Automate database table creation from within CakePHP framework

Question

I'm trying to write a webapp with CakePHP, and like most webapps I would like to create an installer that detects whether the database has been initialized and, if not, executes the installation process.

This process will be entirely automated (it assumes the database itself already exists, and that it is granted full administrative access through the anonymous account with no password...this is for a sandbox environment, so no worries about security), so it needs to be able to detect (regardless of the request!) if the database tables have been created and initialized, and if not, to perform that initialization transparently and then still serve up the user's original request.

I considered writing a sort of Bootstrap controller through which all requests are routed, and a single SQL query is run to determine if the database tables exist, but this seemed cumbersome (and the controller requires a corresponding model, which needn't be the case here). The other possibility is was to override AppModel and place within it the same test, but I was unsure how to do this, as there isn't any documentation along these lines.

Thanks in advance!

tl;dr version: What is the CakePHP equivalent (or how can the equivalent be written for CakePHP) of a J2EE servlet's "init()" method?

Answer 1

Check out the AppError class - may be there is a missing database table error that your can override and run your create database table SQL from there?

Answer 2

Something like this might do what you're looking for, but does require an extra query per model.

<?php
class AppModel extends Model {
    var $create_query = false;

    function __construct($id = false, $table = null, $ds = null) {
        parent::__construct($id, $table, $ds);

        if (!empty($this->create_query)) {
            $this->query($this->create_query);
        }
    }
}
?>

Then you would just need to add var $create_query = 'CREATE TABLE IF NOT EXISTS ...;` in your models. The MySQL CREATE TABLE documentation has more information on IF NOT EXISTS.

However, I'm not certain that this isn't trying to call query() too early. Or before the check to see if the table already exists, which it would have to be. Otherwise, CakePHP would error out instead of creating your table. There isn't much documentation on the subject and your best bet for more information going to be to take a look at cake/libs/model/model.php directly.

Update: The code above would not work as written.

After looking into the Model class a little deeper, Model::__construct calls Model::setSource(). Model::setSource() checks to see if the table exists and throws an error if it doesn't. To use this method, that's where you'd have to override and insert the query. The code below may need to differ, depending on which version of CakePHP you're using.

<?php
function setSource($tableName) {
    // From Model::setSource().  I believe this is needed to make query() work.
    $this->setDataSource($this->useDbConfig);

    // Create our table if we have a create query
    if (!empty($this->create_query)) {
        $this->query($this->create_query);
    }

    // Now call the parent
    parent::setSource($tableName);
}
?>