Get model from mongoose db - node.js

Question

I'm currently looking into building a small REST based service to which I can POST some data into a mongoose db and GET the data back.
Here's my main.js file:
var http = require("http");
var DAO = require("./DAO");
var express = require("express");
var util = require('util');
var app = express();
app.use(express.bodyParser());
app.post('/postIsles',function(req,res){
DAO[req.method](req.body);
res.send("body" + req.body.name);
});
app.get('/getIsles',function(req,res){
var isleVar = DAO[req.method](req);
res.send(isleVar);
});
app.listen("3000");
console.log("\nApp available at http://127.0.0.1:3000\n");
And DAO.js:
var mongoose = require('mongoose');
//Connect to database
mongoose.connect( 'mongodb://127.0.0.1:27017/library_database' );
//Schemas
var Isle = new mongoose.Schema({
name: String,
description: String,
lastStocked: Date
});
//Models
var IsleModel = mongoose.model( 'Isle', Isle );
function POST(request) {
var name = request.name;
var description = request.description;
var lastStocked = request.lastStocked;
console.log("POST REQ +" + request);
var isle = new IsleModel({
name: name,
description: description,
lastStocked: lastStocked
});
isle.save( function( err ) {
if( !err ) {
return console.log( 'created' );
} else {
return console.log( err );
}
});
}
function GET(request) {
return IsleModel.find( function( err, islesT ) {
if( !err ) {
console.log("isles :"+islesT);
return islesT;
} else {
return console.log( err );
}
});
}
exports.POST = POST;
exports.GET = GET;
When I try to run the GET, I get the following error:
TypeError: Converting circular structure to JSON
at Object.stringify (native)
I'm a bit unsure how to overcome this.

Answer 1

Remember when using Node.js: any operation that involves IO will be asynchronous.
Model#find is an asynchronous method, so isleVar is not set to the result you're expecting. Your result will only be available inside of the anonymous function that you pass into IsleModel.find
To fix your GET method, you'll need to modify your code to take into account the asynchronicity of the DB request and only send the response once your app has had a chance to retrieve data.
Below, is an example of one possible solution to fix /getIsles:
In main.js, modify your get route to pass in res (so it can be handled asynchronously)
app.get('/getIsles',function(req,res){
return DAO[req.method](req, res);
});
In DAO.js, have response send the data inside of your callback to IsleModel.find
function GET(request, response) {
IsleModel.find( function( err, islesT ) {
if( !err ) {
console.log("isles :"+islesT);
response.send(islesT);
} else {
return console.log( err );
}
});
}