Only show file templates which are available for the selected file type

app/assets/javascripts/exercises.js

@@ -148,6 +148,22 @@ $(function() {
     });
   };
 
+  var updateFileTemplates = function(fileType) {
+      var jqxhr = $.ajax({
+          url: '/file_templates/by_file_type/' + fileType + '.json',
+          dataType: 'json'
+      });
+      jqxhr.done(function(response) {
+          var noTemplateLabel = $('#noTemplateLabel').data('text');
+          var options = "<option value>" + noTemplateLabel + "</option>";
+          for (var i = 0; i < response.length; i++) {
+              options += "<option value='" + response[i].id + "'>" + response[i].name + "</option>"
+          }
+          $("#code_ocean_file_file_template_id").find('option').remove().end().append($(options));
+      });
+      jqxhr.fail(ajaxError);
+  }
+
   if ($.isController('exercises')) {
     if ($('table').isPresent()) {
       enableBatchUpdate();
@@ -162,6 +178,10 @@ $(function() {
       inferFileAttributes();
       observeFileRoleChanges();
       overrideTextareaTabBehavior();
+    } else if ($('#files.jstree').isPresent()) {
+        var fileTypeSelect = $('#code_ocean_file_file_type_id');
+        fileTypeSelect.on("change", function() {updateFileTemplates(fileTypeSelect.val())});
+        updateFileTemplates(fileTypeSelect.val());
     }
     toggleCodeHeight();
     if (window.hljs) {

app/controllers/file_templates_controller.rb

@@ -6,6 +6,14 @@ class FileTemplatesController < ApplicationController
   end
   private :authorize!
 
+  def by_file_type
+    @file_templates = FileTemplate.where(:file_type_id => params[:file_type_id])
+    authorize!
+    respond_to do |format|
+      format.json { render :show, status: :ok, json: @file_templates.to_json }
+    end
+  end
+
   # GET /file_templates
   # GET /file_templates.json
   def index

app/policies/file_template_policy.rb

@@ -4,4 +4,8 @@ class FileTemplatePolicy < AdminOnlyPolicy
     everyone
   end
 
+  def by_file_type?
+    everyone
+  end
+
 end

app/views/code_ocean/files/_form.html.slim

@@ -12,4 +12,5 @@
     = f.label(:file_template_id, t('activerecord.attributes.file.file_template_id'))
     = f.collection_select(:file_template_id, FileTemplate.all.order(:name), :id, :name, {:include_blank => true}, class: 'form-control')
   = f.hidden_field(:context_id)
+  .hidden#noTemplateLabel data-text=t('file_template.no_template_label')
   .actions = render('shared/submit_button', f: f, object: CodeOcean::File.new)