Customize Loopback response after save - json

I have a loopback 2.x app, in which I have a model Conversation and a model Message, with a relationship "Conversation has many messages". I want to customize the response for POST conversations/:id/messages with a json response different than the default, say {status: 'success'}. I tried to use remote hook for the method __create__messages, but it did not work:
Conversation.afterRemote('__create__messages', function(ctx, next) {
ctx.result.data = {
success: 'yes'
};
next();
});
This still returns the default response. How can I return a custom json for a remote method? I have seen examples only for all models, or for all methods: multiple models, multiple methods

Maybe you can try a version of following code below. Also, I think you are meaning to to manipulate data before the method finishes, not after. If you wait, the response will already be created, preventing your intended goal. Let me know if this works (replace with methods that will work for your use case).
Conversation.observe('before save', function(context, next) {
var instance = context.instance || context.data;
if (!instance) return next();
// Your code here
next();
});

Related

How to get around previously declared json body-parser in Nodebb?

I am writing a private plugin for nodebb (open forum software). In the nodebb's webserver.js file there is a line that seems to be hogging all incoming json data.
app.use(bodyParser.json(jsonOpts));
I am trying to convert all incoming json data for one of my end-points into raw data. However the challenge is I cannot remove or modify the line above.
The following code works ONLY if I temporarily remove the line above.
var rawBodySaver = function (req, res, buf, encoding) {
if (buf && buf.length) {
req.rawBody = buf.toString(encoding || 'utf8');
}
}
app.use(bodyParser.json({ verify: rawBodySaver }));
However as soon as I put the app.use(bodyParser.json(jsonOpts)); middleware back into the webserver.js file it stops working. So it seems like body-parser only processes the first parser that matches the incoming data type and then skips all the rest?
How can I get around that? I could not find any information in their official documentation.
Any help is greatly appreciated.
** Update **
The problem I am trying to solve is to correctly handle an incoming stripe webhook event. In the official stripe documentation they suggested I do the following:
// Match the raw body to content type application/json
app.post('/webhook', bodyParser.raw({type: 'application/json'}),
(request, response) => {
const sig = request.headers['stripe-signature'];
let event;
try {
event = stripe.webhooks.constructEvent(request.body, sig,
endpointSecret);
} catch (err) {
return response.status(400).send(Webhook Error:
${err.message});
}
Both methods, the original at the top of this post and the official stripe recommended way, construct the stripe event correctly but only if I remove the middleware in webserver. So my understanding now is that you cannot have multiple middleware to handle the same incoming data. I don't have much wiggle room when it comes to the first middleware except for being able to modify the argument (jsonOpts) that is being passed to it and comes from a .json file. I tried adding a verify field but I couldn't figure out how to add a function as its value. I hope this makes sense and sorry for not stating what problem I am trying to solve initially.
The only solution I can find without modifying the NodeBB code is to insert your middleware in a convenient hook (that will be later than you want) and then hack into the layer list in the app router to move that middleware earlier in the app layer list to get it in front of the things you want to be in front of.
This is a hack so if Express changes their internal implementation at some future time, then this could break. But, if they ever changed this part of the implementation, it would likely only be in a major revision (as in Express 4 ==> Express 5) and you could just adapt the code to fit the new scheme or perhaps NodeBB will have given you an appropriate hook by then.
The basic concept is as follows:
Get the router you need to modify. It appears it's the app router you want for NodeBB.
