will_paginate JSON support?

I wonder if anyone could please tell me if will_paginate can support JSON out of the box or if this has to be hacked?

I would like to add page data to the JSON responses while will_paginate manages pagination.

Gem: will_paginate, version 3.1.8


def pagination_meta(collection)
{
current_page: collection.current_page,
next_page: collection.next_page,
prev_page: collection.previous_page,
total_page: collection.total_pages,
total_count: collection.total_entries,
} if collection.present?
end

**The easiest solution**

def index
@posts = Post.all.paginate(:page => params[:page], :per_page => 4)
render :json => @posts.to_json(:methods => [:image_url])
end

You just need to add `gem 'will_paginate'`

It works for me.

This one helps me:

Add this method to your base API controller.

def pagination_dict(collection)
{
current_page: collection.current_page,
next_page: collection.next_page,
prev_page: collection.prev_page, # use collection.previous_page when using will_paginate
total_pages: collection.total_pages,
total_count: collection.total_count # use collection.total_entries when using will_paginate
}
end

Then, use it on your render method.

render json: posts, meta: pagination_dict(posts)

**Adding Pagination to an API**

I found an easy solution to API Json Response Pagination with will_pagination.

start by creating a class method in `ApplicationController` that will create an `after_filter` that will set the pagination meta-data in the response headers:
>application_controller.rb

class ApplicationController < ActionController::Base

protected
def self.set_pagination_headers(name, options = {})
after_filter(options) do |controller|
results = instance_variable_get("@#{name}")
headers["X-Pagination"] = {
total: results.total_entries,
total_pages: results.total_pages,
first_page: results.current_page == 1,
last_page: results.next_page.blank?,
previous_page: results.previous_page,
next_page: results.next_page,
out_of_bounds: results.out_of_bounds?,
offset: results.offset
}.to_json
end
end

end


Then in the controller we want to add pagination headers we can call it like such:

>widgets_controller.rb

class Api::V1::WidgetsController < Api::V1::BaseController
set_pagination_headers :widgets, only: [:index]

def index
@widgets = Widget.all.paginate(params).order("created_at desc")
respond_with @widgets
end

end

response headers that look like this

> Cache-Control:max-age=0, private, must-revalidate
> Connection:keep-alive Content-Type:application/json; charset=utf-8
> Etag:"fe70f7bae4c6e5cdea7867aa7fc0c7b4"
> X-Pagination:{"total":14,"total_pages":1,"first_page":true,"last_page":true,"previous_page":null,"next_page":null,"out_of_bounds":false,"offset":0}
> Server:thin 1.3.1 codename Triple Espresso
> Set-Cookie:_widgets_session=BAh7CEkiD3Nlc3Npb25faWQGOgZFRkkiJTAzYjVlNzkwZTIyNzU4YTYwMDU0M2MwOTQ2ZWI3YWU2BjsAVEkiDWxhc3RfdXJsBjsARkkiM2h0dHA6Ly9tYWluYW5kbWUtc3RhZ2luZy5oZXJva3VhcHAuY29tL3VzZXJzLzEGOwBGSSIQX2NzcmZfdG9rZW4GOwBGSSIxdjd0SEp6cVhKamh5YTh1cnBUdmpBb0w5aVA0bS9QTEdON3g1UlFUYnBkND0GOwBG--71b3a24c216a414d8db04f312b5300c818e6bba4;
> path=/; HttpOnly Transfer-Encoding:Identity
> X-Request-Id:61b383ade49cba8b24a715a453ed6e1f X-Runtime:0.191485
> X-Ua-Compatible:IE=Edge,chrome=1

[Source -Adding Pagination to an API](

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Something in the lines of:

@posts = Post.paginate :page => params[:page]

respond_to do |format|
format.json {
render :json => {
:current_page => @posts.current_page,
:per_page => @posts.per_page,
:total_entries => @posts.total_entries,
:entries => @posts
}
}
end

Once you figure out what format you want, you can always define a `to_json` method on a WillPaginate::Collection.

will_paginate just gets the records back in a sliced manner. So it just gets an array from your database.

When you render as json, that's rails going over the array of objects and calling as_json on them.

So yes, you can will_paginate rendering out as json.