Don't Use ActiveRecord::Base.update

You shouldn't be using ActiveRecord::Base.update (the class method).

The method arguments are a record id, and the attributes to update (can also be arrays for multiple updates). Usage might look like this:

record = Model.update(params[:id], params[:model])

However, the line that comes after that typically looks like this:

record = Model.update(params[:id], params[:model])
if record.valid?
  # do stuff

One moot point is that this actually runs the validations twice. However, it's also odd to update the record and then check in a separate method call to see if the update worked. The much better API to use for this is:

record = Model.find(params[:id])
if record.update_attributes(params[:model])
  # do stuff

What if you don't care about validations? Anytime you assume a create/save/update works and do not want to check validations, you need to use a bang method, such as create!, save!, or update_attributes!. The problem is that the implementation of ActiveRecord::Base.update uses update_attributes, not update_attributes!. So if you want to update records and assume the updates do not fail due to validation, you need to use the bang method, and shouldn't be using ActiveRecord::Base.update