Insert your middleware/route as you normally would to allow Express to do all the normal setup for your middleware/route and insert it in the internal Layer list in the app router.
Then, reach into the list, take it off the end of the list (where it was just added) and insert it earlier in the list.
Figure out where to put it earlier in the list. You probably don't want it at the very start of the list because that would put it after some helpful system middleware that makes things like query parameter parsing work. So, the code looks for the first middleware that has a name we don't recognize from the built-in names we know and insert it right after that.
Here's the code for a function to insert your middleware.
function getAppRouter(app) {
// History:
// Express 4.x throws when accessing app.router and the router is on app._router
// But, the router is lazy initialized with app.lazyrouter()
// Express 5.x again supports app.router
// And, it handles the lazy construction of the router for you
let router;
try {
router = app.router; // Works for Express 5.x, Express 4.x will throw when accessing
} catch(e) {}
if (!router) {
// Express 4.x
if (typeof app.lazyrouter === "function") {
// make sure router has been created
app.lazyrouter();
}
router = app._router;
}
if (!router) {
throw new Error("Couldn't find app router");
}
return router;
}
// insert a method on the app router near the front of the list
function insertAppMethod(app, method, path, fn) {
let router = getAppRouter(app);
let stack = router.stack;
// allow function to be called with no path
// as insertAppMethod(app, metod, fn);
if (typeof path === "function") {
fn = path;
path = null;
}
// add the handler to the end of the list
if (path) {
app[method](path, fn);
} else {
app[method](fn);
}
// now remove it from the stack
let layerObj = stack.pop();
// now insert it near the front of the stack,
// but after a couple pre-built middleware's installed by Express itself
let skips = new Set(["query", "expressInit"]);
for (let i = 0; i < stack.length; i++) {
if (!skips.has(stack[i].name)) {
// insert it here before this item
stack.splice(i, 0, layerObj);
break;
}
}
}
You would then use this to insert your method like this from any NodeBB hook that provides you the app object sometime during startup. It will create your /webhook route handler and then insert it earlier in the layer list (before the other body-parser middleware).
let rawMiddleware = bodyParser.raw({type: 'application/json'});
insertAppMethod(app, 'post', '/webhook', (request, response, next) => {
rawMiddleware(request, response, (err) => {
if (err) {
next(err);
return;
}
const sig = request.headers['stripe-signature'];
let event;
try {
event = stripe.webhooks.constructEvent(request.body, sig, endpointSecret);
// you need to either call next() or send a response here
} catch (err) {
return response.status(400).send(`Webhook Error: ${err.message}`);
}
});
});
The bodyParser.json() middleware does the following:
Check the response type of an incoming request to see if it is application/json.
If it is that type, then read the body from the incoming stream to get all the data from the stream.
When it has all the data from the stream, parse it as JSON and put the result into req.body so follow-on request handlers can access the already-read and already-parsed data there.
Because it reads the data from the stream, there is no longer any more data in the stream. Unless it saves the raw data somewhere (I haven't looked to see if it does), then the original RAW data is gone - it's been read from the stream already. This is why you can't have multiple different middleware all trying to process the same request body. Whichever one goes first reads the data from the incoming stream and then the original data is no longer there in the stream.
To help you find a solution, we need to know what end-problem you're really trying to solve? You will not be able to have two middlewares both looking for the same content-type and both reading the request body. You could replace bodyParser.json() that does both what it does now and does something else for your purpose in the same middleware, but not in separate middleware.

