Question

Using a rails console I create a Model record, then retrieve using a new variable and update some fields:

var = MyModel.new
var.name = "my name"
var.save

var2 = MyModel.last
var2.name = "your name"
var2.save

now going back to the old variable var.save simply returns true and won’t overwrite the name field to its value: "my name"

Why’s that?

Answer 1

Rails Models are ‘Dirty’ by default, meaning that attribute setting functions, attribute=(), mark the attribute as changed and tell Rails to update this attribute on the next save. This info is stored on the model, NOT in the database. On var.save, Rails only updates attributes it knows to have changed. Rails does not check the database for a discrepancy if it thinks nothing has changed (this would be incredibly slow in a production environment).

You can use var.reload to reload attributes from the database into the corresponding object.

EDIT: To clarify the comments being made above, you should be using MyModel.last not MyModel.first in your test code. If you have more than one row in your database, MyModel.first will not refer to the most recently saved object, and therefore var2 and var will refer to completely different objects.