From 766c5527e7a774b85df67cfd96c62d3a5339d0cd Mon Sep 17 00:00:00 2001
From: fatkodima <fatkodima123@gmail.com>
Date: Thu, 29 Aug 2024 23:23:29 +0300
Subject: [PATCH] Fix renaming columns for tables with long names

Fixes #59.
---
 CHANGELOG.md                                  |  2 ++
 lib/online_migrations/schema_statements.rb    | 31 ++++++++++++++-----
 .../renaming_columns_test.rb                  | 18 +++++++++++
 3 files changed, 44 insertions(+), 7 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2a3b317..eb149d4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,7 @@
 ## master (unreleased)
 
+- Fix renaming columns for tables with long names
+
 ## 0.19.3 (2024-08-09)
 
 - Fix idempotency for `add_index`/`remove_index` for expression indexes
diff --git a/lib/online_migrations/schema_statements.rb b/lib/online_migrations/schema_statements.rb
index 37fc2d1..06b9528 100644
--- a/lib/online_migrations/schema_statements.rb
+++ b/lib/online_migrations/schema_statements.rb
@@ -179,7 +179,7 @@ def initialize_column_rename(table_name, column_name, new_column_name)
     #
     def initialize_columns_rename(table_name, old_new_column_hash)
       transaction do
-        rename_table_create_view(table_name, old_new_column_hash)
+        __rename_table_and_create_view(table_name, old_new_column_hash)
       end
     end
 
@@ -214,7 +214,9 @@ def revert_initialize_column_rename(table_name, column_name = nil, new_column_na
     def revert_initialize_columns_rename(table_name, _old_new_column_hash = nil)
       transaction do
         execute("DROP VIEW #{quote_table_name(table_name)}")
-        rename_table("#{table_name}_column_rename", table_name)
+
+        tmp_table = __tmp_table_name_for_column_rename(table_name)
+        rename_table(tmp_table, table_name)
       end
     end
 
@@ -241,7 +243,9 @@ def finalize_column_rename(table_name, column_name, new_column_name)
     def finalize_columns_rename(table_name, old_new_column_hash)
       transaction do
         execute("DROP VIEW #{quote_table_name(table_name)}")
-        rename_table("#{table_name}_column_rename", table_name)
+
+        tmp_table = __tmp_table_name_for_column_rename(table_name)
+        rename_table(tmp_table, table_name)
         old_new_column_hash.each do |column_name, new_column_name|
           rename_column(table_name, column_name, new_column_name)
         end
@@ -273,7 +277,7 @@ def revert_finalize_columns_rename(table_name, old_new_column_hash)
         old_new_column_hash.each do |column_name, new_column_name|
           rename_column(table_name, new_column_name, column_name)
         end
-        rename_table_create_view(table_name, old_new_column_hash)
+        __rename_table_and_create_view(table_name, old_new_column_hash)
       end
     end
 
@@ -906,7 +910,8 @@ def pk_and_sequence_for(table)
       if renamed_tables.key?(table)
         super(renamed_tables[table])
       elsif renamed_columns.key?(table)
-        super("#{table}_column_rename")
+        tmp_table = __tmp_table_name_for_column_rename(table)
+        super(tmp_table)
       else
         super
       end
@@ -1046,8 +1051,9 @@ def __schema_for_table(table_name)
         schema ? quote(schema) : "current_schema()"
       end
 
-      def rename_table_create_view(table_name, old_new_column_hash)
-        tmp_table = "#{table_name}_column_rename"
+      def __rename_table_and_create_view(table_name, old_new_column_hash)
+        tmp_table = __tmp_table_name_for_column_rename(table_name)
+
         rename_table(table_name, tmp_table)
         column_mapping = old_new_column_hash.map do |column_name, new_column_name|
           "#{quote_column_name(column_name)} AS #{quote_column_name(new_column_name)}"
@@ -1059,5 +1065,16 @@ def rename_table_create_view(table_name, old_new_column_hash)
             FROM #{quote_table_name(tmp_table)}
         SQL
       end
+
+      def __tmp_table_name_for_column_rename(table_name)
+        suffix = "_column_rename"
+
+        # On ActiveRecord 7.1 can use table_name_length instead of max_identifier_length,
+        # see https://github.com/rails/rails/pull/45136.
+        # Also we need to account for "_pkey", because older versions does not correctly rename
+        # tables with long names. Remove when supporting newer versions only.
+        prefix_length = max_identifier_length - "_pkey".size - suffix.length
+        table_name[0, prefix_length] + suffix
+      end
   end
 end
diff --git a/test/schema_statements/renaming_columns_test.rb b/test/schema_statements/renaming_columns_test.rb
index 0e38ff7..b1f4639 100644
--- a/test/schema_statements/renaming_columns_test.rb
+++ b/test/schema_statements/renaming_columns_test.rb
@@ -204,6 +204,24 @@ def test_revert_finalize_columns_rename
       end
     end
 
+    def test_rename_column_in_table_with_long_name
+      # For ActiveRecord 7.1 use @connection.max_identifier_length, because older versions
+      # does not correctly generate pkey names when renaming, so need to use a shorter identifier.
+      table_name = "a" * 55
+      @connection.create_table(table_name, force: true) do |t|
+        t.string :foo
+      end
+
+      @connection.initialize_column_rename(table_name, :foo, :bar)
+      @connection.finalize_column_rename(table_name, :foo, :bar)
+
+      column_names = @connection.columns(table_name).map(&:name)
+
+      assert_equal ["id", "bar"], column_names
+    ensure
+      @connection.drop_table(table_name, if_exists: true)
+    end
+
     # Test that it is properly reset in rails tests using fixtures.
     def test_initialize_column_rename_and_resetting_sequence
       column_renames("fname" => "first_name")