allow nil for page number parameter

README.md

@@ -246,6 +246,10 @@ articles = Article.page(2).per(30).to_a
 
 # also makes request to /articles?page=2&per_page=30
 articles = Article.paginate(page: 2, per_page: 30).to_a
+
+# keep in mind that page number can be nil - in that case default number will be applied
+# also makes request to /articles?page=1&per_page=30
+articles = Article.paginate(page: nil, per_page: 30).to_a
 ```
 
 *Note: The mapping of pagination parameters is done by the `query_builder` which is [customizable](#custom-paginator).*

lib/json_api_client/query/builder.rb

@@ -47,7 +47,7 @@ def paginate(conditions = {})
       end
 
       def page(number)
-        @pagination_params[ klass.paginator.page_param ] = number
+        @pagination_params[ klass.paginator.page_param ] = number || 1
         self
       end
 

test/unit/query_builder_test.rb

@@ -38,6 +38,32 @@ def test_can_paginate
     Article.paginate(page: 3, per_page: 6).to_a
   end
 
+  def test_pagination_default_number
+    JsonApiClient::Paginating::Paginator.page_param = :number
+    stub_request(:get, "http://example.com/articles?#{{page: {number: 1}}.to_query}")
+        .to_return(headers: {content_type: "application/vnd.api+json"}, body: {
+            data: [{
+                       type: "articles",
+                       id: "1",
+                       attributes: {
+                           title: "JSON API paints my bikeshed!"
+                       }
+                   }],
+            links: {
+                self:  "http://example.com/articles?#{{page: {number: 1}}.to_query}",
+                next:  "http://example.com/articles?#{{page: {number: 2}}.to_query}",
+                prev:  nil,
+                first: "http://example.com/articles?#{{page: {number: 1}}.to_query}",
+                last:  "http://example.com/articles?#{{page: {number: 6}}.to_query}"
+            }
+        }.to_json)
+
+    articles = Article.page(nil)
+    assert_equal 1, articles.current_page
+  ensure
+    JsonApiClient::Paginating::Paginator.page_param = :page
+  end
+
   def test_can_sort_asc
     stub_request(:get, "http://example.com/articles")
       .with(query: {sort: "foo"})