fix admin site add new mastodon issue

mastodon/admin.py

@@ -23,7 +23,7 @@ class MastodonApplicationModelAdmin(admin.ModelAdmin):
                     (not bool(request.POST.get('is_proxy')) and bool(request.POST.get('proxy_to'))):
                     request.POST['domain_name'] = _("请同时填写is_proxy和proxy_to。")
                 else:
-                    if request.POST['is_proxy']:
+                    if request.POST.get("is_proxy"):
                         try:
                             origin = MastodonApplication.objects.get(domain_name=request.POST['proxy_to'])
                             # set proxy credentials to those of its original site

users/templates/users/login.html

@@ -37,7 +37,7 @@
             {% if user.is_authenticated %}
             <a href="{% url 'common:home' %}" class="button">{% trans '前往我的主页' %}</a>
             {% else %}            
-            <select name="sites" id="sitesSelect">
+            <select name="sites" id="sitesSelect" placeholder="test">
                 {% for site in sites %}
                 <option value="{{ site.domain_name }}" data-client-id="{{ site.client_id }}">@{{ site.domain_name }}</option>
                 {% endfor %}
@@ -49,9 +49,15 @@
 
     </div>
     {% if not user.is_authenticated %}
+    
+    
     <script>
         // $("#sitesSelect").chosen();
+        {% if selected_site %}
         $("#sitesSelect").val("{{ selected_site }}");
+        {% else %}
+        $("#sitesSelect").val($("#sitesSelect option:first").val());
+        {% endif %}
         $("button[name=login]").click(function(e) {
             e.preventDefault();
             let selected =  $("#sitesSelect").find(":selected");