`dump_schema_after_migration` applies migration tasks other than db:migrate

Closes #20743.

The task `db:_dump` now only dumps the schema if
`ActiveRecord::Base.dump_schema_after_migration` is true. This has
effects:

- `db:migrate:up`
- `db:migrate:down`
- `db:forward`
- `db:rollback`

2 files changed, 19 insertions, 9 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 794bb779fa..109f6f3cd4 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,10 @@
+*   `ActiveRecord::Base.dump_schema_after_migration` applies migration tasks
+    other than `db:migrate`. (eg. `db:rollback`, `db:migrate:dup`, ...)
+
+    Fixes #20743.
+
+    *Yves Senn*
+
 *   Add alternate syntax to make `change_column_default` reversible.
 
     User can pass in `:from` and `:to` to make `change_column_default` command
diff --git a/activerecord/lib/active_record/railties/databases.rake b/activerecord/lib/active_record/railties/databases.rake
index 66fb3ae44b..85734aea90 100644
--- a/activerecord/lib/active_record/railties/databases.rake
+++ b/activerecord/lib/active_record/railties/databases.rake
@@ -42,19 +42,22 @@ db_namespace = namespace :db do
   desc "Migrate the database (options: VERSION=x, VERBOSE=false, SCOPE=blog)."
   task :migrate => [:environment, :load_config] do
     ActiveRecord::Tasks::DatabaseTasks.migrate
-    db_namespace['_dump'].invoke if ActiveRecord::Base.dump_schema_after_migration
+    db_namespace['_dump'].invoke
   end
 
+  # IMPORTANT: This task won't dump the schema if ActiveRecord::Base.dump_schema_after_migration is set to false
   task :_dump do
-    case ActiveRecord::Base.schema_format
-    when :ruby then db_namespace["schema:dump"].invoke
-    when :sql  then db_namespace["structure:dump"].invoke
-    else
-      raise "unknown schema format #{ActiveRecord::Base.schema_format}"
+    if ActiveRecord::Base.dump_schema_after_migration
+      case ActiveRecord::Base.schema_format
+      when :ruby then db_namespace["schema:dump"].invoke
+      when :sql  then db_namespace["structure:dump"].invoke
+      else
+        raise "unknown schema format #{ActiveRecord::Base.schema_format}"
+      end
+      # Allow this task to be called as many times as required. An example is the
+      # migrate:redo task, which calls other two internally that depend on this one.
+      db_namespace['_dump'].reenable
     end
-    # Allow this task to be called as many times as required. An example is the
-    # migrate:redo task, which calls other two internally that depend on this one.
-    db_namespace['_dump'].reenable
   end
 
   namespace :migrate do