尝试在生产中解决ActionView :: MissingTemplate（heroku）

Question

在尝试通过gmail在生产（heroku）上发送电子邮件时，我很头疼。运行heroku logs时，我得到以下信息：

2016-04-15T18:20:47.117490+00:00 app[web.1]: ClienteMailer#boas_vindas: processed outbound mail in 5.8ms
2016-04-15T18:20:47.118282+00:00 app[web.1]:    (0.7ms)  ROLLBACK
2016-04-15T18:20:47.117474+00:00 app[web.1]: 
2016-04-15T18:20:47.118705+00:00 app[web.1]: Completed 500 Internal Server Error in 31ms (ActiveRecord: 6.5ms)
2016-04-15T18:20:47.120623+00:00 app[web.1]: ActionView::MissingTemplate (Missing template layouts/mailer with {:locale=>[:"pt-BR"], :formats=>[:html], :variants=>[], :handlers=>[:erb, :builder, :raw, :ruby, :coffee, :jbuilder]}. Searched in:
2016-04-15T18:20:47.120613+00:00 app[web.1]: 
2016-04-15T18:20:47.120624+00:00 app[web.1]:   * "/app/app/views"
2016-04-15T18:20:47.120625+00:00 app[web.1]:   app/mailers/cliente_mailer.rb:6:in `block (2 levels) in boas_vindas'
2016-04-15T18:20:47.120625+00:00 app[web.1]: ):
2016-04-15T18:20:47.120627+00:00 app[web.1]:   app/models/cadastro.rb:6:in `envia_email_boasvindas'
2016-04-15T18:20:47.120626+00:00 app[web.1]:   app/mailers/cliente_mailer.rb:5:in `boas_vindas'
2016-04-15T18:20:47.120626+00:00 app[web.1]:   app/mailers/cliente_mailer.rb:6:in `block in boas_vindas'
2016-04-15T18:20:47.120627+00:00 app[web.1]:   app/controllers/cadastros_controller.rb:18:in `create'

这似乎是模板的问题，但邮件程序模板位于layouts/mailer.html.erb目录中。

以下是代码ActionMailer：

寄件人/ application_mailer.rb

class ApplicationMailer < ActionMailer::Base
      default from: "Example <example@gmail.com>"
      layout 'mailer'
    end

寄件人/ cliente_mailer.rb

class ClienteMailer < ApplicationMailer
    def boas_vindas cliente
        @cliente = cliente
        mail(:to => @cliente.email, :subject => 'Example.') do |format|
            format.html { render 'boas_vindas' }
        end
    end 
end

模型/ cadastro.rb

.
.
.
after_create :envia_email_boasvindas
def envia_email_boasvindas
    ClienteMailer.boas_vindas(self).deliver
end
.
.
.

在开发过程中一切正常。我遗失或遗忘的是什么？

Answer 1

我不知道这是否是问题，但您不需要在邮件中指定格式。就这么做：

class ClienteMailer < ApplicationMailer
    def boas_vindas cliente
        @cliente = cliente
        mail(:to => @cliente.email, :subject => 'Example.')
    end 
end

这是我通常能看到的唯一区别。