Add multiple sort field support in sort_link

This patch allows users to sort on multiple fields with the sort_link
helper.

To specify sorting on multiple fields:

  sort_link(:kind, [:kind, 'name asc'])

This will create a sort link that sorts first by kind, and then by
name. The first `:kind` parameter ensures that the link generated
shows the sort status of the `kind` field.

When you specify a sort direction in the sort fields array, the
direction is locked to that direction. In the above example, clicking
the resulting link would toggle sorting of the kind field, but the name
field would always sort ascending.

Also added was the ability to specify multiple default_order fields
with a hash:

  sort_link(:kind, [:kind, :name],
            :default_order => { :name => 'asc', :kind => 'desc' })

Clicking the resulting link will toggle the sort directions of both
`name` and `kind`, sorting the `name` field by default ascending, and
the `kind` field descending.

lib/ransack/helpers/form_helper.rb

@@ -55,6 +55,7 @@ def search_form_for(record, options = {}, &proc)
         form_for(record, options, &proc)
       end
 
+      # sort_link @q, :name, [:name, 'kind ASC'], 'Player Name'
       def sort_link(search, attribute, *args)
         # Extract out a routing proxy for url_for scoping later
         if search.is_a?(Array)
@@ -65,39 +66,75 @@ def sort_link(search, attribute, *args)
         raise TypeError, "First argument must be a Ransack::Search!" unless
           Search === search
 
+        # This is the field that this link represents. The direction of the sort icon (up/down arrow) will
+        # depend on the sort status of this field
+        field_name = attribute.to_s
+
+        # Determine the fields we want to sort on
+        sort_fields = if Array === args.first
+          args.shift
+        else
+          Array(field_name)
+        end
+
+        label = if ! args.first.try(:is_a?, Hash)
+          args.shift.to_s
+        else
+          Translate.attribute(field_name, :context => search.context)
+        end
+
+        options = args.first.is_a?(Hash) ? args.shift.dup : {}
+        default_order = options.delete :default_order
+        # If the default order is a hash of fields, duplicate it and let us access it with strings or symbols
+        default_order = default_order.dup.with_indifferent_access if Hash === default_order
+
         search_params = params[search.context.search_key].presence ||
           {}.with_indifferent_access
 
-        attr_name = attribute.to_s
+        # Find the current direction (if there is one) of the primary sort field
+        if existing_sort = search.sorts.detect { |s| s.name == field_name }
+          field_current_dir = existing_sort.dir
+        end
 
-        name = (
-          if args.size > 0 && !args.first.is_a?(Hash)
-            args.shift.to_s
-          else
-            Translate.attribute(attr_name, :context => search.context)
+        sort_params = []
+
+        Array(sort_fields).each do |sort_field|
+          attr_name, new_dir = sort_field.to_s.downcase.split(/\s+/)
+          current_dir = nil
+
+          # if the user didn't specify the sort direction, detect the previous
+          # sort direction on this field and reverse it
+          if %w{ asc desc }.none? { |d| d == new_dir }
+            if existing_sort = search.sorts.detect { |s| s.name == attr_name }
+              current_dir = existing_sort.dir
+            end
+
+            new_dir = if current_dir
+              current_dir == desc ? asc : desc
+            else
+              if Hash === default_order
+                default_order[attr_name] || asc
+              else
+                default_order || asc
+              end
+            end
           end
-          )
 
-        if existing_sort = search.sorts.detect { |s| s.name == attr_name }
-          prev_attr, prev_dir = existing_sort.name, existing_sort.dir
+          sort_params << "#{attr_name} #{new_dir}"
         end
 
-        options = args.first.is_a?(Hash) ? args.shift.dup : {}
-        default_order = options.delete :default_order
-        current_dir = prev_attr == attr_name ? prev_dir : nil
-
-        if current_dir
-          new_dir = current_dir == desc ? asc : desc
-        else
-          new_dir = default_order || asc
+        # if there is only one sort parameter, remove it from the array and just
+        # use the string as the parameter
+        if sort_params.size == 1
+          sort_params = sort_params.first
         end
 
         html_options = args.first.is_a?(Hash) ? args.shift.dup : {}
-        css = ['sort_link', current_dir].compact.join(' ')
+        css = ['sort_link', field_current_dir].compact.join(' ')
         html_options[:class] = [css, html_options[:class]].compact.join(' ')
         query_hash = {}
         query_hash[search.context.search_key] = search_params
-        .merge(:s => "#{attr_name} #{new_dir}")
+          .merge(:s => sort_params)
         options.merge!(query_hash)
         options_for_url = params.merge options
 
