Develop Reference

How do I search for a data in the database with Node JS, Postgres, and dust js

I'm making a webpage with Node JS with dustjs and PostgreSQL. How do I make a search query in the html, so I can pass the value to the app.get
Do I need to use JQuery?
app.get('/teachers', function(req, res){
pool.connect(function(err, client, done){
if(err) {
return console.error("error", err);
}
client.query('SELECT * FROM teachers', function(err, result){
if(err){
return console.error('error running query', err)
}
res.render('teacherindex', {teachers: result.rows});
done();
});
});
});
app.get('/teachers/:str', (req,res)=>{
pool.connect((err, client, done) => {
if (err) throw err
client.query('SELECT * FROM teachers WHERE name = $1', [req.query.namesearch], (err, result) => {
done()
if (err) {
console.log(err.stack)
} else {
res.render('teacherindex', {teachers: result.rows});
}
})
})
})
This is my JQuery
$("#myBtn").click(function(){
var str = $("#myInput").val();
var url = '/teachers/'+str;
if(confirm('Search Record?')){
$.ajax({
url: url,
type: 'put',
success: function(result){
console.log('Searching');
window.location.href='/teachers';
},
error: function(err){
console.log(err);
}
});
}
});
My HTML
<input type="text" id="myInput" data-id="namesearch">
<button type="button" id="myBtn">Show Value</button>
Thank you!

FINAL ANSWER:
Ok so it turns out the issue you were having was something completely different. You are trying to use server side rendering for this, and I was showing you how to render the retrieved data on the client side.
I have forked, and updated your repo - which can be found at the link below..
Please review my changes and let me know if you have any questions.
Working repo: https://github.com/oze4/hanstanawi.github.io
Demo Video: https://raw.githubusercontent.com/oze4/hanstanawi.github.io/master/fake_uni_demo.mp4
EDIT:
I went ahead and built a repository to try and help you grasp these concepts. You can find the repo here - I tried to keep things as simple and understandable as possible, but let me know if you have any questions.
I had to make some minor changes to the paths, which I have commented explanations on the code in the repo.
I am using a "mock" database (just a JSON object in a different file) but the logic remains the same.
The index.js is the main entry point and contains all route data.
The index.html file is what gets sent to the user, and is the main HTML file, which contains the jQuery code.
If you download/fork/test out the code in that repo, open up your browsers developer tools, go to the network tab, and check out the differences.
Using req.params
Using req.query
ORIGINAL ANSWER:
So there are a couple of things wrong with your code and why you are unable to see the value of the textbox server side.
You are sending a PUT request but your server is expecting a GET request
You are looking for the value in req.query when you should be looking for it in req.params
You are looking for the incorrect variable name in your route (on top of using query when you should be using params) req.query.namesearch needs to be req.params.str
See here for more on req.query vs req.params
More detailed examples below.
In your route you are specifying app.get - in other words, you are expecting a GET request to be sent to your server.. but your are sending a PUT request..
If you were sending your AJAX to your server by using something like /teachers?str=someName then you would use req.query.str - or if you wanted to use namesearch you would do: /teachers?namesearch=someName and then to get the value: req.query.namesearch
If you send your AJAX to your server by using the something like /teachers/someName then you should be using req.params.str
// ||
// \/ Server is expecting a GET request
app.get('/teachers/:str', (req, res) => {
// GET THE CORRECT VALUE
let namesearch = req.params.str;
pool.connect((err, client, done) => {
// ... other code here
client.query(
'SELECT * FROM teachers WHERE name = $1',
// SPECIFY THE CORRECT VALUE
namesearch,
(err, result) => {
// ... other code here
})
})
});
But in your AJAX request, you are specifying PUT.. (should be GET)
By default, AJAX will send GET requests, so you really don't have to specify any type here, but I personally like to specify GET in type, just for the sake of brevity - just more succinct in my opinion.
Again, specifying GET in type is not needed since AJAX sends GET by default, specifying GET in type is a matter of preference.
$("#myBtn").click(function () {
// ... other code here
let textboxValue = $("#myTextbox").val();
let theURL = "/teachers/" + textboxValue;
// OR if you wanted to use `req.query.str` server side
// let theURL = "/teachers?str=" + textboxValue;
if (confirm('Search Record?')) {
$.ajax({
url: theURL,
// ||
// \/ You are sending a PUT request, not a GET request
type: 'put', // EITHER CHANGE THIS TO GET OR JUST REMOVE type
// ... other code here
});
}
});
It appears you are grabbing the value correctly from the textbox, you just need to make sure your server is accepting the same type that you are sending.

