Asynchronous calls with AngularJS and Node.js

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);
    });
});
}

What is the code in `usp2Json.getJsonFromStoredProc`? – nikjohn Sep 30 '16 at 13:56 — nikjohn, Sep 30 '16 at 13:56

score 0 · Answer 1 · answered Sep 30 '16 at 13:58

0

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

answered Sep 30 '16 at 13:58

nikjohn

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Thank you for your prompt reply. Question updated with usp2Json code. – Weihui Guo Sep 30 '16 at 14:07
Not sure how I can use 2 way data binding since the result is display using ng-repeat for , not input/textarea. The factory only returns the issueId and rate. – Weihui Guo Oct 06 '16 at 01:13

score 0 · Accepted Answer · edited May 23 '17 at 12:30

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?

Asynchronous calls with AngularJS and Node.js

2 Answers2