[Ubuntu] How to the virtualhost to a path which has many project folder?

For example, i have there projects folders in

/var/www/project_1

/var/www/project_2

/var/www/project_3

In a common method, I have to set the virtualhost of the three projects  as:

<VirtualHost *:80>
    <Directory "/var/www/project_1">
    </Directory>

    DocumentRoot "/var/www/project_1"
    ServerName project_1.myhost
    ServerAlias project_1.myhost
</VirtualHost>
<VirtualHost *:80>
    <Directory "/var/www/project_2">
    </Directory>

    DocumentRoot "/var/www/project_2"
    ServerName project_2.myhost
    ServerAlias project_2.myhost
</VirtualHost>
<VirtualHost *:80>
    <Directory "/var/www/project_3">
    </Directory>

    DocumentRoot "/var/www/project_3"
    ServerName project_3.myhost
    ServerAlias project_3.myhost

</VirtualHost> 

But, the problem comes, how about the new projects coming? Copy and paste the code? No, that is no so clear to do that. We have to find a new way to do it. So how about the code, it help me much la!

VirtualDocumentRoot /var/www/%1
<VirtualHost *:80>
   DocumentRoot /var/www
   ServerName myhost

</VirtualHost> 

Then i can create any folder in /var/www, then view it directly with the folder name. For example, i create a folder /var/www/test, then i can view it via: http://test.myhost , that is cool!