Introduce capabilities for adding new posts

[nacin]

Many plugins need to be able to deny the creation of new items, particularly for CPT use cases. Unfortunately this is not easy to do.

I am suggesting a new cap for adding posts. Obviously, this has the potential to break quite a number of custom roles, but I think we can avoid that.

Instead, it would by default simply map to edit_posts. It wouldn't actually get assigned to any roles, so it's more or less a meta cap. (Only, without an $id, because it'd be a new post even pre-auto-draft in some cases.) But it then opens up the ability for this to be filtered by a plugin.

We could also potentially add this to the CPT capabilities array, but with the default being 'add_posts' => 'edit_posts'. Ultimately there are a few ways to implement this.

Ideally, the cap should be used for the admin menu, for post-new.php, for the 'Add New' button (no more clunky hiding it via CSS), XML-RPC, and the post handler for post-new.

+1 - The bbPress plugin and future BuddyPress versions will need to take advantage of something like this.

+1 as well.

Related: #16808

+10
current it is many code for add own caps; a example

			foreach ( $snippet_roles as $snippet_role ) {
				$wp_roles->add_cap( $snippet_role, 'edit_' . $this->post_type_1 );
				$wp_roles->add_cap( $snippet_role, 'edit_' . $this->post_type_1 . 's' );
				$wp_roles->add_cap( $snippet_role, 'edit_others_' . $this->post_type_1 . 's' );
				$wp_roles->add_cap( $snippet_role, 'publish_' . $this->post_type_1 . 's' );
				$wp_roles->add_cap( $snippet_role, 'read_' . $this->post_type_1 );
				$wp_roles->add_cap( $snippet_role, 'read_private_' . $this->post_type_1 . 's' );
				$wp_roles->add_cap( $snippet_role, 'delete_' . $this->post_type_1 );
				$wp_roles->add_cap( $snippet_role, 'manage_' . $this->taxonomy_type_1 );
			}
			
			$wp_roles->add_cap( 'author', 'read_' . $this->post_type_1 );
			$wp_roles->add_cap( 'contributor', 'read_' . $this->post_type_1 );
			$wp_roles->add_cap( 'subscriber', 'read_' . $this->post_type_1 );

Introducing add_posts with defaulting to edit_posts sounds pretty straight forward to me. Should not only make the menu more modular.

The add_post capability could also be used instead of "> level_0" hack we use in the author dropdowns. See #16841

+1

By the way, I think 'create_posts' would be a more intuitive name.

Ill Take this one on if noone minds :)

First draft diff attached.

Some cleaning up and readability while I was looking at the files

Also is there any use case for create_links?

Cheers
Ben

Initial Attempt

I think it would be best if we completely ignore create_links and co.

Also, please refrain from doing whitespace cleanup that isn't directly related to this ticket, especially considering we don't have a standard for that yet:

​http://wpdevel.wordpress.com/2011/04/04/to-the-directors-of-white-space/

Is the post creation capability to be governed independent of post editing? If so, the admin menu for each post type will need to be displayed if the user has edit_posts OR create_posts. But the current API only supports one required cap per menu:

$menu[5] = array( __('Posts'), 'edit_posts', 'edit.php', '', 'open-if-no-js menu-top menu-icon-post', 'menu-posts', 'div' );

$menu[20] = array( __('Pages'), 'edit_pages', 'edit.php?post_type=page', '', 'menu-top menu-icon-page', 'menu-pages', 'div' );

$menu[$ptype_menu_position] = array( esc_attr( $ptype_obj->labels->menu_name ), $ptype_obj->cap->edit_posts, "edit.php?post_type=$ptype", '', 'menu-top menu-icon-' . $ptype_class, 'menu-posts-' . $ptype_for_id, $menu_icon );

foreach ( $menu as $id => $data ) {
	if ( ! current_user_can($data[1]) )
		$_wp_menu_nopriv[$data[2]] = true;

@casben79: Cool. By the way, you have some property changes that should be removed before uploading a patch.

@kevinB: That's a very good question.

Actually, the way casben79 did it, create_posts requires you have the edit_posts capability, which seems logical to me, so it shouldn't be a problem.

@kevinb: Interesting thought, this could be useful for plugin / theme authors as well.

//Guilty untill proven innocent?
    $_wp_menu_nopriv[$data[2]] = true;
    if( is_array( $data[1] ) ){
	foreach( $data[1] as $cap ){
	    if( current_user_can( $cap ) ){
		unset( $_wp_menu_nopriv[$data[2]] );
	    }
	}
    } else {
	if ( current_user_can($data[1]) )
		unset( $_wp_menu_nopriv[$data[2]] );
    }

And then:

$menu[5] = array( __('Posts'), array( 'edit_posts' , 'create_posts' ) , 'edit.php', '', 'open-if-no-js menu-top menu-icon-post', 'menu-posts', 'div' );

What do you think?

Replying to scribu:

Actually, the way casben79 did it, create_posts requires you have the edit_posts capability, which seems logical to me, so it shouldn't be a problem.

I can imagine implementations that would appreciate enabling users to create a post via Quick Press or custom UI without being able to further edit the new draft. As I read it, the current patch actually does support that.

Don't forget there's a difference between 'edit_posts' and 'edit_others_posts'

Most of my neat formatting removed and create_links and co removed

Replying to casben79:

@kevinb: Interesting thought, this could be useful for plugin / theme authors as well.

