I am a long time PHP developer who decided to give node.js and express a try today. I am trying to find the best way to merge my results into a single object. I may be approaching this to much like a PHP developer and could use some assistance. Thanks in advance.
app.get('/api/posts', function(req, res) {
url_parts = url.parse(req.url, true)
query = url_parts.query
current_page = query.page || 1
items_per_page = 50
start_index = (current_page - 1) * items_per_page
max_page = 1000
var getPosts = {
db: function() {
var posts = {}
connection.query('SELECT COUNT(*) AS count FROM rss', function(err, rows1, fields) {
if (!err)
{
total_pages = Math.ceil(rows1[0].count / items_per_page)
if (start_index < rows1[0].count || start_index < max_page)
{
sql = 'SELECT id, title, image, width, height, url FROM rss ORDER BY date DESC LIMIT '+start_index+', '+items_per_page
connection.query(sql, function(err, rows2) {
if (!err)
{
for (var i in rows2)
{
comments = 'SELECT comment FROM comments WHERE section_id = '+rows2[i].id+' ORDER BY date DESC'
connection.query(comments, function(err2, rows3) {
//COMBINE RESULTS HERE
//rows2[i].comments = rows3
});
}
//res.json(rows2)
// DISPLAY RESULTS HERE
}
else
{
console.log(err)
}
});
}
}
else
{
console.log(err)
}
});
}
}
getPosts.db();
});
Whatever you do, do NOT create loops with Node. That will simply create a blocking call. You need to use callbacks. You can do those manually or use a library that helps. I like asynch (https://github.com/caolan/async) so here is looping code replaced with async.
async.forEachSeries(rows1, function(row, callback) {
sql = 'SELECT id, title, image, width, height, url FROM rss ORDER BY date DESC LIMIT '+start_index+', '+ items_per_page
connection.query(sql, function(err, rows2) {
if (!err) {
async.forEachSeries(rows2, function(row2, callback2) {
// do whatever processing you will do here.
// now call the callback2 to signal you have finished processing.
callback2();
},function(err) {
// handle any errors that might occur in your 'loop' here.
});
}
callback()
},function(err) {
});
Another suggestion for your code is that you should never build out your SQL manually. Use ? params. For example:
connection.query("SELECT id, title, image, width, height, url FROM rss ORDER BY date DESC LIMIT ?,?", [start_index, items_per_page], function(err, rows, fields) {
...do your processing
}
Hope this helps.
AlexGrad is right about using the async module, it will help you organize your code better (and can also help with blocking the event loop, but that's very unlikely to be the case here). You should also follow his advise on using the ? character for escaping.
For your actual question, combining the results by adding them as ad-hoc properties is fine.