Node.js flat-cache, when to clear caches

I have a Node.js server which queries MySQL database. It serves as an api end point where it returns JSON and also backend server for my Express application where it returns the retrieved list as an object to the view.
I am looking into implementing flat-cache for increasing the response time. Below is the code snippet.
const flatCache = require('flat-cache');
var cache = flatCache.load('productsCache');
//get all products for the given customer id
router.get('/all/:customer_id', flatCacheMiddleware, function(req, res){
var customerId = req.params.customer_id;
//implemented custom handler for querying
queryHandler.queryRecordsWithParam('select * from products where idCustomers = ? order by CreatedDateTime DESC', customerId, function(err, rows){
if(err) {
res.status(500).send(err.message);
return;
}
res.status(200).send(rows);
});
});
//caching middleware
function flatCacheMiddleware(req, res, next) {
var key = '__express__' + req.originalUrl || req.url;
var cacheContent = cache.getKey(key);
if(cacheContent){
res.send(cacheContent);
} else{
res.sendResponse = res.send;
res.send = (body) => {
cache.setKey(key,body);
cache.save();
res.sendResponse(body)
}
next();
}
}
I ran the node.js server locally and the caching has indeed greatly reduced the response time.
However there are two issues I am facing that I need your help with.
Before putting that flatCacheMiddleware middleware, I received the response in JSON, now when I test, it sends me an HTML. I am not too well versed with JS strict mode (planning to learn it soon), but I am sure the answer lies in the flatCacheMiddleware function.
So what do I modify in the flatCacheMiddleware function so it would send me JSON?
I manually added a new row to the products table for that customer and when I called the end point, it still showed me the old rows. So at what point do I clear the cache?
In a web app it would ideally be when the user logs out, but if I am using this as an api endpoint (or even on webapp there is no guarantee that the user will log out the traditional way), how do I determine if new records have been added and the cache needs to be cleared.
Appreciate the help. If there are any other node.js caching related suggestions you all can give, it would be truly helpful.

I found a solution to the issue by parsing the content to JSON format.
Change line:
res.send(cacheContent);
To:
res.send(JSON.parse(cacheContent));
I created cache 'brute force' invalidation method. Calling clear method will clear both cache file and data stored in memory. You have to call it after db change. You can also try delete specified key using cache.removeKey('key');.
function clear(req, res, next) {
try {
cache.destroy()
} catch (err) {
logger.error(`cache invalidation error ${JSON.stringify(err)}`);
res.status(500).json({
'message' : 'cache invalidation error',
'error' : JSON.stringify(err)
});
} finally {
res.status(200).json({'message' : 'cache invalidated'})
}
}
Notice, that calling the cache.save() function will remove other cached API function. Change it into cache.save(true) will 'prevent the removal of non visited keys' (like mentioned in comment in the flat-cache documentation.

Neither Node.js PUT or POST routes are presenting the data that is being received

I tried this with a number of different modules and methods.
Even by proving the other modules do work as expected in Node by building a separate test project and testing each module individually.
Posting FROM Node's hosted router to a remote API (not TO Node's hosted API)
This problem is not one of SENDING data to an API. It must IMO a problem in the receiving API's not giving up the data it IS receiving for some reason.
I've proven the PUT or POST calls are sending the data by sending the call to http://httpbin/org. That site shows me I'm sending what I expect to be sending.
Here is how I'm sending. I can even see in the receiving API that that API is certainly getting called successfully.
-- sending -- ((Again. This shows my node.http attempt. But I get the same problem using requestjs, requestifyjs, needlejs))
router.get('/', function (req, res, next) {
var hst = req.headers.host.split(':');
var lookbackURL = 'https://' + req.headers.host + req.baseUrl;
lookbackURL = 'http"httpbin.org/put';
var dat = {
what: 'ever'
, try: 'again'
};
var bdy = JSON.stringify(dat);
var options = {
host: hst[0], port: hst[1], path: req.baseUrl, method: 'PUT'
, headers: { 'Content-Type': 'application/json' }
};
var r = nodeHttp.request(options); r.write(bdy); r.end();
res.sendStatus(200);
});
-- receiving --
router.put('/', function (req, res, next) {
console.log('r', req);
});
No matter what module or method I use, in all cases, the receiving req object doesn't contain the what or try data.
BUT in my test project the data is there as I expect it to be, in all cases.
Doing the same console.log(req); in the test project, reqestjs, requestjs, needlejs, node.http all show a proper body object.
But in this problem there isn't a body object in req.
And sending this put/post to http://httpbin.org I can see the body object is being sent.
Any ideas?

