Re: Extra Data in POST response

On 12/02/2023 22:29, John Iliffe wrote:
> On Sun, 2023-02-12 at 21:15 +0000, Ashley Sheridan wrote:
>> On 12/02/2023 19:49, John Iliffe wrote:
>>> I seem to be getting extraneous data in the response sent to the browser by PHP.
>>>
>>> The server query is an AJAX request in json format which is received and
>>> processed correctly and the result is sent using the "echo" function.  I have
>>> checked and the area where the response is constructed is empty when processing
>>> starts.
>>>
>>> The data received by the browser has BOTH the request json data followed by the
>>> correct response in the received string (result not HTML, just a string that
>>> will eventually be converted to json but so far will only be caught in the
>>> browser for display).
>>>
>>> I'm using XMLHttpObject in the browser and I haven't been able to find a way to
>>> separate the request from the response.  Before I construct an elegant
>>> workaround does POST normally return the request?  If not, what am I doing
>>> wrong?  So far I have always used GET so I know it doesn't return the request.
>>>
>>> For completeness, here is what the server says it is sending to the browser
>>> (using echo) (The json may be wrong; I'm still just trying to receive it).
>>>
>>> ------
>>> sent to browser:
>>> "jres":[{"item_id":"5","i_type":"OL","i_name":"Student Success
>>> Pages","i_stock":"99924","i_price":"14.00","i_books_box":"0"},{"item_id":"13","i
>>> _type":"CD","i_name":"Basic Instructors Guide 9th
>>> Ed.","i_stock":"9983","i_price":"19.95","i_books_box":"0"},{"item_id":"20","i_ty
>>> pe":"SG","i_name":"Canadian Amateur Radio Basic Qualification Study
>>> Guide","i_stock":"274","i_price":"44.95","i_books_box":"20"},{"item_id":"21","i_
>>> type":"SG","i_name":"Canadian Amateur Radio Advanced Qualification Study
>>> Guide","i_stock":"1586","i_price":"49.95","i_books_box":"16"}]
>>> -----
>>>
>>> here is the original request from the browser, as decoded by server
>>> ------
>>> request method: POST
>>> requests: array (
>>>     'req' => '{"func":"act","item":"438"}',
>>> )
>>>
>>> json last error message: No error
>>> decoded_args:
>>>      func=act
>>>      item=438
>>>
>>> -------
>>>
>>> and here is what the browser says it received back:
>>>
>>> -----
>>>    received:-->array(2) {
>>>     ["func"]=>
>>>     string(3) "act"
>>>     ["item"]=>
>>>     string(3) "438"
>>> }
>>>
>>> "jres":[{"item_id":"5","i_type":"OL","i_name":"Student Success
>>> Pages","i_stock":"99924","i_price":"14.00","i_books_box":"0"},{"item_id":"13","i
>>> _type":"CD","i_name":"Basic Instructors Guide 9th
>>> Ed.","i_stock":"9983","i_price":"19.95","i_books_box":"0"},{"item_id":"20","i_ty
>>> pe":"SG","i_name":"Canadian Amateur Radio Basic Qualification Study
>>> Guide","i_stock":"274","i_price":"44.95","i_books_box":"20"},{"item_id":"21","i_
>>> type":"SG","i_name":"Canadian Amateur Radio Advanced Qualification Study
>>> Guide","i_stock":"1586","i_price":"49.95","i_books_box":"16"}]<--
>>> -----
>>>
>>> Thanks in advance for any suggestions you can give.
>>>
>>> John
>>> ======
>> Hi John,
>>
>> What does your PHP code look like? Something in it must be outputting
>> the request, as that's not something that would just occur all by itself.
>>
>> Regards,
>> Ash
> Thanks for the quick response Ash.  That's what I have been asking myself and I
> wondered if returning the query is a requirement of the POST protocol.  Without
> sending the entire script, I can say that there are only two "echo" statements
> in it (by doing a grep for echo) and they are mutually exclusive:
