I've been building my first node.js app using express.js.
It has been fun :)
I must be having some kind of misconception going, so here goes.
I have some route defined as such:
app.all('/account/summary', apiPOST('AccountSummary', {FromDate: 'default', ToDate: 'default'}), function(req, res){
var data=req.apiJSON;
console.log(data);
res.render('accountsummary', {locals: data, layout: 'layouts/layout'});
});
apiPOST() is defined as such:
apiPOST = function (operation, postParams) {
return function (req, res, next){
console.log('RIGHT AT START');
console.log(postParams);
console.log('END');
var currentDate = new Date();
var day = ('0'+currentDate.getDate()).slice(-2);
var month = ('0'+(currentDate.getMonth() + 1)).slice(-2);
var year = ('0'+currentDate.getFullYear()).slice(-4);
console.log('BEFORE DATES');
console.log(postParams);
if (typeof(postParams.FromDate)!='undefined' && (postParams.FromDate=='default' || postParams.FromDate=='')){
postParams.FromDate=year+'-'+month+'-'+day;
}
if (typeof(postParams.ToDate)!='undefined' && (postParams.ToDate=='default' || postParams.ToDate=='')){
postParams.ToDate=year+'-'+month+'-'+day;
}
//automatically add all posted data to postParams
if (typeof(req.body)!='undefined'){
for (var key in req.body){
if (req.body.hasOwnProperty(key)){
postParams[key]=req.body[key];
}
}
}
// here is do some talking to an XML web service and convert it to JSON;
// we use our postParams variable to POST
next();
}
}
First off this works fine. When reaching the page on a GET request, it defaults both FromDate and ToDate to today. This page has a form that you may post to specify a new FromData and ToDate. the posted data automatically get added to the postParams and that also works fine.
The problem that I am experiencing is that the next time a user visits the page using GET, the previously POSTed data is still around and so it default to that and not to today.
I cannot figure out why that data is still available. By the looks of it, it is not being posted, but rather remembered in postParams. Is postParams now global?
Thanks!
What's happening is that you're calling apiPOST only once, during the app.all call to configure that route and that one call creates the one postParams parameter object that all future invocations of apiPOST's returned function will share.
Related
I am working on building a blog API for a practice project, but am using the data from an external API. (There is no authorization required, I am using the JSON data at permission of the developer)
The idea is that the user can enter multiple topic parameters into my API. Then, I make individual requests to the external API for the requested info.
For each topic query, I would like to:
Get the appropriate data from the external API based on the params entered (using a GET request to the URL)
Add the response data to my own array that will be displayed at the end.
Check if each object already exists in the array (to avoid duplicates).
res.send the array.
My main problem I think has to do with understanding the scope and also promises in Axios. I have tried to read up on the concept of promise based requests but I can't seem to understand how to apply this to my code.
I know my code is an overall mess, but if anybody could explain how I can extract the data from the Axios function, I think it could help me get the ball rolling again.
Sorry if this is a super low-level or obvious question - I am self-taught and am still very much a newbie!~ (my code is a pretty big mess right now haha)
Here is a screenshot of the bit of code I need to fix:
router.get('/:tagQuery', function(req, res){
const tagString = req.params.tagQuery;
const tagArray = tagString.split(',');
router.get('/:tag', function(req, res){
const tagString = req.params.tag;
const tagArray = queryString.split(',');
const displayPosts = tagArray.map(function(topic){
const baseUrl = "https://info.io/api/blog/posts";
return axios
.get(baseUrl, {
params: {
tag: tag
}
})
.then(function(response) {
const responseData = response.data.posts;
if (tag === (tagArray[0])){
const responseData = response.data.posts;
displayPosts.push(responseData);
} else {
responseData.forEach(function(post){
// I will write function to check if post already exists in responseData array. Else, add to array
}); // End if/then
})
.catch(function(err) {
console.log(err.message);
}); // End Axios
}); // End Map Function
res.send(displayPosts);
});
Node.js is a single thread non-blocking, and according to your code you will respond with the result before you fetching the data.