How to parse or Stringify in asycnhronous way in javascript

I see that JSON.stringify and JSON.parse are both sycnhronous.
I would like to know if there a simple npm library that does this in an asynchonous way .
Thank you
You can make anything "asynchronous" by using Promises:
function asyncStringify(str) {
return new Promise((resolve, reject) => {
resolve(JSON.stringify(str));
});
}
Then you can use it like any other promise:
asyncStringfy(str).then(ajaxSubmit);
Note that because the code is not asynchronous, the promise will be resolved right away (there's no blocking operation on stringifying a JSON, it doesn't require any system call).
You can also use the async/await API if your platform supports it:
async function asyncStringify(str) {
return JSON.stringify(str);
}
Then you can use it the same way:
asyncStringfy(str).then(ajaxSubmit);
// or use the "await" API
const strJson = await asyncStringify(str);
ajaxSubmit(strJson);
Edited: One way of adding true asynchrnous parsing/stringifying (maybe because we're parsing something too complex) is to pass the job to another process (or service) and wait on the response.
You can do this in many ways (like creating a new service that shares a REST API), I will demonstrate here a way of doing this with message passing between processes:
First create a file that will take care of doing the parsing/stringifying. Call it async-json.js for the sake of the example:
// async-json.js
function stringify(value) {
return JSON.stringify(value);
}
function parse(value) {
return JSON.parse(value);
}
process.on('message', function(message) {
let result;
if (message.method === 'stringify') {
result = stringify(message.value)
} else if (message.method === 'parse') {
result = parse(message.value);
}
process.send({ callerId: message.callerId, returnValue: result });
});
All this process does is wait a message asking to stringify or parse a JSON and then respond with the right value.
Now, on your code, you can fork this script and send messages back and forward. Whenever a request is sent, you create a new promise, whenever a response comes back to that request, you can resolve the promise:
const fork = require('child_process').fork;
const asyncJson = fork(__dirname + '/async-json.js');
const callers = {};
asyncJson.on('message', function(response) {
callers[response.callerId].resolve(response.returnValue);
});
function callAsyncJson(method, value) {
const callerId = parseInt(Math.random() * 1000000);
const callPromise = new Promise((resolve, reject) => {
callers[callerId] = { resolve: resolve, reject: reject };
asyncJson.send({ callerId: callerId, method: method, value: value });
});
return callPromise;
}
function JsonStringify(value) {
return callAsyncJson('stringify', value);
}
function JsonParse(value) {
return callAsyncJson('parse', value);
}
JsonStringify({ a: 1 }).then(console.log.bind(console));
JsonParse('{ "a": "1" }').then(console.log.bind(console));
Note: this is just one example, but knowing this you can figure out other improvements or other ways to do it. Hope this is helpful.
Check this out, another npm package-
async-json is a library that provides an asynchronous version of the standard JSON.stringify.
Install-
npm install async-json
Example-
var asyncJSON = require('async-json');
asyncJSON.stringify({ some: "data" }, function (err, jsonValue) {
if (err) {
throw err;
}
jsonValue === '{"some":"data"}';
});
Note-Didn't test it, you need to manually check it's dependency and
required packages.
By asynchronous I assume you actually mean non-blocking asynchronous - i.e., if you have a large (megabytes large) JSON string, and you stringify, you don't want your web server to hard freeze and block newly incoming web requests for 500+ milliseconds while it processes the object.
Option 1
The generic answer is to iterate through your object piece by piece, and to then call setImmedate whenever a threshold is reached. This then allows other functions in the event queue to run for a bit.
For JSON (de)serialization, the yieldable-json library does this very well. It does however drastically sacrifice JSON processing time (which is somewhat intentional).
Usage example from the yieldable-json readme:
const yj = require('yieldable-json')
yj.stringifyAsync({key:"value"}, (err, data) => {
if (!err)
console.log(data)
})
Option 2
If processing speed is extremely important (such as with real-time data), you may want to consider spawning multiple Node threads instead. I've used used the PM2 Process Manager with great success, although initial setup was quite daunting. Once it works however, the final result is magic, and does not require modifying your source code, just your package.json file. It acts as a proxy, load balancer, and monitoring tool for Node applications. It's somewhat analogous to Docker swarm, but bare metal, and does not require a special client on the server.

Get real response of ngResource save()

I have the following situation:
I use ngResource to save some data to the mysql database and after the successfull save() I want to log the json response the server sends to me:
Document.save({}, postData, function(response){
console.log(response);
});
This does not result in a simple response, but in something like an object with its own methods. I want some smple output like the response.data after an $http.$get:
{
"docClass":"testets",
"colCount":1,
"columns":null,
"groupid":7,
"id":19,
"lang":"de",
"title":"test",
"version":1409849088,
"workflow":"12234"
}
Greets
Check out this answer
Promise on AngularJS resource save action
So I think in your case you need to do
var document = new Document(postData);
document.$save()
.then(function(res){});
But also from the link I provided
This may very well means that your call to $save would return empty reference. Also then is not available on Resource api before Angular 1.2 as resources are not promise based.

