return abort(500, str(e))
+
 
     @edit_blueprint.route("/highlight_submit_ignore_url", methods=['POST'])
     @login_optionally_required

changedetectionio/static/js/watch-settings.js

@@ -21,6 +21,7 @@ function request_textpreview_update() {
         namespace: 'watchEdit'
     }).done(function (data) {
         console.debug(data['duration'])
+        $('#error-text').text('');
         $('#filters-and-triggers #text-preview-before-inner').text(data['before_filter']);
         $('#filters-and-triggers #text-preview-inner')
             .text(data['after_filter'])
@@ -37,9 +38,8 @@ function request_textpreview_update() {
     }).fail(function (error) {
         if (error.statusText === 'abort') {
             console.log('Request was aborted due to a new request being fired.');
-        } else {
-            $('#filters-and-triggers #text-preview-inner').text('There was an error communicating with the server.');
         }
+        $('#error-text').text(error.responseJSON['error']);
     })
 }
 

changedetectionio/templates/edit.html

@@ -363,6 +363,7 @@ Math: {{ 1 + 1 }}") }}
                           </div>
                       </div>
                     </div>
+                  <p id="error-text"></p>
             </div>
           </div>
         </div>