Swift - PHP : Textfield value sent over to PHP is received as null - php

Question

I hope you all are doing well and staying safe! :)
I am new to iOS programming. I am trying to post values from a textfield to a MYSQL Database. As a first step, I tried to just print the values received on the PHP end.
The values are printed on the Swift end but on the PHP end, an empty string(null) is received. Could you please help and let me know why the string received on PHP end is null? Please help! I am stuck and unsure of what to do next.
I have tried retrieving values from the database and that code works perfectly fine.
Thanks in advance!
EDITED:
This has been now fixed. The correct code is below -
Swift Code:
struct DatatoPost : Codable{
var name : String
init() {
name = "Empty String"
}
}
var myDatatoPost = DatatoPost()
//Protocol created for this structure so that it can be applied to multiple class (View Controllers) that create a delegate for it(ManageDataDelegate)
protocol ManageDataDelegate {
func updateViewController(_ myManager : ManageData, saveOutputData: OutputData)
func didFailError(error : Error)
}
/* what action is expected to be taken on data reached through PHP file*/
struct ManageData {
var delegate : ManageDataDelegate?
var data : Data
init() {
data = Data()
}
//create POST URL based on function - this is the URL to post data to the backend.
mutating func postPHPData(){
let urlPostString = myConstant.baseURL + myConstant.postPHPValue
print(urlPostString)
performPostOperation(urlPostString)
}
//Steps to create URL and other related objects - prepare data for parsing.
mutating func performPostOperation(_ urlPostString : String) {
//1. Create URL
if let url = URL(string: urlPostString){
//Create request variable
var request : URLRequest = URLRequest(url: url)
request.httpMethod = "POST"
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")
do{
let params : [String : Encodable] = ["name": myDatatoPost.name]
data = try JSONSerialization.data(withJSONObject: params, options: .init())
let body = Data(data).base64EncodedData()
print("Data is: ")
let dataString = String(data: data, encoding: .utf8)
print(dataString)
request.httpBody = body
let requestString = String(data: request.httpBody!, encoding: .utf8)
print("Request String is:")
print(requestString)
//2. Create URLSession
let session = URLSession(configuration: .default)
//3. Give the session a task
let task = session.dataTask(with: request as URLRequest, completionHandler: handlePOST(data:response:error:))
//4. Start the session
task.resume()
}catch{
print(error)
}
}
}
//Function that lists the activities that need to be completed in the URL session - GET Data.
func handlePOST(data : Data?, response : URLResponse?, error: Error?){
if error != nil {
delegate?.didFailError(error: error!)
print("error is")
print(error!)
return
}
if let safeData = data{
let dataString = String(data: safeData, encoding: .utf8)
print(dataString)
}
print(response)
}
}
PHP Code:
<?php
echo "we are here";
// Create connection
$con = mysqli_connect("localhost","username","password","dbname");
echo "we are here again";
// Check connection
if (mysqli_connect_errno())
{
echo "Failed to connect to MySQL: ";
}
$postdata = json_decode(file_get_contents("php://input"),TRUE);
$decoded = base64_decode($postdata);
echo "decoded!";
print_r($decoded,true);
//this value is not printed
echo "postdata";
echo $postdata->name;
//this value is not printed
$name= $postdata["name"];
echo "Name";
echo $postdata["name"];
//this value is not printed
echo "Base 64";
echo base64_decode($postdata["name"]);
echo base64_decode($postdata->name);
//This value is not printed
if (empty($postdata["name"])){
echo "String is empty";
//this is printed
}
if (empty($postdata->name)){
echo "String is empty";
//This is printed
}
echo "Its done";
// Close connections
mysqli_close($con);
?>

