From 49d7536fa761e2ff147375ed85146feaca59ff65 Mon Sep 17 00:00:00 2001
From: Jon Birke <jonbirke0927@gmail.com>
Date: Wed, 4 Dec 2024 19:06:21 -0500
Subject: [PATCH] add previous attribute

---
 gem/lib/pagy/keyset.rb               | 19 +++++++++++++++++++
 gem/lib/pagy/keyset/active_record.rb |  3 +++
 2 files changed, 22 insertions(+)

diff --git a/gem/lib/pagy/keyset.rb b/gem/lib/pagy/keyset.rb
index d4df6d8ff..c86a1af9c 100644
--- a/gem/lib/pagy/keyset.rb
+++ b/gem/lib/pagy/keyset.rb
@@ -60,6 +60,25 @@ def next
                 end
     end
 
+    # Return the previous page
+    def previous
+      records
+
+      @previous ||= begin
+                  hash = keyset_attributes_from(@records.first)
+                  json = @vars[:jsonify_keyset_attributes]&.(hash) || hash.to_json
+                  B64.urlsafe_encode(json)
+                end
+
+      return @previous if previous?
+
+      nil
+    end
+
+    def previous?
+      filter_oldest.limit(1).exists?
+    end
+
     # Fetch the array of records for the current page
     def records
       @records ||= begin
diff --git a/gem/lib/pagy/keyset/active_record.rb b/gem/lib/pagy/keyset/active_record.rb
index 0d0155b57..813266cb8 100644
--- a/gem/lib/pagy/keyset/active_record.rb
+++ b/gem/lib/pagy/keyset/active_record.rb
@@ -20,6 +20,9 @@ def extract_keyset
       # Filter the newest records
       def filter_newest = @set.where(filter_newest_query, **@latest)
 
+      # Filter the oldest records
+      def filter_oldest = @set.reverse_order.where(filter_newest_query, **@previous)
+
       # Append the missing keyset keys if the set is restricted by select
       def apply_select
         @set.select(*@keyset.keys)