I know it will be a trivial thing, but for this, I have not found much around, I'm using node/express js to query a database (MySQL), I'm using the following mode for queries:
index.js
exports.view= function(req, res){
var name = req.params.name;
req.getConnection(function(err,connection){
var query = connection.query('SELECT * FROM event WHERE linkname = ?',[name],function(err,rows)
{
if(err){
console.log("Error Selecting : %s ",err );
res.redirect('/');
}else{
console.log("rows: %s",rows);
var body = JSON.parse(JSON.stringify(rows));
console.log("body: %s",body);
res.render('form_payment',{page_title:"Showroom",data:rows});
}
});
});
};
I would like to view the video, or in any case be able to use part of the query data, I read that you can use JSON.stringify(), JSON.parse() or both, but I always print the empty string on the screen, even when I try to print rows:
rows:
body:
The query works perfectly, in fact, I can pass the json of rows to the next activity with res.render (), but in this function (view) I just can not get and then use this data. My idea would be to be able to easily use the contents of rows, for example, something like rows[0].name, rows[0].id or rows.name, rows.code, ...
[SOLVED]
Remember to check if the variables that are passed to the query are correct, once this problem has been solved everything is back to work correctly and access to the rows elements, can occur with rows[0].id, rows[0].name, ...
I hope you can also help you find yourself in this situation.
Related
I want to access resources from a SQLite database table. I have one table for accounts, one for movies and one for reviews. The reviews-table is constructed like this:
CREATE TABLE IF NOT EXISTS reviews (
id INTEGER PRIMARY KEY,
authorId INTEGER,
movieId INTEGER,
review TEXT,
rating INTEGER,
FOREIGN KEY('authorId') REFERENCES 'accounts'('id'),
FOREIGN KEY('movieId') REFERENCES 'movies'('id')
)
What I want to do is that I want to be able to get all reviews, made by one author. But I also want to be able to get all reviews, made for the same movie. Below is my code for getting all reviews made by the same user/author. The code looks the same when getting the reviews based on the movie, with a few changes.
Both of them does what I want them to do. But of course only the one written first in the file are running.
const authorId = request.params.authorId;
const query = "SELECT * FROM reviews WHERE authorId = ?";
const values = [authorId];
db.all(query, values, function (error, review) {
if (error) {
response.status(500).end();
} else if (!review) {
response.status(404).end();
} else {
response.status(200).json(review);
}
});
});
The url will look the same no matter which of them I want running; http://localhost:3000/reviews/3. How can I differentiate the url so that they know which one should run?
I have tried to experiment with query strings, but I'm not sure how that works, and after hours of searching for something that worked on my code, I gave up.
I have also been thinking about using something like
app.use(function (request, response, next) {
if (request.method == "GET" && request.uri == "/reviews/:authorId") {
response.send("Hello World");
} else {
next;
}
});
This didn't work, and it didn't work if I tried to remove ":authorId" from the url either. The page just keeps loading.
So how do I solve this?
The most dynamic would be a single route /reviews and use the query string with the params like ?author=123 or ?movie=123, they can be combined like ?author=123&movie=123. As you want to return JSON the code will be used via API, so the pretty path is usually not as important as when it is a web-url. To make the implementation effective, most people use a function where you can drop the query object in and get the where-clause, or use an ORM.
In express, when you have routers like '/reviews/:authorId' and then '/reviews/:movieId', then the second one will never be called, because the first one will always match. That is something to be careful about when organizing your express routes.
I'm trying to make a MySQL query to filter data from a table. Effectively what I want to do is:
SELECT data FROM table WHERE column IN ?
The filter is coming from checkboxes in a form on a webpage, so I can pass an array or object fairly easily, but it'll be a varying number of parameters for the IN each time, so I can't us multiple ?. I tried making a for loop to make multiple queries concatenate the arrays that the queries returned, but I ran into scope issues with that. I also tried passing an array directly to the query, but that throws a syntax error. I'm sure there's a straightforward answer to this but I'm not sure how to do it.
Edit: source code added:
Here's where I'm at:
const filterShowQuery = `SELECT sl_Show.showId, sl_Band.BandName,
sl_Show.date, sl_Venue.venueName,
sl_Show.length, sl_Show.attendance, sl_Show.encore FROM sl_Show
JOIN sl_Band on sl_Show.BandID = sl_Band.BandId
JOIN sl_Venue on sl_Show.VenueId = sl_Venue.VenueId
WHERE sl_Band.BandName IN (?)
