WHERE clause with PHP coming from Javascript

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I need to pass a variable from PHP in a clause WHERE of a SELECT, but this PHP variable gets a value from JAVASCRIPT.

I ran a test passing only a native PHP value and it worked:

<?php
$phpNum = 1;         /* Testando com numérico */ 
$phpTxt = 'teste';   /* Testando com texto    */
$sqlNum = mysqli_query($conn,"SELECT * FROM tab1 where campo ='".$phpNum."'");
$sqlTxt = mysqli_query($conn,"SELECT * FROM tab2 where campo ='".$phpTxt."'");
?>

Both selects worked perfectly!

Now if these PHP variables receive Javascript value, then the query fails. I’m getting the JS values as follows:

<script type="text/javascript">

var jsNum =  1;
var jsTxt = 'teste';

</script>

<?php 

$phpNum = '<script>document.write(jsNum)</script>';
$phpTxt = '<script>document.write(jsTxt)</script>';

/* Se testar a saída com um echo a saída acontece perfeitamente também */

$sqlNum = mysqli_query($conn,"SELECT * FROM tab1 where campo ='".$phpNum."'");
$sqlTxt = mysqli_query($conn,"SELECT * FROM tab2 where campo ='".$phpTxt."'");

/* Nesse momento que ocorre a falha da query, mesmo testando selects individualmente */

?>

How I can pass the correct JS value to PHP (numeric or text) so that this PHP variable can be correctly assigned in SELECT ???

php javascript html mysql select

  • you will have to make a "api" in php to receive ajax requests or whatever coming from javascript by POST/GET/PUT/DELETE and etc. Try a search on "restful".

  • 1

    If that’s what I’m thinking, it’s all literally wrong. Nothing makes sense. What is in Javascript is never read by PHP, so you can communicate Javascript with PHP you need to make a request, using AJAX, as mentioned above. This way you can send to a "page" the data that was generated or defined by Javascript.

  • Php can read JS yes. And for what I’m doing it has to be that way. Maybe just some conversion feature like JSON is missing.

  • There is no way PHP can read the javascript guy. Where did you see this? Javascript is a language that works ONLY there on the front end and php works there on the server, in the back end. It’s IMPOSSIBLE for him to read the javascript stuff the way you want. What you have to do is make REQUESTS for php sending the javascript data. Now php reading the javascript is clueless.

  • Because it’s a brother, but if you do so: $varPHP = '<script>Document.write(varJS)</script>'; You will see that it is possible yes...

  • I’ll ask otherwise then rsrsr. If I have a Javascript var X and want to pass it in the Where clause of this select, as I would then ?

  • 1

    Eduardo, understand this: php is interpreted by the server and javascript by the browser. Respect the order of things. First your code is interpreted by the server and after that returns to the browser, probably an HTML, and then your javascript code is interpreted by the browser. As they said above, search for the Rest and ajax api.

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The way you put it you will not be able to make it work because Javascript runs on the client side and not on the server side. One way you solve this is you receive these values with $_GET as in the example below

<?php
$phpNum = $_GET['phpNum'];    /* Testando com numérico */ 
$phpTxt = $_GET['phpTxt'];   /* Testando com texto    */
$sqlNum = mysqli_query($conn,"SELECT * FROM tab1 where campo ='".$phpNum."'");
$sqlTxt = mysqli_query($conn,"SELECT * FROM tab2 where campo ='".$phpTxt."'");
?>

Then you can run the above code by passing the values of phpNum and phpTxt via url: seuscript.php?phpNum=1&phpTxt=teste

This way yes you can receive by Javascript. You can use the utility $.ajaxjQuery library (read more on http://api.jquery.com/jquery.ajax/)

You can also search for acquisition ajax with Javascript.

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