I have following two migrations:
One, Add column contextual_page_number to transcripts table:
class AddContextualPageNumberToTranscripts < ActiveRecord::Migration[5.2]
def change
add_column :transcripts, :contextual_page_number, :integer, default: 1
end
end
Second, changing the value of the previous added column contextual_page_number based on value of another column:
class ChangePageOffsetAndContextualPageNumberOfTranscripts < ActiveRecord::Migration[5.2]
def up
Firm.all.find_in_batches do |group|
group.each do |firm|
Apartment::Tenant.switch(firm.tenant) do
Transcript.where.not(page_offset: 0).each do |transcript|
transcript.update(
contextual_page_number: ((transcript.page_offset - 1) * -1),
page_offset: 1
)
end
end
end
end
end
def down
..
end
end
After running the migration, I am getting unknown attribute contextual_page_number error.
== 20211108132509 AddContextualPageNumberToTranscripts: migrating ============= -- add_column(:transcripts, :contextual_page_number, :integer, {:default=>1}) -> 0.0095s == 20211108132509 AddContextualPageNumberToTranscripts: migrated (0.0096s) ====
== 20220113095658 ChangePageOffsetAndContextualPageNumberOfTranscripts: migrating rails aborted! StandardError: An error has occurred, this and all later migrations canceled:
unknown attribute 'contextual_page_number' for Transcript.
I have even tried reset_column_information, but no luck:
Apartment::Tenant.switch(firm.tenant) do
Transcript.connection.schema_cache.clear!
Transcript.reset_column_information
..
end
Any clue would be of great help, thanks.
As mentioned in one of the answer, I tried reset_column_information just right after the add_column, but that didn't worked. Finally, SQL to the rescue..
sql_cmd = "UPDATE transcripts
SET contextual_page_number = ((page_offset - 1) * -1),
page_offset = 1
WHERE page_offset != 0"
Transcript.connection.execute(sql_cmd)
You need two migration files.
First, try running the migration and check schema.rb for the table transcripts and verify that the newly added column contextual_page_number is being added or not.
Once you are sure that your new column is added, then again create a new migration like, eg: MigrateTransriptsCloningsData, and then add the desired changes in the up block, then execute db:migrate to update the required changes.
My choice would be To add a new rake task and executing it. like bundle exec rake migrate_transcripts_data:start instead of keeping that logic in the db/migrate/your_new_migration_file, choice is yours.
reset_column_information should be the correct way to resolve this sort of problem if you want to use models in a migration. This isn't without its problems though.
I suspect the issue is that you are calling it too late somehow. Put it first thing in the up method of the second migration or after the add_column in the first migration.