Posted by Daz on 02/25/07 16:30

On Feb 25, 4:17 pm, Jerry Stuckle <jstuck...@attglobal.net> wrote:
> Daz wrote:
> > On Feb 25, 3:41 pm, "Daz" <cutenfu...@gmail.com> wrote:
> >> Hi everyone.
>
> >> I am trying to create an extension of the mysqli class within PHP, and
> >> I am finding it quite difficult. I am fairly new to PHP classes, and
> >> decided to give them a go. Here's what I have to far:
>
> >> <?php
> >> class sql_db extends mysqli
> >> {
> >> var $connection = false;
> >> function sql_db($username, $password, $database="",
> >> $server="localhost")
> >> {
> >> $this->connection = new mysqli($server, $username,
> >> $password, $database);
> >> if (mysqli_connect_errno()) {
> >> printf("Connect failed: %s\n",
> >> mysqli_connect_error());
> >> exit();
> >> }
> >> return = $this->connection;
> >> }
> >> }
> >> ?>
>
> >> All I am trying to achieve for now is for a simple error to be printed
> >> if the connection to the database fails. Rather than have error
> >> checking for each within each PHP file, I would just like to have it
> >> all done systematically. I would also like to add a few of my own
> >> methods, such as having the object pass back a PHP array, rather than
> >> a MySQL array. I know I can do this with a separate function, but
> >> really I am doing this for the learning experience more than anything.
>
> >> At the present time, this works:
>
> >> $db =& new sql_db("myUsername", "myPass", "someDB");
>
> >> But as soon as I try to query a table, like so:
>
> >> $res = $db->query("SELECT * FROM `some_table`;");
>
> >> I get:
>
> >> Warning: mysqli::query(): Couldn't fetch sql_db in - on line 21
>
> >> Evidently I am doing something wrong, and I would really appreciate
> >> any pointers. I suspect that I can't actually do what I want to do,
> >> although I can't see why not. In any case, I am sure it's possible,
> >> but I am going about it completely wrong.
>
> >> Thanks in advance.
>
> >> Daz.
>
> > OK, I've done some more thinking, and I think that what I am trying to
> > do, would involve overriding the constructor of the mysqli class,
> > which I guess wouldn't be wise, and might not even be possible.
>
> > Is there any way to override the contructor and find out what the
> > constructor code is? I guess that it wouldn't be a PHP class as such,
> > but more of a hybrid, but I am uncertain.
>
> > I can see that what I am doing is correct for adding extra functions,
> > but I would appreciate it if anyone can help me figure out the best
> > way to do some error checking when the connection is opened.
>
> > I would also appreciate any input on overriding the default methods,
> > i.e whether it's possible or not, or whether it's ill advised, or if I
> > can actually use the original constructor and carefully modify it.
>
> > I think the initial error checking might require an external function
> > which instantiates the class, and does the checking, then returns the
> > mysqli object if all went well, or returns false if it didn't.
>
> Daz,
>
> Overriding the constructor is quite common. But you need to ensure you
> also call the parent class constructor.
>
> As to seeing the code - it's like anything else in PHP. If it's a PHP
> file, you can see the code. If, like with mysqli, it's a compiled
> extension, you need to look at the source code for the extension.
>
> If you want some error checking when you open the connection, see if the
> connection is open after calling the mysqli constructor (see if
> mysqli_connect_error() is non-zero).
>
> You don't need an external function - you just need to check for errors.
> And if you don't want to keep checking the responses, check you
> exception handling.
>
> --
> ==================
> Remove the "x" from my email address
> Jerry Stuckle
> JDS Computer Training Corp.
> jstuck...@attglobal.net
> ==================


Thanks for that Jerry. You're a star! :)

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