Develop Reference

How do I transfer the PHP variables to another javascript file?

So my goal is to use PHP to get data from a PostGreSQL database. I want to use this data in a separate javascript file so I can display it on the screen a certain way that I have my website configured. All the tutorials that I have seen online just puts a script tag inside the PHP file but I cannot do that because my website display javascript code is in the separate file. I just need the numbers to be in the javascript file that I got from the PHP file that got its data from the PostGreSQL database. How can I do this?
I just need help with the means to get to the ends because I have researched on my own but it is always not exactly what I want.
PHP:
<?php
$myPDO = new PDO('pgsql:host=myHost; dbname=myDBName', 'myUsername', 'myPassword');
?>
$result = $myPDO->query("SELECT * FROM table WHERE id = 'someID'");
Now I want to use this row's values in another javascript file. How can I do this?

You could use Ajax for this.
You could so something like this in your JS file:
$.ajax({
type: "GET",
url: 'FILENAME.php',
success: function(data){
alert(data);
}
});
and then in your FILENAME.PHP just return the values.
Your JS should then pull through whatever has been returned, in this case, your database query.

Your JS file needs to request the data from your PHP controller, via an AJAX request. You can then manipulate the returned data object whichever way you like.

We have mainly two methods to pass php value to javascript variable
Simple variable method at the time of first page load
<script>
var js_variable = <?php echo $data_php_variable; ?> ;
//this is working only at the first time of the page load
//you can also parse the data to any format
</script>
Use AJAX call to trigger a PHP request and manipulate return PHP value in JS
$.ajax({
type: "GET", //get or post method
url: 'FILENAME.php', //php request url
data :{}, //optional ,you can send data with request
success: function(res){
// this 'res' variable is the php return data in the form of js data
console.log(res);
}
});
ajax method is more dynamic ,it can use any time request handling

use the javascript ajax to call a php api
pass your data at php in your view file , use something like:
var phpData = JSON.parse("<?php echo json_encode($data)); ?>");

json_decode expects parameter 1 to be string, says array is given. Why doesn't my string pass properly?

So, I've been struggling with this for the entire weekend and I still can't figure out what's wrong. I'm trying to pass some data through json_decode to be able to save it to a file and I keep getting the error it expects a string but an array is given. I'm using jQuery and PHP.
The data I send through the ajax call is, according to console.log(noBrack):
{"ID":2,"LLID":"LLID2","volNaam":"Test - 0","norm":"Zicht","instalDatum":"17-11-2017","endDate":"18-11-2017","serie":"0","klant":"Testklant","file":"data/Testklant (Heerenveen)/LLID2.json","gelDat":"27-10-2018"}
My Ajax call is:
$.ajax({
url: 'quickGrade.php',
type: 'POST',
data: noBrack,
datatype: 'json',
success:function(data){
alert(data );
}
});
My PHP code is:
$testSave = 'data/gradeTest.json';
$decode = json_decode($_POST, true);
file_put_contents($testSave, $decode);
Can anyone find out what I'm doing wrong? I've tested my string with an online json_decode tester and it said it was valid so I'm kinda hardstuck here.

The way you are sending data will give you $_POST array in php code. So actually you do not need to decode because the data is coming as $_POST array not a JSON string.

You should use json_encode to get JSON string to store in file. Because $_POST is an array, so you can't decode it like a Json string.
Your code will become this:
$testSave = 'data/gradeTest.json';
file_put_contents($testSave, json_encode($_POST));
You can read more about:
http://php.net/manual/en/function.json-encode.php
http://php.net/manual/en/function.json-decode.php

Access array posted with Javascript

I'm using the following code to send a form to a php processor:
$(document).ready(function(){
var $form = $('form');
$form.submit(function(){
$.post($(this).attr('action'), $(this).serialize(), function(response){
// do something here on success
},'json');
return false;
});
});
I presume that this sends the form to my php script with all the form values in json format but I then don't know how to then access this json and turn it back into the array i need to process in my PHP script.
Does anyone know how I access this variable in my processor script so I can process the data?
Also, what is the best way for me to view the data being posted so I can work out what to do with it, when I send the data the processor is obviously not displayed, is there a way to echo out/write the information received by the script to I can view it?

