PG::UndefinedTable: ERROR: relation "active_storage_blobs" does not exist

Question

Updated app Rails 5.2 to 6, the following two migrations were added by the update:

    # This migration comes from active_storage (originally 20190112182829)
    class AddServiceNameToActiveStorageBlobs < ActiveRecord::Migration[6.0]
  def up
    unless column_exists?(:active_storage_blobs, :service_name)
      add_column :active_storage_blobs, :service_name, :string

      if configured_service = ActiveStorage::Blob.service.name
        ActiveStorage::Blob.unscoped.update_all(service_name: configured_service)
      end

      change_column :active_storage_blobs, :service_name, :string, null: false
    end
  end
end

and

# This migration comes from active_storage (originally 20191206030411)
class CreateActiveStorageVariantRecords < ActiveRecord::Migration[6.0]
  def up
    create_table :active_storage_variant_records do |t|
      t.belongs_to :blob, null: false, index: false
      t.string :variation_digest, null: false

      t.index %i[ blob_id variation_digest ], name: "index_active_storage_variant_records_uniqueness", unique: true
      t.foreign_key :active_storage_blobs, column: :blob_id
    end
  end
end

trying to run the migrations gives the me error on the title. Haven't found anything online, any ideas on how to fix it?

Answer 1

The active_storage_blobs table does not exist yet. You need to first run:

rails active_storage:install

This command will add 2 migrations for 2 tables: active_storage_attachments and active_storage_blobs.

These new migrations need to be run before the migrations you have above. There is a trick for this, you can consider manually changing the timestamp in the filenames of the 2 migrations you have above to one higher than the 2 new migrations active_storage:install will create.

Once all of this is sorted, run rake db:migrate