HTML tutorial
CSS3 tutorial
Bootstrap tutorial
JavaScript tutorial
JQuery tutorial
AngularJS tutorial
React tutorial
NodeJS tutorial
PHP tutorial
Python tutorial
Python3 tutorial
Django tutorial
Linux tutorial
Docker tutorial
Ruby tutorial
Java tutorial
C tutorial
C ++ tutorial
Perl tutorial
JSP tutorial
Lua tutorial
Scala tutorial
Go tutorial
ASP.NET tutorial
C # tutorial
The data used in the previous chapter static data fetched from a server
The data used in the previous chapter static data fetched from a server.
The server code for fetching dynamic data from a database can be written in many different languages.
Here are some examples:
<?php
header("Access-Control-Allow-Origin: *");
header("Content-Type:
application/json; charset=UTF-8");
$conn =
new mysqli("myServer", "user", "pass", "myDB");
$result = $conn->query("SELECT
CompanyName, City, Country FROM Customers");
$outp = "";
while($rs = $result->fetch_array(MYSQLI_ASSOC)) {
if ($outp != "") {$outp .= ",";}
$outp .= '{"Name":"' . $rs["CompanyName"] . '",';
$outp .= '"City":"' . $rs["City"] . '",';
$outp .= '"Country":"'. $rs["Country"] . '"}';
}
$outp ='{"customers":['.$outp.']}';
$conn->close();
echo($outp);
?>
Requests for data from a different server (other than the requesting page), are called cross-site HTTP requests.
Cross-site requests are common on the web. Many pages load css, images, or scripts from different servers.
However, in modern browsers, HTTP requests from scripts are restricted to the same site for security reasons.
The following line (in the PHP example above) allows access to the page from a cross-site:
header("Access-Control-Allow-Origin: *");
var express = require('express');
var app = express();
app.get('/',
function (req, res) {
var sql = require("mssql");
var config = {user:'user', password:'pass',
server:'myServer', database:'myDB'};
sql.connect(config, function (err) {
if (err)
console.log(err);
var request = new
sql.Request();
request.query('SELECT CompanyName, City, Country FROM Customers', function (err, recordset) {
if
(err) console.log(err)
res.send(recordset);
});
});
});
var server = app.listen(5000, function () {
console.log('Server is running..');
});
@{
Response.AppendHeader("Access-Control-Allow-Origin", "*")
Response.AppendHeader("Content-type",
"application/json")
var db =
Database.Open("myDB");
var query = db.Query("SELECT CompanyName,
City, Country FROM Customers");
var outp =""
var
c = chr(34)
}
@foreach(var row in
query)
{
if outp <> "" then outp = outp + ","
outp = outp + "{" + c + "Name" + c + ":" + c
+ @row.CompanyName + c + ","
outp = outp + c
+ "City" + c + ":" + c
+ @row.City + c + ","
outp = outp
+ c + "Country" + c
+ ":" + c + @row.Country + c + "}"
}
outp ="{" + c
+ "customers" + c + ":[" + outp + "]}"
@outp
<?php
header("Access-Control-Allow-Origin: *");
header("Content-Type:
application/json; charset=ISO-8859-1");
$conn = new COM("ADODB.Connection");
$conn->open("PROVIDER=Microsoft.Jet.OLEDB.4.0;Data Source=myDB.mdb");
$rs = $conn->execute("SELECT CompanyName, City, Country FROM
Customers");
$outp = "";
while (!$rs->EOF) {
if ($outp != "") {$outp .= ",";}
$outp .= '{"Name":"' . $rs["CompanyName"] . '",';
$outp .= '"City":"' . $rs["City"] . '",';
$outp .= '"Country":"'. $rs["Country"] . '"}';
$rs->MoveNext();
}
$outp ='{"customers":['.$outp.']}';
$conn->close();
echo ($outp);
?>
<%@ Import Namespace="System.IO"%>
<%@ Import Namespace="System.Data"%>
<%@ Import Namespace="System.Data.OleDb"%>
<%
Response.AppendHeader("Access-Control-Allow-Origin", "*")
Response.AppendHeader("Content-type",
"application/json")
Dim conn As
OleDbConnection
Dim objAdapter As OleDbDataAdapter
Dim objTable As
DataTable
Dim objRow As DataRow
Dim objDataSet As New DataSet()
Dim outp
Dim c
conn = New OledbConnection("Provider=Microsoft.Jet.OLEDB.4.0;data
source=myDB.mdb")
objAdapter = New OledbDataAdapter("SELECT
CompanyName, City, Country FROM Customers", conn)
objAdapter.Fill(objDataSet,
"myTable")
objTable=objDataSet.Tables("myTable")
outp = ""
c = chr(34)
for each x in objTable.Rows
if outp <> "" then outp = outp & ","
outp = outp & "{" & c & "Name" & c & ":" & c & x("CompanyName")
& c & ","
outp = outp & c & "City" & c & ":" & c
& x("City") & c & ","
outp = outp & c & "Country" & c
& ":" & c & x("Country") & c & "}"
next
outp
="{" & c & "customers" & c & ":[" & outp & "]}"
conn.close
response.write(outp)
%>