AngularJS - access elements in scope

I have done a service that gets a json file from the server with the translated values of the labels of my webapp. Seems to work fine:
mobilityApp.service('serveiTraduccions', function($resource) {
this.getTranslation = function($scope) {
var languageFilePath = 'traduccions/traduccio_en.json';
$resource(languageFilePath).get(function (data) {
$scope.translation = data;
});
};
});
What I am trying to do is acces that "$scope.translation" from my controler, I tried all and nothing worked. The object is saved in my $scope as you can see:
how can I get the values of the "registroBtnRegistro", "registroErrorRegistro" etc ?
Thanks in advance !
I tried:
console.log($scope.translation); -> undefined
console.log($scope['translation']); -> undefined
console.log($scope.translation.registroBtnRegistro); -> TypeError:
Cannot read property 'registroBtnRegistro' of undefined
console.log($scope.translation['registroBtnRegistro']); -> TypeError:
Cannot read property 'registroBtnRegistro' of undefined
Maybe you're trying to access these values from another $scope that not inherits the scope where you've created your translation model.
Try to assign this model directly to $rootScope, so you can access it from every scope:
mobilityApp.service('serveiTraduccions', function($resource, $rootScope) {
this.getTranslation = function() {
var languageFilePath = 'traduccions/traduccio_en.json';
$resource(languageFilePath).get(function (data) {
$rootScope.translation = data;
});
};
});
this answer is a blind attempt because your original post lacks basic information like the call from the controller.
we can refine it until we make it work.
First, you should be returning something from your method:
mobilityApp.service('serveiTraduccions', function($resource) {
this.getTranslation = function() {
var languageFilePath = 'traduccions/traduccio_en.json';
return $resource(languageFilePath);
};
});
You are using $resource but you might as well use basic $http.get(). at least it doesn't look like a restful api to me.
In any case, because it's an asynchronous request, it will not return the list of translated strings, but a resource "class" that allows methods like get, delete or the more general query():
from the docs: default methods are
{ 'get': {method:'GET'},
'save': {method:'POST'},
'query': {method:'GET', isArray:true},
'remove': {method:'DELETE'},
'delete': {method:'DELETE'} };
sidenote: injecting $scope in a service doesn't make much sense to me: services are used to encapsulate common logic accross components. However, you can pass a scope instance as a parameter.
Then, the controller that uses this should have the service injected and use a callback to get the results when they have arrived (asynchronous operation!):
TraduccioCtrl ... {
$scope.translation = {}; // avoid undefined when the view just loads
ServeiTraduccions.getTranslation.query(function (response) {
$scope.translation = response; // and angular's two-way data binding will probably do the rest
});
}
The Angular docs about ng-resource have a working example. Other questions in SO have addressed this already too, like Using AngularJS $resource to get data

Run multiple functions based on a SINGLE form submission (method="post") using Node-express

I am looking to perform multiple actions upon receiving HTML(or EJS) form content using the POST method. I am using Node express, mongoose & mongoDB. Each of the below POST responses work individually but i am unsure how to proceed in updating multiple databases based on ONE SINGLE form submission.
// insert into passport db
app.post('/signup', passport.authenticate('local-signup',
{
successRedirect : '/index', // redirect to the secure profile section
failureRedirect : '/signup', // redirect back to the signup page if there is an error
failureFlash : true // allow flash messages
}));
//insert into my database here
[the content of in the second function is unimportant as that is working fine and has been stripped down for simplification.]
app.post('/signup', function( req, res )
{
new UserDB(
{
user_id : req.body.content,
first_name : req.body.fname,
}).save( function( err, mySite, count )
{
res.redirect( '/index' );
});
});
I have tried redirecting but the form content is not accessible after the redirect so only the first function stores the data (ie. only 1 database is filled).
How would i run both functions within
app.post('/signup',.....
{
...
});
?
Thanks in advance!
You can do this by making one function the callback of the other. This is easy because each function maintains the same Connect middleware signature, function(req, res, next), where req and res are the request and response objects created and manipulated by the application, and next is the next function to call at the end of the current function's execution.
According to the official documentation, passport.authenticate() is a normal piece of middleware. All you need to do is specify the middleware you want to be called next. Express queues middleware functions in the order in which you pass them into app.post. You can do something like this:
app.post('/signup', passport.authenticate('local-signup', {
failureRedirect : '/signup',
failureFlash : true
}),
function(req, res) {
new UserDB({
user_id : req.body.content,
first_name : req.body.fname,
}).save(function(err, mySite, count) {
res.redirect('/index');
});
});
Middleware is an extremely powerful feature of the Express framework and possibly the single most important one to master. This guide would be a great next step if you want to learn more.