Concat Integer & String to form a method

Question

I'm kind of doubting this is possible, but I figured I'd try and see if the community can help me come up with a solution.

In my app users can create an invoice and I'm trying to allow them to set up recurring invoices from a form so they can select a number, an interval (year, month, day) and from there I'll be able to get an interval.

Ideally it'd form something like this: 1.year.from_now

which would give me the date to send the next invoice. This is a built in rails helper that I'd like to form using information from my database

So on Invoice.create I check to see if it's a recurring invoice that will be turned into a template (Recurringinvoice) and if it is I create it:

    Recurringinvoice.create(customer_id: @customer.id, company_id: @company.id, 
invoice_number: @invoice.invoice_number, private_notes: @invoice.private_notes, 
customer_notes: @invoice.customer_notes, payment_terms: @invoice.payment_terms, 
status: "unpaid", discount: @invoice.discount, po_number: @invoice.po_number, 
interval: @invoice.interval, 
invoice_interval_number: @invoice.invoice_interval_number)

What I'd like to do: @invoice.invoice_interval_number + "." + @invoice.interval + ".from_now"

That would give me 1.year.from_now, or 2.days.from_now, etc.

Is there anyway I can make this happen? Is there a better solution I'm not thinking of?

Caillou · Accepted Answer · 2015-10-16 10:49:49Z

1

In ruby, you can use the send method to call a method by its name.

@invoice.invoice_interval_number is an Integer.
@invoice.interval contains the name of a method you want to call on your Integer.
from_now is a method you want to call on the result of the previous method.

Which gives us :

@invoice.invoice_interval_number.send(@invoice.interval).from_now

Documentation : http://ruby-doc.org/core-2.2.3/Object.html#method-i-send

answered Oct 16, 2015 at 10:49

Caillou

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2 Comments

Steve Q Over a year ago

Beautiful. It works perfectly and I never knew about that.

Caillou Over a year ago

That's part of the metaprogramming possibilities of Ruby. Which is awesome :)

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