I have a simple node+express app that makes a few async http/get url requests if you visit a certain page. This is to simply get some data from the db, and send that to the view. The routes are handled using a standard separate routes.js file.
routes.js
...
const bluebird = require('bluebird');
const promiseRequest = bluebird.promisify(require('request'));
Promise.all([
promiseRequest(`http://url1...`),
promiseRequest(`http://url2...`)
])
.then((promiseRes) => {
res.render(...); // loads the view for the client
})
.catch((err) => {
errorHandler(err, req, res); // to be handled by express middleware
});
The http url requests are handled using a controller file, which makes a query to the db, and returns either the values or an error.
controller.js
try {
const {rows, rowCount} = await db.query(findAllQuery);
return res.status(200).send({rows, rowCount});
} catch (error) {
return res.status(400).send({
"name": error.name,
"psql_error_code": error.code
});
}
The controller is working fine, but I am purposely typing in a wrong get url so that the controller returns the res.status(400)... object back to the route. No matter what I return to the route, the promise resolves. I even tried returning a new Error('Error description'), but the promisify receives this as a resolution.
Any help would be deeply appreciated!
--
The response from the controller to the route is a lengthy object.
As I can not see how you have implemented errorHandler(). One thing I can think of that you should look for is that - if inside .catch(err){} of the called promise you are not returning any error, it will go to the then of the calling function.
Related
I'm having problems when I deploy my alexa skill to google cloud functions.
Initially, I'm using the following code.
My skill.js file
//imports here...
Router.post("/:locale", async (req, res) => {
const requestEnvelope = JSON.stringify(req.body);
try {
await new SkillRequestSignatureVerifier().verify(requestEnvelope, req.headers);
await new TimestampVerifier().verify(requestEnvelope);
} catch (err) {
console.log(`Error with message: ${err.message}`);
console.log(`Error object: ${JSON.stringify(err)}`);
return res.status(400).send(err.message);
}
const responseASK = await skill.invoke(req.body);
return res.status(200).send(responseASK);
});
module.exports = Router;
In my server.js file
const skillRoute = require("./skill");
const express = require("express");
const server = express();
server.use("/", skillRoute);
exports.server = functions.https.onRequest(server);
Everything goes well with the deploy, including, I can invoke my alexa skill normally. But, when running the validations for distribution, I get the following problem:
The skill is rejecting the request when executed with additional properties in the JSON request.
When we invoke the skill with additional parameters, the skill is rejecting it when we expect this to be accepted. Future versions of the Alexa Skills Kit may add new properties to the JSON request and response formats, while maintaining backward compatibility for the existing properties. Your code must be resilient to these types of changes. For example, your code for de-serializing a JSON request must not break when it encounters a new, unknown property. Please ensure that your code can handle new attributes and does not break when it encounters new properties in the JSON request.
Documentation Help:
Request and response JSON reference: Click here
On my server console I get the following errors:
Error with message: request body and signature does not match
and:
Error object: {"name":"AskSdk.SkillRequestSignatureVerifier Error"}
It seems to me that it may be the result of some ask-sdk-core update, as I have other servers working with the same code.
I'm trying to pass a variable to EJS a second time in my code and am running into trouble. Here is my code:
axios.get(yearURL)
.then(function (res) {
let data = res.data.MRData.SeasonTable.Seasons;
years = data.map(d => d.season);
app.get('/', function (req, res) {
res.render('index.ejs', {
years: years
});
app.post('/down', function(req, res) {
let year = req.body;
res.redirect('/');
axios.get(`http://ergast.com/api/f1/${year.year}/drivers.json`)
.then(function (res) {
let data = res.data.MRData.DriverTable.Drivers;
drivers = data.map(d => `${d.givenName} ${d.familyName}`);
})
.catch(function (err) {
console.log(err);
})
res.render('index.ejs', {
drivers: drivers,
years: years
});
Whenever I run this however, I receive an error that I cannot set headers after they are sent to the client. I've also read elsewhere that apparently you can not call res.render twice. So my question is, how can I pass another set of data to EJS after I have already called res.render once before?
