I\'m new to Ruby and wondering why I am getting an error in this situation using the \'mail\' gem in a simple Sinatra app:
post \"/email/send\" do
@recipient
As Julik says, Mail#delivery
executes your block using #instance_exec
, which simply changes self
while running a block (you wouldn't be able to call methods #to
and #from
inside the block otherwise).
What you really can do here is to use a fact that blocks are closures. Which means that it "remembers" all the local variables around it.
recipient = params[:email]
Mail.deliver do
to recipient # 'recipient' is a local variable, not a method, not an instance variable
...
end
Again, briefly:
self
#instance_exec
changes the self
; self
and are remembered by blocks because blocks are closures.I think it's because the Mail gem uses instance_exec
under the hood. instance_exec
uses instance variables from the object it's being called on and not from the caller. What I'd do is find a method in the Mail gem that does not use instance tricks but passes an explicit configuration object to the block, and proceed from there. Spares a few gray hairs.
If you'll read through the docs for Mail further you'll find a nice alternate solution that will work. Rather than use:
Mail.deliver do
to @recipient # throws error as this is undefined
from 'server@domain.com'
subject 'testing sendmail'
body 'testing sendmail'
end
you can use Mail's new()
method, passing in parameters, and ignore the block:
Mail.new(
to: @recipient,
from: 'server@domain.com',
subject: 'testing sendmail',
body: 'testing sendmail'
).deliver!
or the alternate hash element definitions:
Mail.new(
:to => @recipient,
:from => 'server@domain.com',
:subject => 'testing sendmail',
:body => 'testing sendmail'
).deliver!
In pry, or irb you'd see:
pry(main)> Mail.new(
pry(main)* to: 'me@domain.com',
pry(main)* from: 'me@' << `hostname`.strip,
pry(main)* subject: 'test mail gem',
pry(main)* body: 'this is only a test'
pry(main)* ).deliver!
=> #<Mail::Message:59273220, Multipart: false, Headers: <Date: Fri, 28 Oct 2011 09:01:14 -0700>, <From: me@myhost.domain.com>, <To: me@domain.com>, <Message-ID: <4eaad1cab65ce_579b2e8e6c42976d@myhost.domain.com>>, <Subject: test mail gem>, <Mime-Version: 1.0>, <Content-Type: text/plain>, <Content-Transfer-Encoding: 7bit>>
The new method has several variations you can use. This is from the docs also, and might work better:
As a side note, you can also create a new email through creating a Mail::Message object directly and then passing in values via string, symbol or direct method calls. See Mail::Message for more information.
mail = Mail.new
mail.to = 'mikel@test.lindsaar.net'
mail[:from] = 'bob@test.lindsaar.net'
mail['subject'] = 'This is an email'
mail.body = 'This is the body'
followed by mail.deliver!
.
Also note, in the previous example, that there are multiple ways to access the various headers in the message envelope. It's a flexible gem that seems to be well thought out and nicely follows the Ruby way.