You can easily access to the json as an array called "$_POST" in your php.
for example, if you send the form as a json structured like this:
{
"name":"userID",
"psw":"password123"
}
in your php script there will be the variable $_POST with this structure:
$_POST = Array (
"name" => "userID",
"psw" => "password123"
)
EDIT
In a comment you asked me how to display the data received from the server,
that's quite simple,
in your php script just write this:
echo json_encode($_POST);
so that you output the $_POST array in the json format,
then in your script write this:
$.post($(this).attr('action'), $(this).serialize(),
function(data){ //"data" argument will contain the output from the server (that is the encoded $_POST array printed as json with the php code as showed above)
console.log(data); //log data
}
); //as you can see, I've deleted "json", becouse it's unuseful

Incorrect format of data sent by $.post to PHP

I'm trying to send a JavaScript Object() to a PHP file in the correct format that $.POST wants. The PHP file doesn't set any $_POST[] variables so i must be sending it in an incorrect format.
JS:
$('#downloadBtn').click(function(){
var form_data = new Object();
form_data.filepath = $("#fileName").html();
$.post(
"/UpdateDownloads.php",
{ JSON.stringify(form_data) },
function(data) {
alert(data);
}
);
});
I know that changing the sent data to "{ filepath: form_data.filepath }" will fix the problem, but this is a sloppy fix because it doesn't change as i add more and more data to form_data. Basically im wondering if there is a JS function that can transform my Object() variable into a form which POST will accept and set the $_POST['filepath'] variables that i add to my form_data Object().

You can try sending the data as
{'data':JSON.stringify(form_data)}
Then on server side you will get $_POST['data']
which you can convert into object by using
json_decode($_POST['data']);
I hope this will work

passing JSON data and getting it back

I'm new to passing objects through AJAX, and since I am unsure of both the passing and retrieving, I am having trouble debugging.
Basically, I am making an AJAX request to a PHP controller, and echoing data out to a page. I can't be sure I'm passing my object successfully. I am getting null when printing to my page view.
This is my js:
// creating a js filters object with sub arrays for each kind
var filters = {};
// specify arrays within the object to hold the the list of elements that need filtering
// names match the input name of the checkbox group the element belongs to
filters['countries'] = ["mexico", "usa", "nigeria"];
filters['stations'] = ["station1", "station2"];
filters['subjects'] = ["math", "science"];
// when a checkbox is clicked
$("input[type=checkbox]").click(function() {
// send my object to server
$.ajax({
type: 'POST',
url: '/results/search_filter',
success: function(response) {
// inject the results
$('#search_results').html(response);
},
data: JSON.stringify({filters: filters})
}); // end ajax setup
});
My PHP controller:
public function search_filter() {
// create an instance of the view
$filtered_results = View::instance('v_results_search_filter');
$filtered_results->filters = $_POST['filters'];
echo $filtered_results;
}
My PHP view:
<?php var_dump($filters);?>
Perhaps I need to use a jsondecode PHP function, but I'm not sure that my object is getting passed in the first place.

IIRC the data attribute of the $.ajax jQuery method accepts json data directly, no need to use JSON.stringify here :
data: {filters: filters}
This way, you're receiving your json data as regular key/value pairs suitable for reading in PHP through the $_POST superglobal array, as you would expect.

http://blog.teamtreehouse.com/beginners-guide-to-ajax-development-with-php
When you use ajax the page is not reloaded so the php variable isn't of use.
You may want to look for a tutorial to help. I put one at the beginning as I don't see how to format this on my tablet
you will need to json_encode your response as the tutorial shows
you may want to print to a log on the server when you are in the php function and make it world readable so you can access it via a browser
I like to use the developer tools in Chrome to see what is actually returned from the server