How do I allow certain users to make a certain type of post?

Question

Here's a brief summary of how my site is setup:

I have a relatively simple Intranet site. Right now I am utilizing posts as a means to provide news to users. I am also using pages. I only want certain users to be able to do these things (let's say "Editors").

What I would like to do is to setup a community section of the site where all users are able to make a post (to sell things, etc). I am wondering what the best way to go about this is? I could use a category to make it easy to show only these types of posts. But, I don't want users to be able to make any type of post. I only want them to be able to post to the community. If someone is posting news, I want them to have a higher security level.

If I am thinking about this the wrong way, I'd love to hear other ideas!

Edit:

Here is my current custom post code:

function createCommunityPostType() {
    $args = array(
            'public' => true,
            'label' => 'Community'
    );
    register_post_type('community', $args );
}
add_action('init', 'createCommunityPostType');

Answer 1

The following will assign capability requirements to your CPT. So, users will require edit_community, delete_community etc capabilities to perform those actions.

function createCommunityPostType() {
    $args = array(
            'public' => true,
            'label' => 'Community'
            'capability_type' => 'community',
            'map_meta_cap' => true
    );
    register_post_type('community', $args );
}
add_action('init', 'createCommunityPostType');

See the parts about capabilities in the codex.

You also need to assign these caps to your users. You could use a plugin for this (see the members plugin), or you can do it yourself:

function my_after_setup_theme() {

    $role = get_role( 'subscriber' );
    $caps_set = get_option( 'my_caps_set' );
    if ( !$caps_set ) {
        $role->add_cap( 'edit_community' );
        $role->add_cap( 'read_community' );
        $role->add_cap( 'delete_community' );
        // ... and so forth (see codex for caps list)

        update_option( 'my_caps_set', true );
    }
}

add_action( 'after_setup_theme', 'my_after_setup_theme' );

We set a settings flag to save from resetting the caps more than once.

the above code assumes you want to assign these caps to subscribers, but you can change this to any role, or create your own role.