Question

Seems pretty simple, but then nothing is.

I have two values:

t.integer  "quantity"
t.decimal  "unit_price",         :precision => 7, :scale => 2

I want to multiply quantity by unit_price in an each (invoice) loop:

invoice.quantity * invoice.unit_price

This causes the following error:

undefined method `*' for nil:NilClass

Do I have to convert the values first or is there something trivial I’m missing?

Thanks

Answer 1

invoice.quantity

Is returning nil.

You can tell by the error message

undefined method `*' for nil:NilClass

You are trying to execute the method * on an instance of NilClass

Check this out as an example

> nil * 5
=> undefined method `*' for nil:NilClass (NoMethodError)