ORDER BY sl_Band.BandName;`;
Trying to get an array into the ? in WHERE sl_Band.BandName IN
const getShows = (req, res,next) =>{
var {bands, venues} = req.body;
var i = 0; //left over from previous attempt
var data = [];
for (b in bands){
mysql.pool.query(filterShowQuery, bands[b], (err, result) => {
if(err){
console.log('filter band error');
next(err);
return;
}
data = data.concat(result);
console.log(data); //data concatenates property and increases through for loop
})
// same action to be performed with venues once solved
// for (v in venues){
// conditions[i] = venues[v];
// i++;
console.log(data); //data is empty when logging from here or using in res
res.json({rows:data});
}
}
SECURITY WARNING!
I must to say: NEVER, NEVER PASS DATA DIRECTLY TO YOUR SQL!
If you don't know why, just google for SQL Injection. There are lots of examples on how it is done, how easily it can be done, and how to protect your application from this sort of attack.
You should always parametrize your queries. But in the very rare case which you really need to insert data concatenating a string into your sql, validate it before.
(E.g.) If it's a number, than use a Regex or some helper method to check if the value you are inserting into your SQL String is really and only a number and nothing else.
But aside that, you did not provide any source code, so it's really hard to give any help before you do that.
I have used tedious to connect to sql server and restify for restful api
here is the server.js
server.get('/getInvoiceData', function (req, res, next) {
repository.GetInvoiceData(function(data){
res.send(data);
next();
});
});
and the invoice.js
exports.GetInvoiceData = function(callback){
var query = "SELECT * FROM [Snapdeal].[dbo].[tbl_Configuration]";
var req = new request(query,function(err,rowcount){
if (err)
{
console.log(err.toString());
}else{
console.log(rowcount+ " rows");
}
});
req.on('row',function(){
callback({customernumber:123});
});
connection.execSql(req);
}
I am getting the error as Cant set the headers after they are sent.
I am not 100% sure as I am not familiar with the SQL lib you are using, however, it looks to me like the problem is your row event would be raised per row, rather than per transaction.
You are ending the response after the first row event therefore if there is more than one row being returned the response will already have been closed (hence the error).
One way of dealing with this is to accumulate the row data as it's being retrieved and then raise the callback after your done
Now that you have stated the lib you are using (Tedius), it would appear my hunch was correct. Looking at the library, here is the simplest approach you can take to returning all the rows in a single callback
exports.GetInvoiceData = function(callback){
var query = "SELECT * FROM [Snapdeal].[dbo].[tbl_Configuration]";
var req = new request(query,function(err, rowcount, rows){
if (err) {
console.log(err.toString());
} else{
callback(rows);
}
});
connection.execSql(req);
}
Note - remember to set config.options.rowCollectionOnRequestCompletion to true otherwise the rows parameter will be empty.
My issue, using mssql, was that I had a default value or binding set (in this case, (getdate())) to one of my columns (modified date column). However, the data I was trying to retrieve had preset NULL values for this particular column.
I put data in those rows and I was good to go.
How simultaneously to render a page and transmit my custom data to browser. As i understood it needs to send two layers: first with template and second with JSON data. I want to handle this data by backbone.
As i understood from tutorials express and bb app interact as follows:
res.render send a page to browser
when document.ready trigger jQuery.get to app.get('/post')
app.get('/post', post.allPosts) send data to page
This is three steps and how to do it by one?
var visitCard = {
name: 'John Smit',
phone: '+78503569987'
};
exports.index = function(req, res, next){
res.render('index');
res.send({data: visitCard});
};
And how i should catch this variable on the page- document.card?
I created my own little middleware function that adds a helper method called renderWithData to the res object.
app.use(function (req, res, next) {
res.renderWithData = function (view, model, data) {
res.render(view, model, function (err, viewString) {
data.view = viewString;
res.json(data);
});
};
next();
});
It takes in the view name, the model for the view, and the custom data you want to send to the browser. It calls res.render but passes in a callback function. This instructs express to pass the compiled view markup to the callback as a string instead of immediately piping it into the response. Once I have the view string I add it onto the data object as data.view. Then I use res.json to send the data object to the browser complete with the compiled view :)
Edit:
One caveat with the above is that the request needs to be made with javascript so it can't be a full page request. You need an initial request to pull down the main page which contains the javascript that will make the ajax request.
