显示 ERB 语法错误的堆栈跟踪。是应用程序代码或 ERB 库的问题？

Question

我正在学习 Lynda.com 课程 Ruby Essential Training Part 3: Files, Formats, Templates 中的 ERB 章节，并且不断收到似乎是 ERB 本身的语法错误。当我输入此代码时：

#!/usr/bin/env ruby

#### Mail Merge ####
#
# Launch this Ruby file from the command line
# to get started
#

require 'erb'
require 'csv'

APP_ROOT = File.expand_path(File.dirname(__FILE__))

# files in current dir
template_path = File.join(APP_ROOT, 'letter_template.txt')
csv_path = File.join(APP_ROOT, 'us_presidents.csv')

template = File.read(template_path)

i = 0
CSV.foreach(csv_path) do |row|
  next if row[0].start_with?('Number') # Header row
  i += 1

  @last_name = row[1]
  @first_name = row[2]
  state = row[6]
  end_date = row[4] || Time.now.year

  @title = "The History of #{state}"
  @due_date = end_date
  years = Time.now.year - @due_date.to_i
  @fee = "$#{years * 365}.00"

  letter = ERB.new(template).result(binding)

  num = i < 10 ? "0#{i}" : i
  filename = "letter_#{num}.txt"
  filepath = File.join('letters', filename)

  puts "-------"
  puts filepath
  puts letter

  File.write(filepath, letter)

end

我收到此错误消息：

Traceback (most recent call last):
    15: from init.rb:20:in `<main>'
    14: from /Users/andrekibbe/.rvm/rubies/ruby-2.7.0/lib/ruby/2.7.0/csv.rb:510:in `foreach'
    13: from /Users/andrekibbe/.rvm/rubies/ruby-2.7.0/lib/ruby/2.7.0/csv.rb:658:in `open'
    12: from /Users/andrekibbe/.rvm/rubies/ruby-2.7.0/lib/ruby/2.7.0/csv.rb:511:in `block in foreach'
    11: from /Users/andrekibbe/.rvm/rubies/ruby-2.7.0/lib/ruby/2.7.0/csv.rb:1280:in `each'
    10: from /Users/andrekibbe/.rvm/rubies/ruby-2.7.0/lib/ruby/2.7.0/csv.rb:1280:in `each'
     9: from /Users/andrekibbe/.rvm/rubies/ruby-2.7.0/lib/ruby/2.7.0/csv/parser.rb:336:in `parse'
     8: from /Users/andrekibbe/.rvm/rubies/ruby-2.7.0/lib/ruby/2.7.0/csv/parser.rb:823:in `parse_quotable_loose'
     7: from /Users/andrekibbe/.rvm/rubies/ruby-2.7.0/lib/ruby/2.7.0/csv/parser.rb:49:in `each_line'
     6: from /Users/andrekibbe/.rvm/rubies/ruby-2.7.0/lib/ruby/2.7.0/csv/parser.rb:49:in `each_line'
     5: from /Users/andrekibbe/.rvm/rubies/ruby-2.7.0/lib/ruby/2.7.0/csv/parser.rb:52:in `block in each_line'
     4: from /Users/andrekibbe/.rvm/rubies/ruby-2.7.0/lib/ruby/2.7.0/csv/parser.rb:871:in `block in parse_quotable_loose'
     3: from /Users/andrekibbe/.rvm/rubies/ruby-2.7.0/lib/ruby/2.7.0/csv/parser.rb:1122:in `emit_row'
     2: from init.rb:34:in `block in <main>'
     1: from /Users/andrekibbe/.rvm/rubies/ruby-2.7.0/lib/ruby/2.7.0/erb.rb:905:in `result'
/Users/andrekibbe/.rvm/rubies/ruby-2.7.0/lib/ruby/2.7.0/erb.rb:905:in `eval': (erb):6: syntax error, unexpected '=', expecting end-of-input (SyntaxError)
;  = @due_date ; _erbout.<< "\n\n...**

堆栈跟踪中的所有内容都引用了 CSV 和 ERB 行，所以我看不到任何可以在我这边更正的内容。我错过了什么吗？

更新： letter_template.rb 添加：

Dear <%= @first_name %> <%= @last_name %>,

The following library book is overdue.

"<%= @title %>"
Due: <% = @due_date %>

Overdue fee: <%= @fee %>

Thank you for your prompt attention to this matter.

Answer 1

堆栈跟踪显示来自 ERb 的行，因为 ERb 代码是正在执行的代码。

虽然理论上问题可能出在 ERb 本身或您的模板中，但鉴于 ERb 被成千上万的开发人员使用，更有可能问题出在您的模板中和每日申请。

显示 ERB 语法错误的堆栈跟踪。是应用程序代码或 ERB 库的问题？

Stack trace showing ERB syntax error. Is the problem with app code or ERB library?

ruby

erb