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# Plug and Play Schema Information with Templates

Doctrine templates essentially allow you to extract schema information so that it can be plugged in to multiple Doctrine classes without having to duplicate any code. Below we will show some examples of what a template could be used for and how it can make your schema easier to maintain.

Let's get started. Imagine a project where you have multiple records which must have address attributes. Their are two basic approaches to solving this problem. One is to have a single table to store all addresses and each record will store a foreign key to the address record it owns. This is the "normalized" way of solving the problem. The "de-normalized" way would be to store the address attributes with each record. In this example a template will extract the attributes of an address and allow you to plug them in to as many Doctrine classes as you like.

First we must define the template so that we can use it in our Doctrine classes.

> class Doctrine_Template_Address extends Doctrine_Template { public

function setTableDefinition() { $this->hasColumn('address1', 'string', 255); $this->hasColumn('address2', 'string', 255); $this->hasColumn('address3', 'string', 255); $this->hasColumn('city', 'string', 255); $this->hasColumn('state', 'string', 2); $this->hasColumn('zipcode', 'string', 15); } }

Now that we have our template defined, lets define some basic models that need to have address attributes added to them. Lets start first with a User.

> class User extends Doctrine_Record { public function

setTableDefinition() { $this->hasColumn('username', 'string', 255); $this->hasColumn('password', 'string', 255); }

    public function setUp()
    {
        $this->actAs('Address');
    }

}

Now we also have a Company model which also must contain an address.

> class Company extends Doctrine_Record { public function

setTableDefinition() { $this->hasColumn('name', 'string', 255); $this->hasColumn('description', 'clob'); }

    public function setUp()
    {
        $this->actAs('Address');
    }

}

Now lets generate the SQL to create the tables for the User and Company model. You will see that the attributes from the template are automatically added to each table.

> CREATE TABLE user (id BIGINT AUTO_INCREMENT, username VARCHAR(255),

password VARCHAR(255), address1 VARCHAR(255), address2 VARCHAR(255), address3 VARCHAR(255), city VARCHAR(255), state VARCHAR(2), zipcode VARCHAR(15), PRIMARY KEY(id)) ENGINE = INNODB

CREATE TABLE company (id BIGINT AUTO_INCREMENT, name VARCHAR(255), description LONGTEXT, address1 VARCHAR(255), address2 VARCHAR(255), address3 VARCHAR(255), city VARCHAR(255), state VARCHAR(2), zipcode VARCHAR(15), PRIMARY KEY(id)) ENGINE = INNODB

That's it. Now you can maintain your Address schema information from one place and use the address functionality in as many places as you like.