This is great for situations where you're trying to change the browser URL and title when the user navigates to a new page via AJAX. You can send the new page's partial view back to the browser along with some data for the page title. Then your client-side script can put the partial view where it belongs on the page, update the page title bar, and update the URL if needed as well.
If you are wanting to send a fully complete HTML document to the browser along with some initial JavaScript data then you need to compile that JavaScript code into the view itself. It's definitely possible to do that but I've never found a way that doesn't involve some string magic.
For example:
// controller.js
var someData = { message: 'hi' };
res.render('someView', { data: JSON.stringify(someData) });
// someView.jade
script.
var someData = !{data};
Note: !{data} is used instead of #{data} because jade escapes HTML by default which would turn all the quotation marks into " placeholders.
It looks REALLY strange at first but it works. Basically you're taking a JS object on the server, turning it into a string, rendering that string into the compiled view and then sending it to the browser. When the document finally reaches the browser it should look like this:
// someSite.com/someView
<script type="text/javascript">
var someData = { "message": "hi" };
</script>
Hopefully that makes sense. If I was to re-create my original helper method to ease the pain of this second scenario then it would look something like this:
app.use(function (req, res, next) {
res.renderWithData = function (view, model, data) {
model.data = JSON.stringify(data);
res.render(view, model);
};
next();
});
All this one does is take your custom data object, stringifies it for you, adds it to the model for the view, then renders the view as normal. Now you can call res.renderWithData('someView', {}, { message: 'hi' });; you just have to make sure somewhere in your view you grab that data string and render it into a variable assignment statement.
html
head
title Some Page
script.
var data = !{data};
Not gonna lie, this whole thing feels kind of gross but if it saves you an extra trip to the server and that's what you're after then that's how you'll need to do it. Maybe someone can think of something a little more clever but I just don't see how else you'll get data to already be present in a full HTML document that is being rendered for the first time.
Edit2:
Here is a working example: https://c9.io/chevex/test
You need to have a (free) Cloud9 account in order to run the project. Sign in, open app.js, and click the green run button at the top.
My approach is to send a cookie with the information, and then use it from the client.
server.js
const visitCard = {
name: 'John Smit',
phone: '+78503569987'
};
router.get('/route', (req, res) => {
res.cookie('data', JSON.stringify(pollsObj));
res.render('index');
});
client.js
const getCookie = (name) => {
const value = "; " + document.cookie;
const parts = value.split("; " + name + "=");
if (parts.length === 2) return parts.pop().split(";").shift();
};
const deleteCookie = (name) => {
document.cookie = name + '=; max-age=0;';
};
const parseObjectFromCookie = (cookie) => {
const decodedCookie = decodeURIComponent(cookie);
return JSON.parse(decodedCookie);
};
window.onload = () => {
let dataCookie = getCookie('data');
deleteCookie('data');
if (dataCookie) {
const data = parseObjectFromCookie(dataCookie);
// work with data. `data` is equal to `visitCard` from the server
} else {
// handle data not found
}
Walkthrough
From the server, you send the cookie before rendering the page, so the cookie is available when the page is loaded.
Then, from the client, you get the cookie with the solution I found here and delete it. The content of the cookie is stored in our constant. If the cookie exists, you parse it as an object and use it. Note that inside the parseObjectFromCookie you first have to decode the content, and then parse the JSON to an object.
Notes:
If you're getting the data asynchronously, be careful to send the cookie before rendering. Otherwise, you will get an error because the res.render() ends the response. If the data fetching takes too long, you may use another solution that doesn't hold the rendering that long. An alternative could be to open a socket from the client and send the information that you were holding in the server. See here for that approach.
Probably data is not the best name for a cookie, as you could overwrite something. Use something more meaningful to your purpose.
I didn't find this solution anywhere else. I don't know if using cookies is not recommended for some reason I'm not aware of. I just thought it could work and checked it did, but I haven't used this in production.
