如何从Rails控制台发送电子邮件：NoMethodErrornil：NilClass的未定义方法`email'

编程问答 2022-06-13

问题描述

添加欢迎邮件后，我尝试将时事通讯发送给现有订阅者。假设我想将此欢迎电子邮件发送给退出的订户，而我只需要一次使用此功能。我正在寻找一种从Rais控制台发送此电子邮件的方法。我收到“电子邮件”的NoMethodError 消息，请花一点时间在下面查看我的代码。

# app/mailers/user_mailer.rb
class UserMailer < ApplicationMailer
  default from: '[email protected]'
  layout 'bootstrap-mailer'

  def welcome_email
    @newsletter = params[:newsletter]
    @url  = root_url
    attachments.inline['welcome.png'] = File.read(Rails.root + 'welcome.png')
    make_bootstrap_mail(
      to: @newsletter.email,subject: '??‍♀️? Welcome to My Newsletter!‍'
    )
  end

end

然后从Rails控制台中拨打welcome_email 

$ rails c
Running via Spring preloader in process 10333
Loading development environment (Rails 6.0.3.3)
>> def self.send(newsletter)
>> @newsletters = Newsletter.all
>> @newsletters.each do |newsletter|
?> UserMailer.with(newsletter: @newsletter).welcome_email.deliver_Now
>> end
>> end
=> :send
>> send(@newsletters)
  Newsletter Load (0.5ms)  SELECT "newsletters".* FROM "newsletters"
UserMailer#welcome_email: processed outbound mail in 9.6ms
Traceback (most recent call last):
        5: from (irb):10
        4: from (irb):10:in `rescue in irb_binding'
        3: from (irb):3:in `send'
        2: from (irb):4:in `block in send'
        1: from app/mailers/user_mailer.rb:11:in `welcome_email'
NoMethodError (undefined method `email' for nil:NilClass)

当我运行$ Newsletter.all时，它会返回现有电子邮件 

Newsletter.all
  Newsletter Load (0.4ms)  SELECT "newsletters".* FROM "newsletters" LIMIT $1  [["LIMIT",11]]
=> #<ActiveRecord::Relation [#<Newsletter id: 1,email: "[email protected]",created_at: "2020-09-17 21:59:23",updated_at: "2020-09-17 21:59:23">,#<Newsletter id: 15,email: "[email protected]",created_at: "2020-09-18 01:20:46",updated_at: "2020-09-18 01:20:46">,#<Newsletter id: 16,email: "[email protected]",created_at: "2020-09-18 20:51:21",updated_at: "2020-09-18 20:51:21">]>

如何将这些电子邮件正确地传递到welcom_email？ 我使用的是bootstrap-email gem，它在newsletter.save上正确发送了welcome_email。 

# app/controllers/newsletters_controller.rb
class NewslettersController < ApplicationController

    def new
        @newsletter = Newsletter.new
    end

    def create
        @newsletter = Newsletter.new(newsletter_params)
        if @newsletter.save
        UserMailer.with(newsletter: @newsletter).welcome_email.deliver_Now
            flash[:success] = "You've successfully subscribed to our newsletter. You will recive confirmation email with instractions in a few minuets."
            redirect_to root_path
        else
            redirect_to root_path,alert: "Email address already subscribed to newsletter or incorrect format."
        end
    end

    private

    def newsletter_params
        params.require(:newsletter).permit(:email)
    end

end

这是用于通过create方法发送电子邮件的开发日志 

Started POST "/newsletters" for ::1 at 2020-09-20 13:00:02 -0700
Processing by NewslettersController#create as HTML
  Parameters: {"authenticity_token"=>"bSR/L+5IQB027LeCv42DX3tw120NkLPmNHMPGqFSiOK66ct8Z2N7Yx5XbBVMmbFNgVoKKoSQCPaOoKWkC+AHvg==","newsletter"=>{"email"=>"[email protected]"},"commit"=>"Subscribe to Newsletter!"}
  [1m[35m (0.2ms)[0m  [1m[35mBEGIN[0m
  ↳ app/controllers/newsletters_controller.rb:9:in `create'
  [1m[36mNewsletter Exists? (1.0ms)[0m  [1m[34mSELECT 1 AS one FROM "newsletters" WHERE LOWER("newsletters"."email") = LOWER($1) LIMIT $2[0m  [["email","[email protected]"],["LIMIT",1]]
  ↳ app/controllers/newsletters_controller.rb:9:in `create'
  [1m[36mNewsletter Create (2.4ms)[0m  [1m[32mINSERT INTO "newsletters" ("email","created_at","updated_at") VALUES ($1,$2,$3) RETURNING "id"[0m  [["email",["created_at","2020-09-20 20:00:03.020983"],["updated_at","2020-09-20 20:00:03.020983"]]
  ↳ app/controllers/newsletters_controller.rb:9:in `create'
  [1m[35m (0.7ms)[0m  [1m[35mCOMMIT[0m
  ↳ app/controllers/newsletters_controller.rb:9:in `create'
  Rendering user_mailer/welcome_email.html.erb within layouts/bootstrap-mailer
  Rendered user_mailer/welcome_email.html.erb within layouts/bootstrap-mailer (Duration: 7.8ms | Allocations: 6866)
  Rendering user_mailer/welcome_email.text.erb
  Rendered user_mailer/welcome_email.text.erb (Duration: 0.7ms | Allocations: 128)
UserMailer#welcome_email: processed outbound mail in 531.1ms
Delivered mail [email protected] (3513.0ms)
Date: Sun,20 Sep 2020 13:00:03 -0700
From: [email protected]
To: [email protected]
Message-ID: <[email protected]>
Subject: =?UTF-8?Q?=F0=9F=99=8B=F0=9F=8F=BB=E2=80=8D=E2=99=80=EF=B8=8F=F0=9F=A6=84?=
 =?UTF-8?Q?_Welcome_to_Newsletter!=E2=80=8D?=
Mime-Version: 1.0
Content-Type: multipart/related;
 boundary="--==_mimepart_5f67b4c3d687_5ba63fd8c7a7684c67176";
 charset=UTF-8
Content-transfer-encoding: 7bit

解决方法

我在UserMailer.with(newsletter: @newsletter).welcome_email.deliver_now行中用新闻通讯替换了@newsletter，然后它起作用了。

从Rails控制台

>> def self.send(newsletter)
>> @newsletters = Newsletter.all
>> @newsletters.each do |newsletter|
?> UserMailer.with(newsletter: newsletter).welcome_email.deliver_now
>> end
>> end
>> send(@newsletters)
[1m[36mNewsletter Load (0.6ms)[0m  [1m[34mSELECT "newsletters".* FROM "newsletters"[0m
 Rendering user_mailer/welcome_email.html.erb within layouts/bootstrap-mailer
 Rendered user_mailer/welcome_email.html.erb within layouts/bootstrap-mailer (Duration: 27.2ms | Allocations: 6172)
 Rendering user_mailer/welcome_email.text.erb
 Rendered user_mailer/welcome_email.text.erb (Duration: 0.5ms | Allocations: 129)
UserMailer#welcome_email: processed outbound mail in 876.2ms
Delivered mail [email protected] (518.1ms)

# Welcome email sent to each email in Newsletter

与新闻通讯控制器中的create方法不同，控制台中的代码中没有@newsleeter，因为注释中指出了@mu太短。

Voila！现在，我们知道如何从Rails控制台手动发送数据库中所有现有电子邮件的电子邮件。

actionmailerrubyrubyrubyruby-on-rails