CODEWITHSUNDEEP
ruby-on-railsactiverecordcallbackruby-on-rails-3
Aditya Sanghi
Aditya Sanghi

Reputation: 13433

Mixed Validation and Callbacks methods

When my model instance is created, it generates an "invoice_no". This invoice_no depends on the financial_year of the invoice which is derived from the invoice_date given in the form.

Now i validate the presence of invoice_date. Only after the invoice_date is valid, can I generate the financial_year and invoice_no.

Now what would be the best way to validate for the uniqueness of invoice_no?

1. validates :invoice_date, :presence => true
2. before_create :assign_financial_year # Based on a valid invoice_date
3. before_create :generate invoice_no # Based on a valid financial_year
4. validates :invoice_no, :uniqueness => {:scope => [:financial_year, :another_field], :case_sensitive => false}

I've already put a unique index in the database on this table based on all the relevant fields.

What would be the best way to mix step 2 and 3 above with validations on step 1 and 4? or Should I not bother on the uniqueness validation in rails since it's a generated number and already handled in the database? If I don't put this validation, what would be a graceful way to handle exception if raised due to uniqueness violation if ever it is generated?

I'm fairly experienced with Rails and have thought of a few ugly ways already. Just want more opinions on strategy from other experienced Rails programmers.

Upvotes: 0

Views: 394

Answers (1)

noodl
noodl

Reputation: 17408

I don't think you need to necessarily calculate the year after the validation has run. You could do it beforehand and fail gracefully if there's no invoice_date. That way, your validation will still run and you can try again later once it's present.

Upvotes: 1

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