try to speak mangoose

backend/routes/routesToucan.js

@@ -10,19 +10,19 @@ var upload = require("../utils/fileSaver");
 var Toucan = require("../models/modelToucan");
 var router = express.Router();
 
-let urltoucans = Toucan.aggregate
-    .addFields({titlelc: {$split: [{$toLower:"$title"}, " "]}})
-    .addFields({year:{$dateToString: {format: "%Y", date: "$date"}}})
-    .$addFields(
+const urltoucans = Toucan.aggregate([
+    {$addFields: {titlelc: {$split: [{$toLower:"$title"}, " "]}}}, 
+    {$addFields:{year:{$dateToString: {format: "%Y", date: "$date"}}}}, 
+    {$addFields:
         {titlelcnospace:  
             {$reduce: 
                 {input: "$titlelc",initialValue: "",
-                in: { $concat : ["$$value", "$$this"]}}}})
-    .addFields(
+                in: { $concat : ["$$value", "$$this"]}}} }}, 
+    {$addFields:
         {urlId:
-            {$concat:["$titlelcnospace","-","$year"]}})
-    .unset(["titlelc","year","titlelcnospace","title","date"]) 
-;
+            {$concat:["$titlelcnospace","-","$year"]}}}, 
+    {$unset:["titlelc","year","titlelcnospace","title","date"]}, 
+]);
 
 router.route("/toucans")
 /**
@@ -156,7 +156,13 @@ router.route("/img/:id")
 
     router.get('/pdf/urlID', (req, res) => {
         try {  
-              res.json(urltoucans);
+              urltoucans.exec((err,data) => {
+                if (err) {
+                  console.log(err);
+                  
+                } else {
+                  res.send(data);
+              }});
             } catch (err) {
               console.log(err);
               res.sendStatus(401);