Add support for nullable vector columns

lib/pgvector.rb

@@ -9,6 +9,8 @@ module Pgvector
   autoload :PG, "pgvector/pg"
 
   def self.encode(data)
+    return nil if data.nil?
+
     if data.is_a?(Vector) || data.is_a?(HalfVector) || data.is_a?(SparseVector)
       data.to_s
     else
@@ -17,6 +19,8 @@ def self.encode(data)
   end
 
   def self.decode(string)
+    return nil if string.nil?
+
     if string[0] == "["
       Vector.from_text(string).to_a
     elsif string[0] == "{"

lib/sequel/plugins/pgvector.rb

@@ -76,8 +76,11 @@ def []=(k, v)
 
         def [](k)
           if self.class.vector_columns.key?(k.to_sym)
+            value = super
+            return nil if value.nil?
+
             # to_s needed for JRuby
-            ::Pgvector.decode(super.to_s)
+            ::Pgvector.decode(value.to_s)
           else
             super
           end

test/pgvector_test.rb

@@ -24,4 +24,12 @@ def test_decode_vector
   def test_decode_sparse_vector
     assert_equal [1, 0, 2, 0, 3, 0], Pgvector.decode("{1:1.0,3:2.0,5:3.0}/6").to_a
   end
+
+  def test_encode_nil
+    assert_nil Pgvector.encode(nil)
+  end
+
+  def test_decode_nil
+    assert_nil Pgvector.decode(nil)
+  end
 end

test/sequel_test.rb

@@ -153,6 +153,19 @@ def test_instance_sparsevec_euclidean
     assert_equal [1, Math.sqrt(3)], results.map { |r| r[:neighbor_distance] }
   end
 
+  def test_nil_embedding
+    item = Item.create(id: 4)
+    item.refresh
+    assert_nil item.embedding
+  end
+
+  def test_set_nil_embedding
+    item = Item.create(id: 4, embedding: [1, 1, 1])
+    item.update(embedding: nil)
+    item.refresh
+    assert_nil item.embedding
+  end
+
   def test_model_dataset
     create_items
     sampled_item = Item.order(Sequel.function(:random)).first