you are using .map which will fetch n queries.
use Promise.all to fetch all the requests || Promise.allsettled.
after that inside the .then of Promise.all || promise.allsettled, map your result.
after that respond with the mapped data to the user
router.get('/:tag', function (req, res) {
const tagString = req.params.tag;
const tagArray = queryString.split(',');
const baseUrl = "https://info.io/api/blog/posts";
const topicsPromises=tagArray.map((tobic)=>{
return axios
.get(baseUrl, {
params: {
tag: tag
}
})
});
Promise.all(topicsPromises).then(topicsArr=>{
//all the data have been fetched successfully
// loop through the array and handle your business logic for each topic
//send the required data to the user using res.send()
}).catch(err=>{
// error while fetching the data
});
});
your code will be something like this.
note: read first in promise.all and how it is working.
I am building an API to manage meetups with nodeJS. I have build an endpoint with the route "/meetups/:id/" to fetch a specific meetup record by its id. And then I want to fetch all the upcoming meetup records and I tried to use "/meetups/upcoming/" but when I query it, I get the not found error (404). It seems like the second route is not recognised.
Here is the code defining the two routes
the request from postman
Any help on how can I handle that?
Thanks.
Route is '/api/v1/meetups/upcoming/all'. Move res.status outside the map function.
EDIT: you'll have to change the route which has to be different from api/v1/meetups/:id. Reason is when route '/api/v1/meetups/upcoming' is requested express sees it as the same route as before and takes 'upcoming' as the parameter.
app.get("/api/v1/meetups/upcoming/all", function(req, res) {
var today = new Date();
var upcomings = db.meetups.map(function(meetup) {
if(meetup.happeningOn > today) {
return meetup;
}
});
res.status(200).send({
status: 200,
data: upcomings
});
});
You need to move the res.status piece outside of the const upcomings definition.
I'm trying to write a simple Swagger API that will allow me to sync a couple of systems on demand. The syncing is one way, so basically the end goal will be to send a request to both system, see what's new/changed/removed on the origin, then update the destination. I've been trying to do this using node.js instead of Java, to which I'm more used to, as a learning experience, but I'm really having a hard time figuring out a key issue due to the async nature.
As a test, I constructed a simple Express node.js app on IntelliJ, where in one of the routes I'm calling a function exported from a different file and trying to get the response back. Unfortunately, this isn't working so well. What I've done is this:
getit.js - (this goes to the Ron Swanson generator to get a quote)
const rp = require('request-promise');
async function dorequest() {
const response = await rp(uri);
return Promise.resolve(response);
};
module.exports = {dorequest}
In the route I've done this:
var getit = require ('./getit.js');
/* GET users listing. */
router.get('/', function(req, res, next) {
var ret = getit.dorequest();
res.send(ret);
console.log('res out' + ret);
});
What I get in the console is
res out[object Promise]
and the response is of course empty.
What am I doing wrong? I've been playing with this for a week now, tried various methods, but I keep getting similar results. I'm obviously missing something out, and would appreciate some help.
Thanks!
Object is empty because it was written on the console before the Promise is resolved. You have to wait until Promise is resolved and then send the response back so try to change your code like this:
var getit = require ('./getit.js');
/* GET users listing. */
router.get('/', function(req, res, next) {
getit.dorequest().then(function(data) {
console.log('res out' + data);
res.send(data);
});
});
Since you are using async/await approach all you need to do is to place await before getit.dorequest();
so this line will look like var ret = await getit.dorequest();
I have just begun to learn node.js. Over the last two days, I've been working on a project that accepts userinput and publishes a ICS file. I have all of that working. Now consider when I have to show this data. I get a router.get to see if I am at the /cal page and..
router.get('/cal', function(req, res, next)
{
var db = req.db;
var ical = new icalendar.iCalendar();
db.find({
evauthor: 'mykey'
}, function(err, docs) {
docs.forEach(function(obj) {
var event2 = ical.addComponent('VEVENT');
event2.setSummary(obj.evics.evtitle);
event2.setDate(new Date(obj.evics.evdatestart), new Date(obj.evics.evdateend));
event2.setLocation(obj.evics.evlocation)
//console.log(ical.toString());
});
});
res.send(ical.toString());
// res.render('index', {
// title: 'Cal View'
// })
})
So when /cal is requested, it loops through my db and creates an ICS calendar ical. If I do console.log(ical.toString) within the loop, it gives me a properly formatted calendar following the protocol.
