Support not_null: {name: "constaint_name"} column option for naming NOT NULL constraints on PostgreSQL 18+

This allows for altering the constraint later. It also allows for
dropping the constraint by name.

Author: jeremyevans

CHANGELOG

@@ -1,5 +1,7 @@
 === master
 
+* Support not_null: {name: "constaint_name"} column option for naming NOT NULL constraints on PostgreSQL 18+ (jeremyevans)
+
 * Support :period foreign_key option for PERIOD on PostgreSQL 18+ (jeremyevans)
 
 * Support :include unique/primary_key/exclude option for INCLUDE on PostgreSQL 11+ (jeremyevans)

lib/sequel/adapters/shared/postgres.rb

@@ -1405,6 +1405,13 @@ def column_definition_add_references_sql(sql, column)
         end
       end
 
+      def column_definition_null_sql(sql, column)
+        if column[:not_null].is_a?(Hash) && (name = column[:not_null][:name])
+          sql << " CONSTRAINT #{quote_identifier(name)}"
+        end
+        super
+      end
+
       # Handle :period option
       def column_references_table_constraint_sql(constraint)
         sql = String.new

lib/sequel/database/schema_generator.rb

@@ -118,6 +118,9 @@ def check(*args, &block)
       #         that this column references.  Unnecessary if this column
       #         references the primary key of the associated table, except if you are
       #         using MySQL.
+      # :not_null :: Similar to setting <tt>null: false</tt>, but you can provide a hash value
+      #              to specify options for the NOT NULL constraint on PostgreSQL 18+:
+      #              :name :: The name of the NOT NULL constraint
       # :null :: Mark the column as allowing NULL values (if true),
       #          or not allowing NULL values (if false).  The default is to allow NULL values.
       # :on_delete :: Specify the behavior of this column when being deleted

lib/sequel/database/schema_methods.rb

@@ -592,7 +592,12 @@ def column_definition_default_sql(sql, column)
 
     # Add null/not null SQL fragment to column creation SQL.
     def column_definition_null_sql(sql, column)
-      null = column.fetch(:null, column[:allow_null])
+      null = if column[:not_null]
+        false
+      else
+        column.fetch(:null, column[:allow_null])
+      end
+
       if null.nil? && !can_add_primary_key_constraint_on_nullable_columns? && column[:primary_key]
         null = false
       end

spec/adapters/postgres_spec.rb

@@ -1316,6 +1316,14 @@ def before_create
     proc{@db[:atest].insert(Sequel.pg_range(1..1), Sequel.pg_range(9..11))}.must_raise Sequel::Postgres::ExclusionConstraintViolation
   end if DB.server_version >= 180000
 
+  it 'supports :not_null column option with hash value to name constraint' do
+    @db.create_table(:atest){Integer :a, :not_null => {name: :atest_a_nn}}
+    proc{@db[:atest].insert}.must_raise Sequel::NotNullConstraintViolation
+    @db.alter_table(:atest){drop_constraint(:atest_a_nn)}
+    @db[:atest].insert
+    @db[:atest].select_map(:a).must_equal [nil]
+  end if DB.server_version >= 180000
+
   it 'supports using PERIOD in composite foreign key constraints' do
     @db.create_table!(:atest) do
       int4range :id
@@ -1471,7 +1479,7 @@ def before_create
   end if DB.server_version >= 180000
 
   it "should support altering inheritability of NOT NULL constraints" do
-    @db.run "CREATE TABLE atest (fk INTEGER CONSTRAINT atest_nn NOT NULL)"
+    @db.create_table(:atest){Integer :fk, :not_null => {:name => :atest_nn}}
     @db.alter_table(:atest){alter_constraint(:atest_nn, :inherit=>true)}
     @db.alter_table(:atest){alter_constraint(:atest_nn, :inherit=>false)}
   end if DB.server_version >= 180000