Answer 1

You have specified your request’s Content-Type to be application/json. So it should be JSON, free of base64 encoding. The only time you should use base64-encoding is if you are trying to send binary data in JSON. (And even then, in that case, we would reach for application/x-www-form-urlencoded request, not application/json request.)
Anyway, to send JSON request and parse JSON response:
protocol ManageDataDelegate: class {
func didFailError(error: Error)
func didReceiveResponse(object: Any)
}
/* what action is expected to be taken on data reached through PHP file*/
struct ManageData {
weak var delegate: ManageDataDelegate? // delegates should always be weak to avoid strong reference cycle; obviously `ManageDataDelegate` must be class protocol
//create POST URL based on function - this is the URL to post data to the backend.
func postPHPData(name: String) {
let urlPostString = URL(string: MyConstant.baseURL)!.appendingPathComponent(MyConstant.postPHPValue)
print(urlPostString)
performPostOperation(urlPostString, name: name)
}
//Steps to create URL and other related objects - prepare data for parsing.
func performPostOperation(_ url: URL, name: String) {
//Create request variable
var request = URLRequest(url: url)
request.httpMethod = "POST"
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")
do {
let params = ["name": name]
let body = try JSONSerialization.data(withJSONObject: params)
// 1. for diagnostic purposes, let's look at the JSON
if let json = String(data: body, encoding: .utf8) {
print("JSON is:", json)
}
request.httpBody = body
//2. Create URLSession
let session = URLSession(configuration: .default)
//3. Give the session a task
let task = session.dataTask(with: request, completionHandler: handlePOST(data:response:error:))
//4. Start the session
task.resume()
//5. If creating a URLSession locally, make sure to invalidate it when the request is done or else you will leak memory; better, create one `URLSession` and reuse it for all of your requests (and then you don't need/want to invalidate it)
session.finishTasksAndInvalidate()
} catch {
print(error)
}
}
enum ManageDataError: Error {
case unknownError(Data?, URLResponse?, Error?)
case notJsonResponse(String)
}
//Function that lists the activities that need to be completed in the URL session - GET Data.
func handlePOST(data: Data?, response: URLResponse?, error: Error?) {
guard let responseData = data, error == nil else {
let error = error ?? ManageDataError.unknownError(data, response, error)
delegate?.didFailError(error: error)
print("error is")
print(error)
return
}
if let object = try? JSONSerialization.jsonObject(with: responseData) {
delegate?.didReceiveResponse(object: object)
} else if let string = String(data: responseData, encoding: .utf8) {
delegate?.didFailError(error: ManageDataError.notJsonResponse(string))
} else {
delegate?.didFailError(error: ManageDataError.unknownError(data, response, error))
}
print(response ?? "No response")
}
}
There are a variety of refinements buried in the above (if creating a session, you must invalidate it when finished; passing responses to the delegate; making sure delegate reference is weak to avoid strong reference cycles; etc.), but hopefully this illustrates the idea: No base64-encoding is needed or desired with JSON requests.
Note, you have specified the request’s Accept to also be application/json so I would make sure it did precisely that:
<?php
header("Content-Type: application/json");
// Create connection
$con = mysqli_connect("localhost","username","password","dbname");
// Check connection
if (mysqli_connect_errno())
{
$result = [
"success" => false,
"message" => "Failed to connect to MySQL: " . mysqli_connect_error()
];
echo json_encode($result, JSON_PRETTY_PRINT);
exit();
}
$postdata = json_decode(file_get_contents("php://input"), true);
if (isset($postdata["name"]))
{
$result = [
"success" => true,
"name" => $postdata["name"]
];
}
else
{
$result = [
"success" => false,
"message" => "'name' not found",
"postdata" => $postdata
];
}
echo json_encode($result, JSON_PRETTY_PRINT);
// Close connections
mysqli_close($con);
?>
So, this parses the JSON and checks for name, but returning a JSON response, which is what the client was looking for.
There are other refinements I would suggest (e.g. I would use JSONEncoder and JSONDecoder rather than JSONSerialization; not create new URLSession for every request; usually a “network controller” like this would be a reference type so that you can use the same one wherever needed; I would use a framework such as Laravel in the server code, etc.), but I did not want to stray too far from the question at hand.