Use res.send instead of res.render. It accepts raw data in any form: a string, an array, a plain old object, etc. If it's an object or array of objects, it will serialize it to JSON for you.
var visitCard = {
name: 'John Smit',
phone: '+78503569987'
};
exports.index = function(req, res, next){
res.send(visitCard};
};
Check out Steamer, a tiny module made for this this exact purpose.
https://github.com/rotundasoftware/steamer
Most elegant and simple way of doing this is by using rendering engine (at least for that page of concern). For example use ejs engine
node install ejs -s
On server.js:
let ejs = require('ejs');
app.set('view engine', 'ejs');
then rename desired index.html page into index.ejs and move it to the /views directory. After that you may make API endpoit for that page (by using mysql module):
app.get('/index/:id', function(req, res) {
db.query("SELECT * FROM products WHERE id = ?", [req.params.id], (error, results) => {
if (error) throw error;
res.render('index', { title: results[0] });
});
});
On the front-end you will need to make a GET request, for example with Axios or directly by clicking a link in template index.ejs page that is sending request:
<a v-bind:href="'/index/' + co.id">Click</a>
where co.id is Vue data parameter value 'co' that you want to send along with request
I have meteor method that does an insert.
Im using Regulate.js for form validation.
I set the game_id field to Meteor.uuid() to create a unique value that I also route to /game_show/:game_id using iron router.
As you can see I'm logging the details of the game, this works fine. (image link to log below)
file: /lib/methods.js
Meteor.methods({
create_game_form : function(data){
Regulate.create_game_form.validate(data, function (error, data) {
if (error) {
console.log('Server side validation failed.');
} else {
console.log('Server side validation passed!');
// Save data to database or whatever...
//console.log(data[0].value);
var new_game = {
game_id: Meteor.uuid(),
name : data[0].value,
game_type: data[1].value,
creator_user_id: Meteor.userId(),
user_name: Meteor.user().profile.name,
created: new Date()
};
console.log("NEW GAME BEFORE INSERT: ", new_game);
GamesData.insert(new_game, function(error, new_id){
console.log("GAMES NEW MONGO ID: ", new_id)
var game_data = GamesData.findOne({_id: new_id});
console.log('NEW GAME AFTER INSERT: ', game_data);
Session.set('CURRENT_GAME', game_data);
});
}
});
}
});
All of the data coming out of the console.log at this point works fine
After this method call the client routes to /game_show/:game_id
Meteor.call('create_game_form', data, function(error){
if(error){
return alert(error.reason);
}
//console.log("post insert data for routing variable " ,data);
var created_game = Session.get('CURRENT_GAME');
console.log("Session Game ", created_game);
Router.go('game_show', {game_id: created_game.game_id});
});
On this view, I try to load the document with the game_id I just inserted
Template.game_start.helpers({
game_info: function(){
console.log(this.game_id);
var game_data = GamesData.find({game_id: this.game_id});
console.log("trying to load via UUID ", game_data);
return game_data;
}
});
sorry cant upload images... :-(
https://www.evernote.com/shard/s21/sh/c07e8047-de93-4d08-9dc7-dae51668bdec/a8baf89a09e55f8902549e79f136fd45
As you can see from the image of the console log below, everything matches
the id logged before insert
the id logged in the insert callback using findOne()
the id passed in the url
However the mongo ID and the UUID I inserted ARE NOT THERE, the only document in there has all the other fields matching except those two!
Not sure what im doing wrong. Thanks!
The issue is your code is running on the client side (or at least it looks like from the screenshot).
In meteor, Meteor.methods that run on the client side are simulation stubs. What this means is you put stuff in there that creates 'fake' data so that you can avoid the user feeling latency. This is because it would take 1-4 seconds for the server to reply with what was actually inserted in the database. This isn't really an issue though.
The reason this causes you trouble is the method is run twice (one on the server and one on the client), so it generates two different Meteor.uuids since they are random. So this is why you have the inconsistency. What you see is the 'fake' one initially, then the server sends down the real one.
This is how Meteor makes it look like data has been inserted instantly, even though its not fully yet inserted.
To fix this get rid of the the .method you have on the client so that you only have one running on the server. You would need to get the game_id from the server though and not from the client.
If you want to keep the latency compensation, pass the Meteor.uuid in data like you do your other form data. This way the game_id will be consistent on both the server and client.