Question

I am using MySQL to build a messaging system. Everything works beautifully so far but I need to be able to do one particular thing.

In one of the tables I have the column ‘sender_id’.

I take this ‘sender_id’ and run it through a function which then retrieves the users avatar and outputs the link in the returned JSON response.

I need this link… But I also need to be able to retrieve the ‘sender_id’ itself as a number so that I can test against it in jquery.

So what I ultimately what is for the originaly ‘sender_id’ to be duplicated and put into a kind of virtual column ‘before’ it has been processed by my ‘get avatar’ function.

The code I am using to output the JSON after the queries etc. is as follows:-

/*
     * Output
     */
    $output = array(
        "sEcho" => intval($_GET['sEcho']),
        "iTotalRecords" => $iTotal,
        "iTotalDisplayRecords" => $iFilteredTotal,
        "aaData" => array()
    );

    while ( $aRow = mysql_fetch_array( $rResult ) )
    {
        $row = array();
        for ( $i=0 ; $i<count($aColumns) ; $i++ )
        {
            if ( $aColumns[$i] == "version" )
            {
                /* Special output formatting for 'version' column */
                $row[] = ($aRow[ $aColumns[$i] ]=="0") ? '-' : $aRow[ $aColumns[$i] ];
            }
            if ( $aColumns[$i] == "sender_id" )
            {
                /* Special output to render Avatar by user id */
                $row[] = commentplayer_get_user_avatar($aRow[ $aColumns[$i] ]);

            }
            else if ( $aColumns[$i] == "message" )
            {
                /* General output */
                $row[] = strip_slashes($aRow[ $aColumns[$i] ]);
            }

            else if ( $aColumns[$i] != ' ' )
            {
                /* General output */
                $row[] = $aRow[ $aColumns[$i] ];
            }
        }
        $output['aaData'][] = $row;
    }

    echo json_encode( $output );
?>

$aColumns is the array of columns which are defined earlier, obviously ‘sender_id’ is one of these. As you can see I have put in a conditional statement so that the sender_id is retruned as an avatar link rather than the actual sender_id. So to sumarise I just need to be able to pull the actual sender_id out aswell as the avatar, preferably into a separate column.

Any ideas?

Answer 1

You can add a line to the code handling the column sender_id:

        if ( $aColumns[$i] == "sender_id" )
        {
            /* Output user id */
            $row[] = $aRow[ $aColumns[$i]] );
            /* Special output to render Avatar by user id */
            $row[] = commentplayer_get_user_avatar($aRow[ $aColumns[$i] ]);

        }

This will insert the user id right before the avatar URL in each returned JSON row-array.

In fact, it would be nicer to get rid of the for-loop over the columns, and just fill $row with the items you need, indexed by proper names instead of depending on the order. This makes it easier to see what is actually appended to $output. It does mean that when interpreting the JSON on the client, you will have to treat the row as an object rather than an array.

    $row = array(
        "version"   => ($aRow["version"] == "0") ? '-' : $aRow["version"],
        "sender_id" => $aRow["sender_id"],
        "avatar"    => commentplayer_get_user_avatar($aRow["sender_id"]),
        "message"   => strip_slashes($aRow["message"]),
        // other items here
    );