"filter[posts_per_page]" not affecting the "X-WP-TotalPages" response header #1876

Hi there,

I'm using filter[posts_per_page] to retrieve a collection of posts for my application. The problem I'm facing is that the filter[posts_per_page] parameter is not updating the X-WP-TotalPages header as returned in the response by the server.

However, if I use per_page parameter in the request, it's updating the X-WP-TotalPages accordingly.

Consider the following request to the server:

$ GET /wp/v2/posts?filter[posts_per_page]=5

The headers returned are as follows:

X-WP-Total → 45
X-WP-TotalPages → 5

Now if I use the per_page parameter like the following:

$ GET /wp/v2/posts?per_page=5

The headers returned are like the following:

X-WP-Total → 45
X-WP-TotalPages → 9

It can be seen that the later one updated the X-WP-TotalPages header accordingly.

I think that the X-WP-TotalPages should be updated whenever a request is made via filter[posts_per_page] parameter.