Fix: delegate structure_dump_flags and structure_load_flags to ActiveRecord

[granti]

Fix: delegate structure_dump_flags and structure_load_flags to ActiveRecord

Problem

When running rails db:prepare:with_data with structure.sql format on Rails 7.2+, the following error occurs:

NameError: undefined local variable or method 'structure_dump_flags' for module primary

          if structure_dump_flags.is_a?(Hash)
             ^^^^^^^^^^^^^^^^^^^^
Did you mean?  structure_dump_flags_for

Root Cause

DataMigrate::DatabaseTasks uses extend ActiveRecord::Tasks::DatabaseTasks to copy methods from ActiveRecord. However, structure_dump_flags and structure_load_flags are defined as mattr_accessor on the original module, which stores values on ActiveRecord::Tasks::DatabaseTasks itself.

When dump_schema is called from DataMigrate::DatabaseTasks, it internally calls structure_dump_flags_for, which tries to access structure_dump_flags - but that accessor doesn't exist on DataMigrate::DatabaseTasks.

Solution

Add delegation methods that forward calls to the original ActiveRecord::Tasks::DatabaseTasks module:

def self.structure_dump_flags
  ActiveRecord::Tasks::DatabaseTasks.structure_dump_flags
end

def self.structure_load_flags
  ActiveRecord::Tasks::DatabaseTasks.structure_load_flags
end

Testing

• Added 5 new tests for the delegation methods
• Verified all 75 tests pass on Rails 7.2, 8.0, and 8.1
• Tests cover:
  • Proper delegation to ActiveRecord::Tasks::DatabaseTasks
  • Handling nil values
  • No NameError when accessing the flags

Reproduction Steps

1. Create a Rails 7.2+ app with config.active_record.schema_format = :sql
2. Add data_migrate gem
3. Run rails db:prepare:with_data
4. Observe NameError

After this fix, the command completes successfully.

[vprigent]

Hi Granti!

Thanks a lot for fixing this.
Upon testing, I switched a test app to your branch and ran
bundle exec rails db:migrate:with_data followed by
bundle exec rails db:drop db:prepare:with_data

it looks like when a data_schema.rb file is present, the current solution explodes?

Parse error near line 1: near "DataMigrate": syntax error
  DataMigrate::Data.define(version: 2025_10_27_185053)
  ^--- error here
bin/rails aborted!

Just wanted to report it, seems its limited to the codepath when using
config.active_record.schema_format = :sql

I'm pretty sure it would still be broken without your patch.

[houndci-bot]

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.rubocop.yml: Lint/BlockAlignment has the wrong namespace - should be Layout

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Warning: unrecognized cop Lint/LiteralInCondition found in .rubocop.yml
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[granti]

Hi Vincent,

Thank you for testing this against your test bed, and for the clear repro. That was very helpful.

You were right: the parse error is a separate bug from the structure_dump_flags NameError. prepare_all_with_data was calling load_schema with ActiveRecord’s schema_format, but DataMigrate::DatabaseTasks#schema_dump_path always points at data_schema.rb. With config.active_record.schema_format = :sql, that meant Ruby was being passed to structure_load. The same mix-up also affected the dump path after migrate.

I have pushed a follow-up commit that keeps the two schemas separate, in line with db:structure:load:with_data / db:schema:load:with_data:

• load/dump the ActiveRecord schema through ActiveRecord::Tasks::DatabaseTasks (so :sql uses structure.sql)
• always load data_schema.rb as :ruby
• keep the original structure_dump_flags / structure_load_flags delegation

If you have a moment to re-run db:migrate:with_data followed by db:drop db:prepare:with_data on your test bed, I would be grateful for a second look. Happy to adjust further if anything still looks off.

Thanks again,
Ian

[houndci-bot]

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