Add function to check if current page is a custom post type

[sirzooro]

From #9674:

There is one important piece missing, as Denis-de-Bernardy pointed earlier:

Following up on the previous remark... some kind of is_custom() function would be useful, and a means to bypass the WP query entirely in the workflow immediately after the query is parsed. else WP_Query may get loaded with junk. init_query_flags() for instance, probably also needs some reference to is_custom = false. after parse_query is done, $wp_query filters itself through do_action_ref_array(), and if it ends up with is_custom set to true at that stage, the actual WP query gets skipped entirely -- WP should then make the assumption that it has been set up already. I don't think we actually need anything in the template loader, since there is a hook in there already. But there definitely needs something over in the wp_query query class to go something like: please bail the WP query.

I would like to see function with following declaration, in order to be able to check if current page belongs to given post type and/or give list of custom posts to test against:
function is_custom( $post_type = '', $post_id = '' )

[rmccue]

nacin's patch, plus a workaround for get_post_type() bug

[rmccue]

Once #12827 is fixed, we can remove the default for $id lines.

[blepoxp]

Removed lines for id and change default id from null to false so it would work with get_post_type

[blepoxp]

Was looking through tickets, saw that other ticket was closed.
Removed lines per ryan's note, tested, changed $id=null to $id=false so it is compatible with get_post_type($the_post=false)

Let me know if anything else needs changed.

[sirzooro]

I would like to be able to check if current page is of any registered post type. I have modified last patch a bit - with my change 1st function parameter is optional too and defaults to all registered post types.

[sirzooro]

Default 1st param to all post types

[nacin]

(In [14158]) Introduce is_post_type(). Can check if a post type is registered, or also if a post (current or specified) is of a certain post type. fixes #12588, props sirzooro, blepoxp, rmccue

[scribu]

is_post_type() doesn't work when trying to "Checks if a post type is registered":

function _debug() {
    var_dump(is_post_type('post'), (bool) get_post_type_object('post'));
}
add_action('init', '_debug', 100);

You get bool(false) bool(true).

[scribu]

is_post_type.diff first checks if the $id parameter is set.

[nacin]

(In [14498]) Fix to is_post_type. props scribu, fixes #12588.

[chrisscott]

As originally committed and documented in [14158] this function defaulted to the current post ID if it wasn't passed. That's now changed in [14498]. This seems like a bug since the original commit and subsequent patches retained/fixed that functionality.

[scribu]

Then the documentation should be updated to reflect that is_post_type() only checks if a post if of a certain type.

[scribu]

Maybe have two functions:

is_post_type() - check if a post type is registered

is_post_of_type() - check if a certain post is of a certain type

[nacin]

Replying to scribu:

Maybe have two functions:

Sounds good. I've apparently been grasping at straws here.

[scribu]

introduce is_post_of_type()

[sirzooro]

I agree, new approach is much better.

BTW, please make sure is_post_of_type() will return false when called from non-post pages (e.g. home page, category or date archive). I am going to test this within few next days and will let you know if there are any issues.

[sirzooro]

One more thing: previous function version allowed to skip $types param, and uses all post types (returned by get_post_types()) as default. Please change is_post_of_type() to follow this.

[scribu]

Replying to sirzooro:

BTW, please make sure is_post_of_type() will return false when called from non-post pages (e.g. home page, category or date archive). I am going to test this within few next days and will let you know if there are any issues.

Why?

One more thing: previous function version allowed to skip $types param, and uses all post types (returned by get_post_types()) as default. Please change is_post_of_type() to follow this.

I disagree. It's meant to check agains specific post types; that's why it's called is_post_of_type() you know...

[sirzooro]

Replying to scribu:

Replying to sirzooro:

BTW, please make sure is_post_of_type() will return false when called from non-post pages (e.g. home page, category or date archive). I am going to test this within few next days and will let you know if there are any issues.

Why?

I would like to use following code in plugin:

if ( is_post_of_type( 'mytype' ) {
  do_something_special();
}

I think other people would like to do the same.

One more thing: previous function version allowed to skip $types param, and uses all post types (returned by get_post_types()) as default. Please change is_post_of_type() to follow this.

I disagree. It's meant to check agains specific post types; that's why it's called is_post_of_type() you know...

I need this to do some things for all post types, e.g. print meta headers in <head>, which are stored as post meta data. The easiest way would be to just check if is_post_of_type() will return true. But this is not a problem - I can use is_post_of_type( get_post_types() ) instead.

[scribu]

I think I understand what you're getting at:

Rather than checking if a post type is registered, you want is_post_type() to act like a conditional tag.

IMO, we should add a $post_type parameter to is_singular() instead.

[scribu]

add $post_type parameter to is_singular()

[scribu]

Replying to sirzooro:

One more thing: previous function version allowed to skip $types param, and uses all post types (returned by get_post_types()) as default. Please change is_post_of_type() to follow this.

I disagree. It's meant to check agains specific post types; that's why it's called is_post_of_type() you know...

I need this to do some things for all post types, e.g. print meta headers in <head>, which are stored as post meta data. The easiest way would be to just check if is_post_of_type() will return true. But this is not a problem - I can use is_post_of_type( get_post_types() ) instead.

You should be able to use is_single() instead. From the doc:

 * This applies to other post types, attachments, pages, posts. Just means that
 * the current query has only a single object.

[scribu]

add $post_type parameter to is_singule()

[scribu]

preserve old behaviour of is_singular() when not passing a post type

[nacin]

Aligns is_post_type and is_post_type_hierarchical with the taxonomy counterparts.

[nacin]

(In [14521]) Simplify is_post_type and is_post_type_hierarchical. Make them work like their taxonomy counterparts. see #12588.

[scribu]

check $wp_query->is_single too

[scribu]

Refreshed patch: is_singular.3.diff

[nacin]

I'm game for is_singular, though I'm confused -- why are we now also checking is_single?

[scribu]

Because we want is_singular('book') to return true only when there's a single book being displayed.

[scribu]

And, as somebody in IRC mentioned, we should also have is_archive('book'), to complement is_singular('book').

[scribu]

Having is_post_type() and is_taxonomy() is confusing, since the is_*() functions are expected to be conditional tags. I think we should rename (deprecate) them:

is_taxonomy() -> taxonomy_exists()

is_taxonomy_hierarchical() -> hierarchical_taxonomy_exists()

is_post_type() -> post_type_exists()

is_hierarchical_post_type() -> hierarchical_post_type_exists()

[ryan]

If page is passed, then the is_single check will cause false to always be returned, it seems. I think it should return immediately if ->is_singular is false or if post_types is empty. Otherwise return the result of in_array().

[ryan]

Something like that (not completely tested).

[nacin]

(In [14887]) Give is_singular the ability to provide awareness/context for custom post types. props ryan, scribu. Usage: is_singular('book') or is_singular( array( 'newspapers', 'books' ) ). fixes #12588.