1

I can't pass multiple variable from PHP (after fectch data from mysql) to js extenal file. So if I use echo $x_1 it can pass to #watts_value in html file and display normally.

But I want to pass variable $x_1 to #watts_value and $x_2 to kwh_value. I already try to do that but it just pass all value to the #watts_value.

I have no idea about how to pass variable from php to javascript. Please suggest me or tell me how to do this.

This is my html

<div id="watts_value"></div>
<div id="kwh_value"></div>



This is my main.js

$(document).ready(function (){
 function read(){
  $.post("get_db.php", 
  function(data, status){
 
  if(status == 'success'){
   $('#watts_value').html(data);
  }
  else{
   $('#info').html("Error!");
  }
  });
 };
 read();
 setInterval(read,1000);
    });


This is my php file

<?php
$servername="localhost";
$username="root";
$password="";
$dbname="rt_db";
$tbname="rt_data";

$conn=new mysqli($servername, $username, $password, $dbname);
if($conn->connect_error){
    die("Connection failed: ".$conn->connect_error);
}


$sql_1="SELECT * FROM $tbname WHERE SensorId ='1'";
$sql_2="SELECT * FROM $tbname WHERE SensorId ='2'";

$result_1=$conn->query($sql_1);
$result_2=$conn->query($sql_2);

if($result_1->num_rows>0){
    while($row=$result_1->fetch_assoc()){
        $x_1=$row['SensorData'];
        echo $x_1;
    }
}
if($result_2->num_rows>0){
    while($row=$result_2->fetch_assoc()){
        $x_2=$row['SensorData'];
        echo $x_2;
    }
}

else {
    echo "fail";
}

$conn->close();
?>
Nothingnez
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  • You should look up the `IN` clause, as in `WHERE SensorId IN (1,2)` instead of running two separate queries. – tadman Apr 16 '17 at 18:46
  • **WARNING**: Using the error-suppressing `@` operator obscures problems with your code and makes debugging issues like this a whole lot more complicated. That's a tool of last resort and should only be used in exceptional circumstances. – tadman Apr 16 '17 at 18:47

4 Answers4

0

Use json_encode() in PHP to output a JSON string of an array. Then you can output the result on client side to see the response. It should be a javascript object.

TurtleTread
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0

you can put the values you need to pass through a request to an array, json encode it and echo it.

you may find the following thread useful.

Returning JSON from a PHP Script

Hope this helps. :)

Community
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Bhanuka Mahanama
  • 143
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0

The result of your request returns both @$x_1 and @$x_2 as one string. You can return JSON object with keys for x_1 and x_2

Oleksandr Matviichuk
  • 114
  • 5
  • Yes, JSON is the answer, thank you for your help. :) I will remember that if different variable want to passes, we must use JSON. – Nothingnez Apr 17 '17 at 06:45
0

I would suggest to create a JSON response to grab the different 'variables':

$jsonObject = ['WattsValue' => [], 'KwhValue' => []];

while($row = $result_1->fetch_assoc()){
    $jsonObject['WattsValue'][] = $row['SensorData'];
}

while($row = $result_2->fetch_assoc()){
    $jsonObject['KwhValue'][] = $row['SensorData'];
}

$conn->close();

header('Content-Type: application/json');
echo json_encode($jsonObject);
http_response_code(200);
exit;

When using jQuery, it'll recognize this as being JSON and giving the ability to use the JSON object directly:

$.post("get_db.php", 
    function(data, status){

    if(status === 'success'){
        $('#watts_value').text(data.WattsValue.join(','));
        $('#kwh_value').text(data.KwhValue.join(','));
    }
});
Dygnus
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  • This work for my case, you saved my day. Thank you so much. :) – Nothingnez Apr 17 '17 at 06:38
  • I confused that how to use these 2 variables `$jsonObject['WattsValue'][]` and `$jsonObject['KwhValue'][]` in highchart. I placed that 2 vars in my highchart but it can't work. – Nothingnez Apr 17 '17 at 12:00