FIX: Disable request membership button if user does not have sufficient trust level.

app/assets/javascripts/discourse/components/group-membership-button.js.es6

@@ -17,6 +17,22 @@ export default Ember.Component.extend({
     }
   },
 
+  @computed
+  disableRequestMembership() {
+    if (this.currentUser) {
+      return this.currentUser.trust_level < this.siteSettings.min_trust_to_send_messages;
+    } else {
+      return false;
+    }
+  },
+
+  @computed("disableRequestMembership")
+  requestMembershipButtonTitle(disableRequestMembership) {
+    if (disableRequestMembership) {
+      return "groups.request_membership_pm.disabled";
+    }
+  },
+
   _showLoginModal() {
     this.sendAction('showLogin');
     $.cookie('destination_url', window.location.href);

app/assets/javascripts/discourse/templates/components/group-membership-button.hbs

@@ -25,7 +25,9 @@
     {{d-button action="requestMembership"
         class="group-index-request"
         icon="envelope"
-        label="groups.request"}}
+        label="groups.request"
+        title=requestMembershipButtonTitle
+        disabled=disableRequestMembership}}
   {{/if}}
 {{else}}
   {{yield}}

config/locales/client.en.yml

@@ -410,6 +410,7 @@ en:
       request_membership_pm:
         title: "Membership Request"
         body: "I would like to apply for membership in @%{groupName}."
+        disabled: "Insufficient trust level to request for group membership"
       name_placeholder: "Group name, no spaces, same as username rule"
       public: "Allow users to join/leave the group freely (Requires group to be visible)"
       empty:

config/site_settings.yml

@@ -821,6 +821,7 @@ trust:
   min_trust_to_send_messages:
     default: 1
     enum: 'TrustLevelSetting'
+    client: true
   tl1_requires_topics_entered: 5
   tl1_requires_read_posts:
     default: 30