Asynchronous calls with AngularJS and Node.js - angularjs

Question

New to AngularJS and Node.js. Please advise.
Because the data I want to display on the page takes quite some time to load. I decide to load the fast data from database_1 first, and then get the slow response from database_2 later. Here is my AngularJS:
var app = angular.module('myApp', [
]);
app.factory('rateFactory', function ($http) {
return $http.get("localhost/rate"); // api or node.js to return only issueId and rate
})
app.controller('SignupController', function ($scope, $http, $filter, rateFactory) {
// Display most of the content first
$scope.showData = function () {
$http.get("localhost/signup") // api or node.js
.success(function (response) {
$scope.Signups = response;
$scope.curPage = 0;
$scope.pageSize = 25;
$scope.numberOfPages = function () {
return Math.ceil($scope.Signups.length / $scope.pageSize);
};
})
.error(function (data, status, headers, config) {
alert(status);
});
}
// Display slow response, Rate, later based on the issueId
$scope.showRate = function (issueId) {
rateFactory
.success(function (data) {
document.getElementById(issueId).innerHTML = data.find(x => x.IssueID === issueId).Rate;
})
.error(function (data, status, headers, config) {
//alert(status);
});
}
});
I wonder whether there is any better way to do it. This my first question.
Next question is about Node.js. If I get the data from ashx or api, it returns the data without any problem. But when using Node.js for both calls, it's a hit and miss. Sometimes it works fine, but most of the time, the 2nd call fails. Am I doing something wrong? Both returns the data perfectly if calling individually. Here is the node.js code:
var express = require('express');
var http = require('http');
var app = express();
var usp2Json = require('./lib/usp2Json.js');
app.get('/iisnode/myApp/signup', function(req, res) {
usp2Json.getJsonFromStoredProc('stroedprocToGetSignup', req, res);
});
app.get('/iisnode/myApp/rate', function(req, res) {
usp2Json.getJsonFromStoredProc('stroedprocToGetRate', req, res);
})
var server = http.createServer(app);
var port = process.env.PORT || 593;
server = app.listen(port, function() {
console.log('Server is running...');
});
usp2Json.js is a custom module to get data from SQL Server with a stored procedures:
exports.getJsonFromStoredProc = function(storedproc, req, res) {
var sql = require("mssql");
var express = require('express');
var app = express();
res.header('Access-Control-Allow-Origin', '*');
res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE,OPTIONS');
res.header('Access-Control-Allow-Headers', 'Content-Type, Authorization, Content-Length, X-Requested-With');
// config database
var config = {
user: 'username',
password: 'password',
server: 'servername',
database: 'databasename',
};
// connect to database
sql.connect(config, function(err) {
if(err) console.log(err);
// create Request object
var request = new sql.Request();
// query to the database and get the records
request.query(storedproc, function(err, recordset) {
if(err)
console.log(err);
// send records as a response
res.send(recordset);
});
});
}

Answer 1

One suggestion I have is to get rid of:
document.getElementById(issueId).innerHTML = data.find(x => x.IssueID === issueId).Rate;
And use regular Angular 2 way data binding, and bind your #issueId element to a $scope.issueId scope variable, and update the scope variable on call success. The way it is done right now is sort of an anti-pattern.
In terms of the NodeJS API call, you will need to show us what the route handler i.e. usp2Json.getJsonFromStoredProc does in it's code. Otherwise your code looks perfectly fine

Answer 2

In terms of the NodeJS API call, the issue is actually the SQL Server connection. When I looked at console.log, it doesn't give me enough information, but simply says "Server is running". I had to add a line to get the details of error:
request.query(storedproc, function (err, recordset) {
if (err) {
fs.appendFile("path"+ datetime+".txt", time + " Error on executing " + storedproc + " - " + err + " \r\n")
//throw (err);
}
// send records as a response
res.send(recordset);
});
This gives me "ConnectionError: Connection is closed.". With this information, I was able to find the solution from here:
https://github.com/patriksimek/node-mssql/issues/138
and answer from Stackoverflow: How can I use a single mssql connection pool across several routes in an Express 4 web application?