October CMS (Rainlab Blog) - Next and Prev Post link from same category - blogs

Question

I have a blog post page where I'm using the category as a hardcoded parameter in url.
The url is like
url = "/category1/:slug"
I'm using blogPost component in this layout.
I can get the nextPost and prevPost link using the following code in template
{% set nextPost = blogPost.post.nextPost %}
{% set prevPost = blogPost.post.previousPost %}
But I want to constraint nextPost and prevPost to be from same category as blogPost.post i.e. category1
blogPost.post belogs to only one category
I've checked that the Post model has a method scopeFilterCategories
but I'm not sure how to use it or if it serves the same purpose.
Code
This is the configuration part
title = "Category1 post"
url = "/category1/:slug"
layout = "default"
is_hidden = 0
robot_index = "index"
robot_follow = "follow"
[blogPost]
slug = "{{ :slug }}"
categoryPage = "category1"

Answer 1

It seems Thye are not Providing that Out of the box
I have created snippets which can do that work.
In you page's code block add this code snippet [ next previous works based on published_at field (Published on in form) ]
public function nextPost($post) {
// get current cats
$postCats = $post->categories->pluck('id')->toArray();
// Here you need to pass it as we are
// hardcoding category slug in URL so we have no data of category
// IF YOU DONT WANT CAT COME FROM POST
// YOU CAN HARD CODE THEM $postCats = ['2']
// here 2 is id of category
// use this cats to scope
$nextPost = $post->isPublished()->applySibling(-1)
->FilterCategories($postCats)->first();
// check if next is not availabe then return false
if(!$nextPost) {
return false;
}
// create page link here same page
$postPage = $this->page->getBaseFileName();
// set URl so we can direct access .url
$nextPost->setUrl($postPage, $this->controller);
// set Cat URl so we can use it directly if needed
$nextPost->categories->each(function($category) {
$category->setUrl($this->categoryPage, $this->controller);
});
return $nextPost;
}
public function previousPost($post) {
// get current cats
$postCats = $post->categories->pluck('id')->toArray();
// IF YOU DONT WANT CAT COME FROM POST
// YOU CAN HARD CODE THEM $postCats = ['2']
// here 2 is id of category
// use this cats to scope
$prevPost = $post->isPublished()->applySibling(1)
->FilterCategories($postCats)->first();
// check if nprevious ext is not availabe then return false
if(!$prevPost) {
return false;
}
// create page link here same page
$postPage = $this->page->getBaseFileName();
// set URl so we can direct access .url
$prevPost->setUrl($postPage, $this->controller);
// set Cat URl so we can use it directly if needed
$prevPost->categories->each(function($category) {
$category->setUrl($this->categoryPage, $this->controller);
});
return $prevPost;
}
In Markup area you can add this code.
{% component 'blogPost' %}
{% set nextPostRecord = this.controller.pageObject.nextPost(blogPost.post) %}
{% set previousPostRecord = this.controller.pageObject.previousPost(blogPost.post) %}
{% if previousPostRecord %}
Previous
{% endif %}
{% if nextPostRecord %}
Next
{% endif %}
This will respect category and show only that category posts
If any doubt please comment.