@@ -108,7 +145,7 @@ def sort_link(search, attribute, *args)
         end
 
         link_to(
-          [ERB::Util.h(name), order_indicator_for(current_dir)]
+          [ERB::Util.h(label), order_indicator_for(field_current_dir)]
             .compact
             .join(non_breaking_space)
             .html_safe,

spec/ransack/helpers/form_helper_spec.rb

@@ -145,6 +145,131 @@ module Helpers
         }
       end
 
+      describe '#sort_link with multiple search_keys defined as an array' do
+        subject { @controller.view_context
+          .sort_link(
+            [:main_app, Person.search(:sorts => ['name desc', 'email asc'])],
+            :name, [:name, 'email DESC'],
+            :controller => 'people'
+          )
+        }
+        it {
+          should match(
+            if ActiveRecord::VERSION::STRING =~ /^3\.[1-2]\./
+              /people\?q%5Bs%5D%5B%5D=name\+asc&q%5Bs%5D%5B%5D=email+desc/
+            else
+              /people\?q(%5B|\[)s(%5D|\])(%5B|\[)(%5D|\])=name\+asc&q(%5B|\[)s(%5D|\])(%5B|\[)(%5D|\])=email\+desc/
+            end
+          )
+        }
+        it {
+          should match /sort_link desc/
+        }
+        it {
+          should match /Full Name ▼/
+        }
+      end
+
+      describe '#sort_link with multiple search_keys defined as an array should flip multiple fields specified without a direction' do
+        subject { @controller.view_context
+          .sort_link(
+            [:main_app, Person.search(:sorts => ['name desc', 'email asc'])],
+            :name, [:name, :email],
+            :controller => 'people'
+          )
+        }
+        it {
+          should match(
+            if ActiveRecord::VERSION::STRING =~ /^3\.[1-2]\./
+              /people\?q%5Bs%5D%5B%5D=name\+asc&q%5Bs%5D%5B%5D=email+desc/
+            else
+              /people\?q(%5B|\[)s(%5D|\])(%5B|\[)(%5D|\])=name\+asc&q(%5B|\[)s(%5D|\])(%5B|\[)(%5D|\])=email\+desc/
+            end
+          )
+        }
+        it {
+          should match /sort_link desc/
+        }
+        it {
+          should match /Full Name ▼/
+        }
+      end
+
+      describe '#sort_link with multiple search_keys defined as an array should allow a default_order to be specified' do
+        subject { @controller.view_context
+          .sort_link(
+            [:main_app, Person.search()],
+            :name, [:name, :email],
+            :controller => 'people',
+            :default_order => 'desc'
+          )
+        }
+        it {
+          should match(
+            if ActiveRecord::VERSION::STRING =~ /^3\.[1-2]\./
+              /people\?q%5Bs%5D%5B%5D=name\+desc&q%5Bs%5D%5B%5D=email+desc/
+            else
+              /people\?q(%5B|\[)s(%5D|\])(%5B|\[)(%5D|\])=name\+desc&q(%5B|\[)s(%5D|\])(%5B|\[)(%5D|\])=email\+desc/
+            end
+          )
+        }
+        it {
+          should match /sort_link/
+        }
+        it {
+          should match /Full Name/
+        }
+      end
+
+      describe '#sort_link with multiple search_keys defined as an array should allow multiple default_orders to be specified' do
+        subject { @controller.view_context
+          .sort_link(
+            [:main_app, Person.search()],
+            :name, [:name, :email],
+            :controller => 'people',
+            :default_order => { 'name' => 'desc', :email => 'asc' }
+          )
+        }
+        it {
+          should match(
+            if ActiveRecord::VERSION::STRING =~ /^3\.[1-2]\./
+              /people\?q%5Bs%5D%5B%5D=name\+desc&q%5Bs%5D%5B%5D=email+asc/
+            else
+              /people\?q(%5B|\[)s(%5D|\])(%5B|\[)(%5D|\])=name\+desc&q(%5B|\[)s(%5D|\])(%5B|\[)(%5D|\])=email\+asc/
+            end)
+        }
+        it {
+          should match /sort_link/
+        }
+        it {
+          should match /Full Name/
+        }
+      end
+
+      describe '#sort_link with multiple search_keys with multiple default_orders should not override a specified order' do
+        subject { @controller.view_context
+          .sort_link(
+            [:main_app, Person.search()],
+            :name, [:name, 'email desc'],
+            :controller => 'people',
+            :default_order => { 'name' => 'desc', :email => 'asc' }
+          )
+        }
+        it {
+          should match(
+            if ActiveRecord::VERSION::STRING =~ /^3\.[1-2]\./
+              /people\?q%5Bs%5D%5B%5D=name\+desc&q%5Bs%5D%5B%5D=email+desc/
+            else
+              /people\?q(%5B|\[)s(%5D|\])(%5B|\[)(%5D|\])=name\+desc&q(%5B|\[)s(%5D|\])(%5B|\[)(%5D|\])=email\+desc/
+            end)
+        }
+        it {
+          should match /sort_link/
+        }
+        it {
+          should match /Full Name/
+        }
+      end
       context 'view has existing parameters' do
         before do
           @controller.view_context.params.merge!({ :exist => 'existing' })