Chaining together promises with a db insert - node.js

Question

I'm struggling trying to chain together three requests that require synchrony in node.js. Here is my attempt at using promises, but i am getting an error saying that db.run isn't a function. The first action should insert into my sqlite db. The most important thing i need is the
this.lastID variable, which lists the id of the last enetered item. Before attempting to use promises, I was having trouble with scoping. This is important because i need to take this value and use use it in my JSON object under the callback key. Lastly, Im using the requests npm package to send the request.
I am using the bluebird promises library, sqlite3 npm package, nodejs, express.
Any help with this would be awesome because I'm lost.
function db() {
return new Promise(function(resolve, reject) {
db.run(`INSERT INTO scan_requests(name, date) VALUES(?,?);`, [name,date], function(err) {
if (err) {
console.log(err)
}
let q = this.lastID
resolve(q)
})
})
}
db()
.then(function(q) {
let options = {
url: 'API',
body: {
name: req.name,
scan_callback: `http://localhost:80/${q}`
},
json: true
}
resolve(options)
}).then(function(options) {
console.log(options)
})

Answer 1

1st rule of "promises" ... always return your "promises". Except when you create a new one.
Try this ...
app.post('/route', function (req,res) {
new Promise(function(resolve, reject) {
db.run(`INSERT INTO scan_requests(req.name,req.date) VALUES(?,?);`, [name,date]).then(function(result) {
let options = {
url: 'http://API',
body: {
name: req.name,
date: req.date
callback: `http://localhost:80/${this.lastID}`,
},
json: true
}
// this resolves this promise ... it is now passed on
resolve(options);
}).then(function(options) {
// options is now the result from the promise
console.log(options)
request
.post(options)
.on('error', function(err) {
console.log(err)
})
.pipe(res)
});
});
});
UPDATE (question modified)
You're using resolve(options) but resolve is not in scope there (it doesn't exist). Remember the first rule of promises ...
db()
.then(function(q) {
let options = {
url: 'API',
body: {
name: req.name,
scan_callback: `http://localhost:80/${q}`
},
json: true
}
// *** change the following line ***
// --- you must return your data ---
return options;
}).then(function(options) {
console.log(options)
// -------------------------
// --- contrived example ---
// -------------------------
return { success: true };
}).then(status => {
console.log(`Success ${status.success}`);
});
The example includes a rather useless but illustrative example of how to continue passing data down the "promise chain".