Fix bug with generating links for urls with query parameters included

Author: Sebastian Wilgosz

Gemfile.lock

@@ -4,6 +4,7 @@ PATH
     jsom-pagination (0.1.1)
       dry-struct (~> 1.3.0)
       pagy (~> 3.8.3)
+      rack
 
 GEM
   remote: https://rubygems.org/
@@ -40,6 +41,7 @@ GEM
       dry-logic (~> 1.0, >= 1.0.2)
     ice_nine (0.11.2)
     pagy (3.8.3)
+    rack (2.2.3)
     rake (12.3.3)
     rspec (3.9.0)
       rspec-core (~> 3.9.0)

jsom-pagination.gemspec

@@ -39,6 +39,7 @@ Gem::Specification.new do |spec|
 
   spec.add_dependency 'dry-struct', '~>1.3.0'
   spec.add_dependency 'pagy', '~>3.8.3'
+  spec.add_dependency 'rack'
 
   spec.add_development_dependency 'simplecov'
   spec.add_development_dependency 'simplecov-cobertura'

lib/jsom/pagination/links.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require 'rack'
+
 module JSOM
   module Pagination
     class Links
@@ -30,12 +32,22 @@ def last
       attr_reader :page, :total_pages, :url
 
       def initialize(page:, url:, total_pages:)
-        @url = url
+        @url = parse_url(url)
         @page = page
         @total_pages = total_pages
         generate_links
       end
 
+      def parse_url(url)
+        uri = URI.parse(URI.unescape(url))
+        url_params = Rack::Utils.parse_nested_query(
+          uri.query
+        ).delete_if { |key, _value| key == 'page' }
+        uri.query = to_query(url_params)
+        uri.query = nil if uri.query.empty?
+        uri
+      end
+
       def generate_links
         if page.number > 1
           @first = generate_url(1)
@@ -50,7 +62,8 @@ def generate_links
       end
 
       def generate_url(page_number)
-        [url, url_params(page_number)].reject(&:empty?).join('?')
+        separator = url.to_s.include?('?') ? '&' : '?'
+        [url.to_s, url_params(page_number)].reject(&:empty?).join(separator)
       end
 
       def url_params(page_number)
@@ -61,12 +74,16 @@ def url_params(page_number)
         to_query(url_params)
       end
 
-      def to_query(obj, namespace = nil)
+      def to_query(obj, namespace = '')
         query = obj.collect do |key, value|
           if value.is_a?(Hash)
-            to_query(value, namespace ? "#{namespace}[#{key}]" : key)
+            to_query(value, namespace.empty? ? key : "#{namespace}[#{key}]")
           else
-            ["#{namespace}[#{key}]", value].join('=')
+            if namespace.empty?
+              [key, value].join('=')
+            else
+              ["#{namespace}[#{key}]", value].join('=')
+            end
           end
         end.compact
 

spec/jsom/pagination/links_spec.rb

@@ -136,6 +136,25 @@ module Pagination
             last: 'https://example.com/articles?page[number]=3&page[size]=2'
           )
         end
+
+        it 'works when custom query parameters are passed in the URL' do
+          url = 'https://example.com/articles?type=published&page[number]=2&page[size]=2'
+          links = described_class.new(url: url, page: page, total_pages: 3)
+
+          expect(links.self).to eq('https://example.com/articles?type=published&page[number]=2&page[size]=2')
+          expect(links.prev).to eq('https://example.com/articles?type=published&page[size]=2')
+          expect(links.first).to eq('https://example.com/articles?type=published&page[size]=2')
+          expect(links.next).to eq('https://example.com/articles?type=published&page[number]=3&page[size]=2')
+          expect(links.last).to eq('https://example.com/articles?type=published&page[number]=3&page[size]=2')
+
+          expect(links.to_h).to eq(
+            self: 'https://example.com/articles?type=published&page[number]=2&page[size]=2',
+            prev: 'https://example.com/articles?type=published&page[size]=2',
+            first: 'https://example.com/articles?type=published&page[size]=2',
+            next: 'https://example.com/articles?type=published&page[number]=3&page[size]=2',
+            last: 'https://example.com/articles?type=published&page[number]=3&page[size]=2'
+          )
+        end
       end
     end
   end