added new pet. remove pet breaks dont know why

backend/app/index.js

@@ -16,6 +16,14 @@ app.use(cors())
 
 var people_path = '/people'
 
+function end(res,err) {
+  if (err) {
+    return res.status(500).send(err)
+  }else{
+    res.send("ok")
+  }
+}
+
 app.get(people_path,function (req,res) {
   people.index(function (err,people) {
     res.send(people)
@@ -24,20 +32,32 @@ app.get(people_path,function (req,res) {
 
 app.post(people_path,function (req,res) {
   var person_name = req.body.name
-  people.create(person_name,function (err) {
-    res.send(err)
+  people.create(person_name, function (err) {
+    end(res,err)
   })
 })
 
 app.put(people_path+"/:person_id",function (req,res) {
-  people.modify(req.params.person_id,req.body.name, function (err) {
-    res.send(err)
+  people.modify(req.params.person_id,req.body.name,  function (err) {
+    end(res,err)
   })
 })
 
 app.delete(people_path+"/:person_id",function (req,res) {
-  people.remove(req.params.person_id, function (err) {
-    res.send(err)
+  people.remove(req.params.person_id,  function (err) {
+    end(res,err)
+  })
+})
+
+app.post(people_path+"/pets",function (req,res) {
+  people.addPet(req.body.id,req.body.petname, function (err) {
+    end(res,err)
+  })
+})
+
+app.delete(people_path+"/pets",function (req,res) {
+  people.removePet(req.body.id,req.body.petname, function (err) {
+    end(res,err)
   })
 })
 

backend/app/people/people.js

@@ -4,10 +4,10 @@ var mongoose = require('mongoose')
 var people = {}
 
 db.once('open',function () {
-  people.model = mongoose.model('People',{ name: String })
+  people.model = mongoose.model('People',{ name: String, pets: Array })
 
   people.index = function (callback) {
-    people.model.find({},'name',callback)
+    people.model.find({},callback)
   }
 
   people.create = function (personName, callback) {
@@ -26,6 +26,20 @@ db.once('open',function () {
     people.model.findById(id).remove(callback)
   }
 
+  people.addPet = function (id,pet_name,callback) {
+    people.model.findById(id).then(function (person) {
+      person.pets.push(pet_name)
+      person.save(callback)
+    })
+  }
+
+  people.removePet = function (id, pet_name , callback) {
+    people.model.findById(id).then(function (person) {
+      person.pets.remove(pet_name)
+      person.save(callback)
+    })
+  }
+
 })
 
 module.exports = people