Reading Agile Web Development with Rails (2nd edition)
Working with InstantRails on Windows XP Professional Sevice Pack 2
I am trying to run a migration using the command
from the command prompt.
This is the error I'm getting:
You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occured while evaluating nil.
Any ideas why is this occurring and how I can solve this?
I had a similar error. In my case, the problem was that I was trying to alter an existing table by adding a foreign key reference to a table that had existing data in it. I had a previous migration that added some test data for me. Specifically, for me, the problem was that I was trying to explicitly add the constraint in MySQL. I removed the constraint and let rails handle the relationship (probably not the best idea, but I am still learning and playing) and the error went away.
There was the exact same thread on here a few days ago....
Upgrading to 1.2 should fix your problems.
Yup, I just ran into this yesterday and it was because I was not
running 1.2.1. Upgrade and you are good to go.