Issue found. And it was something no one on here could have gotten for the code I posted.
For reasons I will not go into I have to take body-parser out this application. This also means app.use() won't have a parser given to it.
And that means I have to deal with getting the data on my own. So I've added a req.on('data') listener to read the chunk from the call to the API.
router.put('/', function (req, res, next) {
var data = '';
req.on('data', function (chunk) {
data += chunk;
.....
});
.....
I also decided to do this as a PUT using Requestify.
This just goes to show how easy it is to become complacent and forget how things really work; the assumption of body-parser (or other things) always being there for instance. Or what it is really doing for you.
NEXT I have to figure out how to get a value out of the `req.on('data) back to the method PUTting to the API. Any tips? Appreciated.

request.body.email is undefined node js server side using http.get

I have a problem where request.body.email returns me undefined.
I wrote this code on my controller on my client side:
wish.controller('wishCtrl',['$scope','$http','$cookies',function($scope,$http,$cookies) {
var user={};
user.email = $cookies.get('cookieEmail');
console.log(user.email);
$http.get("http://localhost:3000/wishlist",user).success(function(data){
$scope.wishController = data;
console.log(data);
});
}]);
here I see - user.email ok so there is no problem here.
on my controller on my server side I wrote:
exports.getData = function(request, response) {
userEmail = request.body.email;
console.log(userEmail);
}
which writes me back undefined.
to call this function I have on my server.js (on the server side)
app.get('/wishlist',wish.getData);
any idea how to fix it?

You are making a GET request. There is no request body in a GET request.
If you want to read query string data then parse request.url.
The Angular documentation for get says that the last argument must be a configuration object. So it looks like you aren't even managing to put your data in the URL either. Pass a configuration too.
$http.get("http://localhost:3000/wishlist",user, {})

because i't get function have to pass the email on the client side this way:
$http.get("http://localhost:3000/wishlist/"+user.email)
and the path of the sever should recognize it that way:
app.get('/wishlist/:email',wish.getData);
and int the controller that way:
userEmail = request.params.email;
console.log(userEmail);

Using the PUT method with Express.js

I'm trying to implement update functionality to an Express.js app, and I'd like to use a PUT request to send the new data, but I keep getting errors using PUT. From everything I've read, it's just a matter of using app.put, but that isn't working. I've got the following in my routes file:
send = function(req, res) {
req.send(res.locals.content);
};
app.put('/api/:company', function(res,req) {
res.send('this is an update');
}, send);
When I use postman to make a PUT request, I get a "cannot PUT /api/petshop" as an error. I don't understand why I can't PUT, or what's going wrong.

You may be lacking the actual update function. You have the put path returning the result back to the client but missing the part when you tell the database to update the data.
If you're using MongoDB and ExpressJS, you could write something like this :
app.put('/api/:company', function (req, res) {
var company = req.company;
company = _.extend(company, req.body);
company.save(function(err) {
if (err) {
return res.send('/company', {
errors: err.errors,
company: company
});
} else {
res.jsonp(company);
}
})
});
This mean stack project may help you as it covers this CRUD functionality which I just used here swapping their articles for your companies. same same.

Your callback function has the arguments in the wrong order.
Change the order of callback to function(req, res).
Don't use function(res, req).

Also if you want to redirect in put or delete (to get adress), you can't use normal res.redirect('/path'), you should use res.redirect(303, '/path') instead. (source)
If not, you'll get Cannot PUT error.

Have you been checking out your headers information?
Because header should be header['content-type'] = 'application/json'; then only you will get the update object in server side (node-express), otherwise if you have content type plain 'text/htm' like that you will get empty req.body in your node app.