//Guilty untill proven innocent?
    $_wp_menu_nopriv[$data[2]] = true;
    if( is_array( $data[1] ) ){
	foreach( $data[1] as $cap ){
	    if( current_user_can( $cap ) ){
		unset( $_wp_menu_nopriv[$data[2]] );
	    }
	}
    } else {
	if ( current_user_can($data[1]) )
		unset( $_wp_menu_nopriv[$data[2]] );
    }

And then:

$menu[5] = array( __('Posts'), array( 'edit_posts' , 'create_posts' ) , 'edit.php', '', 'open-if-no-js menu-top menu-icon-post', 'menu-posts', 'div' );

What do you think?

I think supporting creation-only usage of the full post edit form would be nice. But that would take some work in post.php also. At the very least you would need to redirect back to the dashboard following post creation. But wouldn't there also be some complications (edit_posts cap checking) due to auto-creation of new posts?

As the patch stands now, a user with create_posts (but not edit_posts) sees no "Add New" menu link but can still access post-new.php by direct URL.

Using Members Plugin, Changed the administrator to HAVE create_posts and NOT edit_posts and got "You do not have sufficient permissions to access this page."

create_posts is literally mapping directly to edit_posts, with map_meta_cap filter it could be changed to almost anything.

Need this for #21391.

16714.2.diff​ has some problems in map_meta_cap(). Rather than mapping to 'edit_posts', it should map to post_type_object->cap->edit_posts.

Bonus: It should instead map to cap->create_posts, and in get_post_type_capabilities(), cap->create_posts should be set to 'edit_' . $plural_base by default, essentially mapping it on the fly to edit_posts.

Both of these work only if we know the post type. So, we'll probably need to clarify that this can only be used like this:

if ( current_user_can( 'create_post', $post_type ) (or 'create_posts').

If used directly, as in $post_type_object->cap->create_posts, then $post_type isn't necessary. Attached is my thought process so far.

Since we need this, it gets saved by freeze. Would like someone to weigh in on 16714.3.diff​. We don't really have a similar half-primitive, half-meta capability implementation in core, so the approach could use a critique.

I don't see why we need 'create_posts' in 'map_meta_cap'. We should just make sure that $post_type_object->cap->create_posts is always set.

Or just get rid of 'create_post', since it doesn't accept a post id, like 'edit_post' or 'delete_post', so it shouldn't be singular.

Looks good. I'm indifferent to whether create_post stays or goes.

16714.4.diff​ gets rid of 'create_post' and uses 'create_posts' in wp-admin/menu.php.

Will be a little trickier for custom post type menus.

In [22060]:

Introduce create_posts meta capability. Props scribu, nacin, casben79. see #16714

​[UT1054]

#21463 was marked as a duplicate.

In the end, we actually did not need this for #21391. media.php happens to be accessible without upload_files, but it's a fluke — the Media Library (including the list table at upload.php) is entirely disabled for users who cannot upload files.

add-new.diff with some additions

Custom edit_posts should be used for create_posts if create_posts not specified

[22291]

​[UT1091]

We're still using edit_posts instead of create_posts in a couple of places for CPTs. Patch incoming.

16714.7.diff​ fixes two issues:

• Users who have the 'edit_posts' capability but not the 'create_posts' capability still see the 'Add New Post' menu in the admin toolbar. This applies to the 'create_posts' meta capability for all post types.
• Users who have the 'create_posts' meta capability but not the 'edit_posts' meta capability for a custom post type still see the 'Add New' submenu for the post type in the main menu.

In 22900:

Use create_posts whenever linking to post-new.php. props johnbillion. fixes #16714.

Dammit, missed a couple more. Patch incoming.

16714.8.diff​ fixes the cap check for the 'New Post' link in each item of the 'My Sites' menu.

Nacin and I are currently discussing a separate issue with 'create_pages' on IRC.

16714.9.diff​ corrects the check for 'create_pages' in map_meta_cap() and uses this cap in the admin menu.

16714.10.diff​ adds 'create_post' cap checks into the XML-RPC API where necessary. Props to markoheijnen for pointing this out.

Remove the awkward meta cap, which isn't filterable anyway, because most references are to the post type object.

In 22908:

Use the create_posts post type cap in more places. Remove the janky create_posts meta cap. see #16714.

I'd like to just get a little testing/review on [22908].

After all that, we should probably do 16714.12.diff​... It's not actually necessary because the current cap checks for upload.php (the list table) and the menu items all use upload_files. Only media.php?action=edit&attachment_id= and post.php?action=edit&post= are accessible without upload_files, and not directly through the UI (best I can tell), as long as you can edit that attachment using the standard edit_post cap tree.

In that case, we do an upload_files check on media.php for "Add New". We don't for post.php — that was the point of create_posts. So, 16714.12.diff​.

There's a unit test failure, even with .12.diff.

1) Tests_User_Capabilities::test_post_meta_caps
Failed asserting that false is true.

/.../unit-tests/trunk/Tests/User/Capabilities.php:490

In ​[UT1159]: Update capabilities test to reflect that create_posts is not a real cap, but rather an alias on the post type object.

​[UT1160]: Basic tests for the attachment post type having a different capability for create_posts than edit_posts.

This test fails without the final patch here.

Looks good.

In 22921:

Map the create_posts post type cap to upload_files for attachments.

Props nacin
fixes #16714

You may also wish to check file index.php in the TwentyTwelve theme. This makes use of current_user_can('edit_posts') to output a different message so that suitably empowered users can quickly add a first post to their blog.

Replying to mdgl:

You may also wish to check file index.php in the TwentyTwelve theme.

create_posts meta capability is new in 3.5. I guess Twenty Twelve should be left as is, since it's also supposed to work with 3.4.

I agree, no reason to touch 3.5.

The idea of blocking someone from creating posts of the "post" post type is still very nascent anyway.