Here it is as pseudocode. It's good to start your program with this level of logical structure, and then implement it:
Define ready = false, errored = false, and data = undefined
variables.
Get the data from the remote API, in the then branch, set
ready = true, assign result to data. In the error branch, set errored
= true. Should we retry on error?
Define the / GET route.
If not ready, check errored. If not errored, we are still waiting for the data. In this case, do we wait for the call to resolve, or return something to the client to let them know?
If not ready, and errored, tell the client that there was an error.
If ready == true, then we have data to render a response to the client.
Define the /down route. It needs to take a year parameter, and we need to make an async call in the route handler to get the data.
Can we cache the data, so that subsequent calls for the same year return data that we fetched previously? If we can, use an object as a lookup dictionary. If the object has a key for that year, use the cached data to render the response. If not, make the call, and in the then branch, add the response to the cache object, and use the data to render the response.
I am experimenting with t library, and am trying to install the functionality into my own search bar to practice (still a student).
Can anyone provide advice to the format this would be in??
#PascalLamers answer is the cleanest way to go about it, using the "await" pattern.
To see what this looks like with promise chaining:
app.get('/:url', async function (req, res) {
return wappalyzer
.init()
.then(function(){
return wappalyzer.open(decodeURIComponent(req.params.url))
})
.then(function(site){
return site.analyze()
})
.then(function(data){
return res.status(200).json(data);
})
.catch(function(err){
return res.status(500).json({ message : err.message })
})
}
Each then executes a single async operation, and on success passes its result to the next then() operation.
Each then() is only called upon the success of the previous then(). If an error occurs at any point, the catch() is executed and the function returns (in this case, returns an error 500).
Completely ignoring what wappalyzer actually is or does, I would suggest the following, since you are already providing an async function as callback to your route controller :
app.get('/:url', async function (req, res) {
try {
await wappalyzer.init();
const site = await wappalyzer.open(decodeURIComponent(req.query.url));
const data = await site.analyze();
// if you end up here, everything was successfull
return res.status(200).json(data);
} catch (ex) {
// if you end up here, something went wrong
return res.status(500).json({ message : ex.message });
}
});
The above doesn't really make much sense, since you are telling your backend to look for an url param but using a query parameter instead. I woudln't recommend to send an url as either, param or query. Use the request body instead :
// receive request in backend, with an endpoint that makes a bit more sense
// also using POST method, otherwise you won't be able to send a body
app.post('/search', async function (req, res) {
const url = req.body.url;
// do stuff
});
// sending request to backend, using axios for example
const respond = await axios.post('/search', { url : 'www.google.com' });
// or using fetch
const respond = await fetch('/search', {
method: 'post',
body: JSON.stringify({ url : 'www.google.com' });
Please be aware these are just pointers, nothing to copy & paste :) .
If you are using Express, I suggest reading the documentation again. I think you are misunderstanding how the router works : https://expressjs.com/de/guide/routing.html#route-parameters
The Nodejs functions return an error from try/catch scope, such as the one below if the user doesn't exist of if a database is not reachable:
router.delete('/delete/:email', async (req, res) => {
var email = req.params.email;
try {
let result = await User.remove({"email": email});
res.status(204).send(email);
} catch (err) {
res.status(400).send(err);
}
});
I can also return the Error from Nodejs server by myself:
return res.status(400).send(new Error(`The user with email ${email} doesn't exist.`));
The first problem is that I can't find the error message that is embedded somewhere deep in the body the returned Error object. It is stored in one of its 100+ attributes. Where should I look for it so I could display in on a screen for the end user to read it?
Then, the err object generated by the try/catch scope has a set of different attributes comparing to the Error object created with new Error("Here is my error message"). Is there a way to normalize the returned Errors so they all have the same or similar attributes?
You don't need to return the whole error object from the server, and arguably shouldn't since error messages can expose internals about your code and infrastructure.