However, I'd like to END the response with this. At the end I do a res.send just to see what gets published on the page. This is what gets published
BEGIN:VCALENDAR VERSION:2.0
PRODID:calendar//EN
END:VCALENDAR
Now the reason is pretty obvious. Its the nature of node.js. The response gets sent to the browser before the callback function finishes adding each individual VEVENT to the calendar object.
I have two related questions:
1) Whats the proper way to "wait" till the callback is done.
2) How
do I use res to send out a .ics dynamic link with
ical.toString() as the content. Do I need to create a new view for
this ?
edit: I guess for number 2 I'd have to set the HTTP headers like so
//set correct content-type-header
header('Content-type: text/calendar; charset=utf-8');
header('Content-Disposition: inline; filename=calendar.ics');
but how do I do this when using views.
Simply send the response, once you got the neccessary data! You are not required to end or send directly in your route but can do it in a nested callback as well:
router.get('/cal', function(req, res, next) {
var db = req.db;
var ical = new icalendar.iCalendar();
db.find({
evauthor: 'mykey'
}, function(err, docs) {
docs.forEach(function(obj) {
var event2 = ical.addComponent('VEVENT');
event2.setSummary(obj.evics.evtitle);
event2.setDate(new Date(obj.evics.evdatestart), new Date(obj.evics.evdateend));
event2.setLocation(obj.evics.evlocation)
});
res.type('ics');
res.send(ical.toString());
});
});
I also included sending the proper Content-Type by using res.type.
Also: Don't forget to add proper error handling. You can for example use res.sendStatus(500) if an error occured while retrieving the documents.
I have this route that queries an API to get information about the project. It uses super agent to post a get request, passes along some headers with the .set and project_results should contain the data.
Now here is the issue: I can load the page for this particular route/project 20 times... 19 of the times it will work perfectly but randomly it will throw an error:
TypeError: Cannot read property 'creator' of null
This error points out the line: with if(project.creator == req.signedCookies.user_3rb._id) {
So I know it is making it past the: if(project_results.status == '200') {
and since I am looking at the same project over and over and over (and I know all projects have a creator I checked the DB)
my question would be why sometimes does it not find this property of the project_results variable? Its very inconsistent.. I would think project_results is completely populated before going through the code... since its passing the status check we know there is at least some data in the project_results variable..
app.get('/user/projects/:project_id', function(req, res, next) {
var agent = superagent.agent();
var project = {};
project.id = req.params.project_id;
agent
.get(apihost + '/api/project/'+project.id)
.set('api_key', apikey)
.set('access_token', user.access_token)
.end(function(project_error, project_results) {
if (project_error) {
console.log(project_error);
}
if(project_results.status == '200') {
project = JSON.parse(project_results.text);
// Check if we are the owner of the project
if(project.creator == req.signedCookies.user_3rb._id) {
project.owner = true;
}
......
I'm one of the contributors to superagent.
I'd recommend isolating a test case instead of trying to debug directly in your app.
One simple way is to create a very short express app that always returns a hardcoded, perfect response to the route you're trying to reach - then see if project is still null 1 in 20 times:
var app = express();
app.use(function(req, res, next) {
res.send({
// your data hardcoded here
});
});
app.listen(3000);
If it's still null 1 in 20 times, then please submit it as an issue and I'll check it out. If not, then likely something else is going on - perhaps the data isn't being consistently fetched from the db, or there's a race condition between the fetch and the rendering.