ActiveModel::MissingAttributeError occurs after deploying and then goes away after a while
I have a Rails 3.0.9 app that, once it is deployed, suffers from a bunch of ActiveModel::MissingAttributeErrors that crop up causing 500s. The errors occur fairly randomly, sometimes a page will load, other times it won't, but the attributes are all existing attributes in the database and should be found.
The strange part is that after a while, the errors go away. Suddenly, they stop causing an issue.
I have searched about for a solution to this, but this error mostly occurs either when someone has done Model.all(:select => 'column_x,column_y') and are calling for column_z or when they are using cache_money. I am doing neither of these things.
Can anyone help?
Answer
You probably have a query that doesn't return all the columns (i.e. uses :select) and then cache_money; or some other ActiveRecord plugin uses an after_initialize callback, which executes whenever a new ActiveRecord object is created (i.e. when fetched from the database).
In that initialize callback, something tries to access or use an attribute that wasn't included in the :select. You'd expect this to return nil for that attribute, but an ActiveRecord::MissingAttributeError is thrown instead.
You can rescue ActiveRecord::MissingAttributeError like the article suggests, or patch the plugin(s) to use has_attribute?(:attribute_name) before they try to access or modify the attribute.