>
> -----
> [John@prod04 test]$ grep -n echo ./XXXXXXb.php
> 140:   echo $json_resp;
> 145:   echo "<br />XXXXXb: Either func or item was not set<br />err is true,
> errno=" . $errno . "<br />";
> -----
> <?php
> ob_start();
> /* XXXXXXb responds to AJAX inventory report requests
>   * from updated XXXXXXXX.
>   *
>   * Written J Iliffe 2/2023
>   * copyright John Iliffe, 2023, all rights reserved.
>   */
> //header('Content-Type: application/json; charset=utf-8');
> header('Content-Type: text/plain; charset=utf-8');
> $func = "";
> $item = 0;
> $err = false;
> $errno = 0;
>
>          $fx = fopen("/tmp/XXXXXb.txt","w");
>
>          fwrite($fx,("\nrequest method: " . $_SERVER['REQUEST_METHOD']));
>          fwrite($fx,("\nrequests: " . var_export($_REQUEST,true)));
>
> /* get the json request block as associative array */
> if (isset($_POST['req']))
>    {
>     $decoded_args = json_decode($_POST['req'],true,5,JSON_INVALID_UTF8_IGNORE);
>
>     if ((isset($decoded_args['func'])) && (isset($decoded_args['item'])))
>       {
>        $func = $decoded_args['func'];
>        $item = $decoded_args['item'];
>               fwrite($fx,("\nfunc and item isset as " . $func . " and " . $item .
> "\n"));
>       }
>     else
>       {
>        $err = true;
>        $errno = 2;
>       }
>
>          fwrite($fx,("\njson last error message: " . json_last_error_msg() .
> "\n"));
>          fwrite($fx,("decoded_args:" . var_dump($decoded_args) . "\n"));
>          fwrite($fx,("func=" . $decoded_args['func'] . "\n"));
>          fwrite($fx,("item=" . $decoded_args['item'] . "\n"));
>    }
> else
>    {
>     $err = true;
>     $errno = 1;
>    }
>
> /* if we are good to go here, open database, create query */
> $json_resp = '"jres":[';        //json opening
>
>     ----I deleted the database activity from here---
>
> if (! $err)
>    {
>     if (! $res)
>          {
>           $err=true;
>           $errno = 4;
>          }
>        else
>          {
>           for ($i=0;$i<$rows;$i++)
>            {
>              $r_arr = pg_fetch_array($res,null,PGSQL_ASSOC);
>
>              $json_rec=json_encode($r_arr,0,16);
>
>                  if ($json_rec === false)
>                    {
>                     fwrite ($fx,("\nrecord at " . $i . " bad, " .
> json_last_error_msg() . "\n"));
>                    }
>
>
>              if (($i < $rows) && ($i != 0))      // no opening or trailing ','
>                {
>                 $json_resp .= ',';
>                }
>
>              $json_resp .= $json_rec;
>             }
>
>           $json_resp .= ']';
>
> fwrite($fx,("\njson sent to browser:\n   -->" . $json_resp . "<---\n\n\n"));
>          }
>       }
>    }
>
> if (! $err)
>    {
>     echo $json_resp;
>     ob_flush();
>    }
> else
>    {
>     echo "<br />adm9005b: Either func or item was not set<br />err is true,
> errno=" . $errno . "<br />";
>     ob_flush();
>    }
>
> exit;
> ?>
> ------
>
> This is pretty much what I have so far and why it has been driving me nuts for
> several days now...the query is never repeated anywhere in the echoed output.
> What actually comes back to the browser, as you can see above, is is the result
> generated by this; prepended with PHP's analysis of the original POST query.
>
> Thanks for taking the time to look.
>
> John
> ======

It might be some error output, which is being supressed by the 
ob_start(), and then output when you do the ob_flush(). Why are you 
using those, as it's unusual for what you appear to be doing here.

Thanks,
Ash

-- 
www.ashleysheridan.co.uk