Disable mustache render where there is nothing to render

Converting the entire HTML to a mustache template where there is no data passed uses a huge amount of memory to do a no-op.

Skip the mustache rendering if no data is passed.

middleware/render.js

@@ -7,6 +7,10 @@ module.exports = (req, res, next) => {
   req.log('debug', 'Rendering HTML');
   const template = req.body.template;
   const data = req.body.data;
+  if (!data || req.body.noRender) {
+    res.locals.html = template;
+    return next();
+  }
   try {
     debug('Rendering %s', template);
     const rendered = mustache.render(template, data);

middleware/validate.js

@@ -5,6 +5,9 @@ const debug = require('debug')('pdf:middleware:validate');
 const ValidationError = require('../lib/validation-error');
 
 module.exports = (req, res, next) => {
+  if (req.body.noRender) {
+    return next();
+  }
   req.log('debug', 'Validating request');
   const template = req.body.template;
   let missing;

test/integration/index.js

@@ -106,13 +106,13 @@ describe('POSTing to /convert', () => {
 
   describe('with a valid html string', () => {
 
-    it('renders the html', () => {
+    it('renders the html without calling a mustache render', () => {
       return supertest(App)
         .post('/convert')
         .send({template: template})
         .expect(201)
         .expect('Content-type', /octet-stream/)
-        .expect(() => assert(mustache.render.calledOnce));
+        .expect(() => assert(!mustache.render.called));
     });
 
     it('returns a 201 and a PDF', () => {