One way you could handle this is to format and return an error message from the server yourself. Assuming you're using express this would look something like:
return res.status(400).json({ message: `The user with email ${email} doesn't exist.` });
Alternatively you could use an error handling middleware like strong-error-handler found here: https://github.com/strongloop/strong-error-handler which automatically builds a json formatted message that's easier to parse, but keep in mind that the content of the message differs depending on whether you set debug mode to true or no.
If you want to develop a secure web application with nice error handling, i will suggest you the following structure.
Step 1. At front end divide your api calls in four main operations for e.g. inset,update,query and filter.
now whenever your page loads and you want to show some data fetched from server then your api call must be like 'https://domainname.tld/server/query' and send some payload with this api call according to need of your data requirements to be fetched.
At backend probably at Server.js handle like this :
app.all("/server/query", function (req, res) {
try {
console.log(a);
// some database or io blocking process
} catch (error) {
// error handling
var err = writeCustomError(error.message || error.errmsg || error.stack);
res.status(417).json(err).end();
}
});
function writeCustomError(message) {
var errorObject = {};
errorObject.message = message;
errorObject.code = 10001; // as you want
errorObject.status = "failed";
return errorObject;
}
in try block you can also handle logical errors using same function i.e writeCustomError
So if you use this approach you can also implement end-to-end encryption and send only eP('encrypted payload') and eK('encryption Key'),by doing this end users and bad end users even can not evaluate your serve API calls.
If you are thinking how will you route different paths at server then simplest solution is send uri in payload from client to server for e.g
User wants to reset password :-
then
call api like this
https://domain.tld/server/execute and send Json object in payload like this {uri:"reset-password",old:"",new:""}.
at backend
use
app.all("/server/execute", function (req, res) {
try {
// decrypt payload
req.url = payload.uri;
next();
} catch (error) {
// error handling
var err = writeCustomError(error.message || error.errmsg || error.stack);
res.status(417).json(err).end();
}
});
app.all("/reset-password", function (req, res) {
try {
// reset logic
} catch (error) {
// error handling
var err = writeCustomError(error.message || error.errmsg || error.stack);
res.status(417).json(err).end();
}
});
so in this way only developer know where password reset logic and how it can called and what parameters are required.
I will also suggest you to create different router files for express like QueryRouter,InsertRouter etc.
Also try to implement end-to-end encryption.Any query regarding post,kindly comment it.
So i've been doing some reading and I think I have a general grasp on this subject but could use some insight from someone more experienced. I've been trying to write a simple RSS reader in Meteor and have been facing some issues with calling the Meteor method asynchronously. I currently define the method on the server(synchronously) and call it on the client(asynchronously). What I don't understand is that when I try to make the HTTP.call on the server, I return an undefined value passed to my client if I pass a callback into the request. But when I make the API request synchronously everything seems to work fine. Is this the normal behavior I should expect/the way I should be making the API call?
Meteor.methods({
getSubReddit(subreddit) {
this.unblock();
const url = 'http://www.reddit.com/r/' + subreddit + '/.rss';
const response = HTTP.get(url, {}, (err, res) => {
if(!err) {
//console.log(res.content);
return res;
} else {
return err;
}
});
}
});
Here's the method defined on the server side. Note that logging res.content shows that I'm actually getting the right content back from the call. I've tried reading some other answers on the topic and seen some things about using Future/wrapAsync, but I'm not sure I get it. Any help would be greatly appreciated!
The HTTP.get is doing async work, so callback passed to it will be called out of this meteor method call context.
To get desired result you should do it like this:
Meteor.methods({
getSubReddit(subreddit) {
// IMPORTANT: unblock methods call queue
this.unblock();
const url = 'http://www.reddit.com/r/' + subreddit + '/.rss';
const httpGetSync = Meteor.wrapAsync(HTTP.get);
try {
const response = httpGetSync(url, {});
//console.log(response.content);
return response.content;
} catch (err) {
// pass error to client
throw new Meteor.Error(...);
}
}
});