Update '/' endpoint to return json

Very useful for test purpose, we have to bench and test that endpoint
to ensure that the main feature works fine. From test part this is
easier to deal with json object.

README.rst

@@ -20,6 +20,7 @@ with one command.
 
 - Run the docker-compose **up** command to start the project ``docker-compose up --build``
 - Getting the ip of the spot service and go to http://<spot-ip>:8888
+- Or you can use the command line ``curl -X POST -F 'category=general' -F 'language=en-US' -F 'q=lequipe' -F 'time_range=' -F 'output=json' http://<spot-ip>:8888/``
 
 .. note::  Here the command to get the IP of the spot service
  ``docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' my-spot_spot_1``

searx/webapp.py

@@ -452,21 +452,26 @@ def config_results(results, query):
                 result['publishedDate'] = format_date(publishedDate)
 
 
-def index_error():
-    request.errors.append(gettext('search error'))
-    return render(
-        'index.html',
-    )
+def index_error(exn, output):
+    user_error = gettext("search error")
+    if output == "json":
+        return jsonify({"error": f"{user_error}: {exn}"})
+
+    request.errors.append(user_error)
+    return render('index.html')
 
 
 @app.route('/search', methods=['GET', 'POST'])
 @app.route('/', methods=['GET', 'POST'])
 def index():
+    # check the response format
+    output = request.form.get("output", "html")
+
     # check if there is query
     if request.form.get('q') is None:
-        return render(
-            'index.html',
-        )
+        if output == 'json':
+            return jsonify({}), 204
+        return render('index.html')
 
     selected_category = request.form.get('category') or 'general'
     first_page = request.form.get('pageno')
@@ -489,9 +494,9 @@ def index():
 
         # is it an invalid input parameter or something else ?
         if issubclass(e.__class__, SearxParameterException):
-            return index_error(), 400
+            return index_error(e, output), 400
         else:
-            return index_error(), 500
+            return index_error(e, output), 500
 
     if is_general_first_page:
         result_copy = copy.copy(search_data.results)
@@ -512,8 +517,7 @@ def index():
     config_results(images, search_data.query)
     config_results(videos, search_data.query)
 
-    return render(
-        'results.html',
+    response = dict(
         results=search_data.results,
         q=search_data.query,
         selected_category=selected_category,
@@ -521,12 +525,12 @@ def index():
         time_range=search_data.time_range,
         number_of_results=format_decimal(search_data.results_number),
         advanced_search=request.form.get('advanced_search', None),
-        suggestions=search_data.suggestions,
-        answers=search_data.answers,
-        corrections=search_data.corrections,
+        suggestions=list(search_data.suggestions),
+        answers=list(search_data.answers),
+        corrections=list(search_data.corrections),
         infoboxes=search_data.infoboxes,
         paging=search_data.paging,
-        unresponsive_engines=search_data.unresponsive_engines,
+        unresponsive_engines=list(search_data.unresponsive_engines),
         current_language=match_language(search_data.language,
                                         LANGUAGE_CODES,
                                         fallback=settings['search']['language']),
@@ -536,6 +540,9 @@ def index():
         theme=get_current_theme_name(),
         favicons=global_favicons[themes.index(get_current_theme_name())]
     )
+    if output == 'json':
+        return jsonify(response)
+    return render('results.html', **response)
 
 
 @app.route('/about', methods=['GET'])