FEATURE: new 'simultaneous_uploads' site setting

app/assets/javascripts/discourse/components/composer-editor.js.es6

@@ -618,7 +618,6 @@ export default Ember.Component.extend({
 
   _bindUploadTarget() {
     this._unbindUploadTarget(); // in case it's still bound, let's clean it up first
-
     this._pasted = false;
 
     const $element = this.$();
@@ -649,12 +648,23 @@ export default Ember.Component.extend({
     });
 
     $element.on("fileuploadsubmit", (e, data) => {
+      const max = this.siteSettings.simultaneous_uploads;
+
+      // Limit the number of simultaneous uploads
+      if (max > 0 && data.files.length > max) {
+        bootbox.alert(
+          I18n.t("post.errors.too_many_dragged_and_dropped_files", { max })
+        );
+        return false;
+      }
+
       // Look for a matching file upload handler contributed from a plugin
       const matcher = handler => {
         const ext = handler.extensions.join("|");
         const regex = new RegExp(`\\.(${ext})$`, "i");
         return regex.test(data.files[0].name);
       };
+
       const matchingHandler = uploadHandlers.find(matcher);
       if (data.files.length === 1 && matchingHandler) {
         matchingHandler.method(data.files[0]);

app/assets/javascripts/discourse/mixins/upload.js.es6

@@ -34,7 +34,10 @@ export default Em.Mixin.create({
     const $upload = this.$();
     const reset = () =>
       this.setProperties({ uploading: false, uploadProgress: 0 });
-    const maxFiles = this.getWithDefault("maxFiles", 10);
+    const maxFiles = this.getWithDefault(
+      "maxFiles",
+      this.siteSettings.simultaneous_uploads
+    );
 
     $upload.on("fileuploaddone", (e, data) => {
       let upload = data.result;
@@ -56,8 +59,12 @@ export default Em.Mixin.create({
     );
 
     $upload.on("fileuploaddrop", (e, data) => {
-      if (data.files.length > maxFiles) {
+      if (maxFiles > 0 && data.files.length > maxFiles) {
-        bootbox.alert(I18n.t("post.errors.too_many_dragged_and_dropped_files"));
+        bootbox.alert(
+          I18n.t("post.errors.too_many_dragged_and_dropped_files", {
+            max: maxFiles
+          })
+        );
         return false;
       } else {
         return true;

config/locales/client.en.yml

@@ -2093,7 +2093,7 @@ en:
         upload: "Sorry, there was an error uploading that file. Please try again."
         file_too_large: "Sorry, that file is too big (maximum size is {{max_size_kb}}kb). Why not upload your large file to a cloud sharing service, then share the link?"
         too_many_uploads: "Sorry, you can only upload one file at a time."
-        too_many_dragged_and_dropped_files: "Sorry, you can only upload 10 files at a time."
+        too_many_dragged_and_dropped_files: "Sorry, you can only upload {{max}} files at a time."
         upload_not_authorized: "Sorry, the file you are trying to upload is not authorized (authorized extensions: {{authorized_extensions}})."
         image_upload_not_allowed_for_new_user: "Sorry, new users can not upload images."
         attachment_upload_not_allowed_for_new_user: "Sorry, new users can not upload attachments."

config/locales/server.en.yml

@@ -1470,6 +1470,8 @@ en:
 
     min_ratio_to_crop: "Ratio used to crop tall images. Enter the result of width / height."
 
+    simultaneous_uploads: "Maximum number of files that can be dragged & dropped in the composer"
+
     enable_flash_video_onebox: "Enable embedding of swf and flv (Adobe Flash) links in oneboxes. WARNING: may introduce security risks."
 
     default_invitee_trust_level: "Default trust level (0-4) for invited users."

config/site_settings.yml

@@ -1031,6 +1031,11 @@ files:
     default: 0.45 # 90% of 18:9
     min: 0
     max: 1
+  simultaneous_uploads:
+    client: true
+    default: 5
+    min: 0
+    max: 20
 
 trust:
   default_trust_level: