Allow Data{base,set}#extension to not require files if the extension …

…is already registered

This is how model plugins work, and it makes it easier for applications
to use custom extensions without messing with the load path.

CHANGELOG

@@ -1,5 +1,7 @@
 === master
 
+* Allow Data{base,set}#extension to not require files if the extension is already registered (jeremyevans) (#2246)
+
 * Do not limit imports to 40 rows at a time if using pg_auto_parameterize extension with the no_auto_parameterize method (davekaro) (#2242)
 
 === 5.86.0 (2024-11-01)

lib/sequel/database/misc.rb

@@ -246,9 +246,13 @@ def cast_type_literal(type)
     # extension does not have specific support for Database objects, an Error will be raised.
     # Returns self.
     def extension(*exts)
-      Sequel.extension(*exts)
       exts.each do |ext|
-        if pr = Sequel.synchronize{EXTENSIONS[ext]}
+        unless pr = Sequel.synchronize{EXTENSIONS[ext]}
+          Sequel.extension(ext)
+          pr = Sequel.synchronize{EXTENSIONS[ext]}
+        end
+
+        if pr
           if Sequel.synchronize{@loaded_extensions.include?(ext) ? false : (@loaded_extensions << ext)}
             pr.call(self)
           end

lib/sequel/dataset/query.rb

@@ -204,7 +204,7 @@ def exclude_having(*cond, &block)
       # If no related extension file exists or the extension does not have
       # specific support for Dataset objects, an error will be raised.
       def extension(*exts)
-        Sequel.extension(*exts)
+        exts.each{|ext| Sequel.extension(ext) unless Sequel.synchronize{EXTENSIONS[ext]}}
         mods = exts.map{|ext| Sequel.synchronize{EXTENSION_MODULES[ext]}}
         if mods.all?
           with_extend(*mods)
@@ -1359,9 +1359,13 @@ def simple_select_all?
     unless TRUE_FREEZE
       # Load the extensions into the receiver, without checking if the receiver is frozen.
       def _extension!(exts)
-        Sequel.extension(*exts)
         exts.each do |ext|
-          if pr = Sequel.synchronize{EXTENSIONS[ext]}
+          unless pr = Sequel.synchronize{EXTENSIONS[ext]}
+            Sequel.extension(ext)
+            pr = Sequel.synchronize{EXTENSIONS[ext]}
+          end
+
+          if pr
             pr.call(self)
           else
             raise(Error, "Extension #{ext} does not have specific support handling individual datasets (try: Sequel.extension #{ext.inspect})")

spec/core/database_spec.rb

@@ -3043,6 +3043,21 @@ def min_max(type, db_type, opts={})
   end
 end
 
+describe "Database extensions without files" do
+  before do
+    @db = Sequel.mock
+    @_extensions = Sequel::Database::EXTENSIONS.dup
+  end
+  after do
+    Sequel::Database::EXTENSIONS.replace(@_extensions)
+  end
+
+  it "should work if they are already registered" do
+    Sequel::Database.register_extension(:foo, Module.new{def a; 1; end})
+    @db.extension(:foo).a.must_equal 1
+  end
+end
+
 describe "Database extensions" do
   before(:all) do
     class << Sequel
@@ -3057,8 +3072,10 @@ class << Sequel
   end
   before do
     @db = Sequel.mock
+    @_extensions = Sequel::Database::EXTENSIONS.dup
   end
   after do
+    Sequel::Database::EXTENSIONS.replace(@_extensions)
     Sequel::Database.instance_variable_set(:@initialize_hook, proc{|db| })
   end
 

spec/core/dataset_spec.rb

@@ -5454,6 +5454,18 @@ def complex_expression_sql_append(sql, op, args)
   end
 end
 
+describe "Dataset extensions without files" do
+  after do
+    Sequel::Dataset::EXTENSIONS.delete(:foo)
+    Sequel::Dataset.const_get(:EXTENSION_MODULES).delete(:foo)
+  end
+
+  it "should work if they are already registered" do
+    Sequel::Dataset.register_extension(:foo, Module.new{def a; 1; end})
+    Sequel.mock.dataset.extension(:foo).a.must_equal 1
+  end
+end
+
 describe "Dataset extensions" do
   before(:all) do
     class << Sequel