3
當我提交表單來更新我的模型我得到在瀏覽器這個錯誤：Rails - 活動記錄「RuntimeError：不能修改凍結字符串」以某種方式與表單生成器相關？
ActiveRecord::StatementInvalid in CoachesController#update
RuntimeError: can't modify frozen String: INSERT INTO "availabilities" ("coach_id", "created_at", "day", "hour", "updated_at") VALUES (?, ?, ?, ?, ?)
軌道控制檯這樣說：
(0.0ms) begin transaction
Binary data inserted for `string` type on column `day`
SQL (0.5ms) INSERT INTO "availabilities" ("coach_id", "created_at", "day", "hour", "updated_at") VALUES (?, ?, ?, ?, ?) [["coach_id", 14], ["created_at", Mon, 27 Feb 2012 21:59:05 UTC +00:00], ["day", "Monday"], ["hour", 20], ["updated_at", Mon, 27 Feb 2012 21:59:05 UTC +00:00]]
RuntimeError: can't modify frozen String: INSERT INTO "availabilities" ("coach_id", "created_at", "day", "hour", "updated_at") VALUES (?, ?, ?, ?, ?)
(0.1ms) rollback transaction
Completed 500 Internal Server Error in 25ms
ActiveRecord::StatementInvalid (RuntimeError: can't modify frozen String: INSERT INTO "availabilities" ("coach_id", "created_at", "day", "hour", "updated_at") VALUES (?, ?, ?, ?, ?)):
app/models/coach.rb:93:in `block (2 levels) in update_general_availability'
app/models/coach.rb:92:in `each'
app/models/coach.rb:92:in `block in update_general_availability'
app/models/coach.rb:91:in `each'
app/models/coach.rb:91:in `update_general_availability'
app/controllers/coaches_controller.rb:25:in `update'
多次實驗後，我發現如何解決這個錯誤，但不是爲什麼我首先得到它。
我有兩個模型：Coach和Availabilities，與has_many和belongs_to關聯。這是可用性表的模式：
# Table name: availabilities
# id :integer not null, primary key
# coach_id :integer
# day :string(255)
# hour :integer
它存儲在白天，一個教練是免費的一週小時的一天。
我在Coach模型中寫了兩種方法來更容易地處理教練的每週可用性。他們使用嵌套的哈希表，因此您可以查詢教練在給定時間是否空閒。 （例如：general_availability["Thursday"]["12"] #=> true）
#coach.rb
class Coach < ActiveRecord::Base
...
# Creates a hash table mapping day and hour to true if available then, false otherwise
# Form is general_availability["day"]["hr"]. Per Availability model, "0" = midnight, and
# day of the week is of the form "Monday" or "Tuesday".
def general_availability
h = Hash.new()
%w(Monday Tuesday Wednesday Thursday Friday Saturday Sunday).each { |day| h[day] = Hash.new(false) }
self.availabilities.each do |a|
h[a.day][a.hour.to_s] = true
end
return h
end
# Takes a hash table of the kind returned by general_availability and updates
# this coach's records in the Availabilities table
def update_general_availability(ga_hash_table)
self.availabilities.clear
ga_hash_table.each do |day, hrs|
hrs.each do |hr, val|
self.availabilities.create({day: day, hour: hr.to_i})
end
end
end
這是部分顯示教練的每週可用性作爲表。每天/每小時單元格是一個複選框，教練可以選中或取消選中以指示它們是否免費。
<!-- availabilities/_scheduler.html.erb -->
<h2>General Availability</h2>
Please check the times below that you would generally be available for a training session.
<table class="table" id="availabilities_table">
<tr>
<th>Time</th>
<% days_of_the_week.each do |day| %>
<th><%= day %></th>
<% end %>
</tr>
<% (6..21).each do |hr| %>
<tr>
<td><%= format_as_time hr %></td>
<% days_of_the_week.each do |day| %>
<% is_checked = @general_availability[day][hr.to_s] %>
<td class="availabilities_cell">
<%= check_box_tag "availability[#{day}][#{hr}]", true, is_checked, :class => 'availabilities_check_box' %>
</td>
<% end %>
</tr>
<% end %>
</table>
這是控制器：
# coaches_controller.rb
...
def edit
@coach = current_user.coach
@general_availability = @coach.general_availability
end
def update
@coach = Coach.find(params[:id])
@coach.update_attributes(params[:coach])
if @coach.save
@coach.update_general_availability(params[:availability])
redirect_to @coach
end
# ...
end
它是線
@coach.update_general_availability(params[:availability])
導致錯誤。
現在，這是我的問題。 爲什麼這個視圖會導致上述錯誤？
<!-- edit.html.erb version 1 -->
<h1><%= @coach.user.first_name %> </h1>
<%= form_for @coach, :html => { :multipart => true } do |f| %>
<%= f.label :profile_photo %>
<%= f.file_field :profile_photo %>
<div class="field">
<%= f.label :phone_number %>
<%= f.text_field :phone_number %>
</div>
... More Form Fields Here ...
<%= render 'availabilities/scheduler' %>
<%= f.button %>
<% end %>
雖然這種觀點不？
<!-- edit.html.erb version 2 -->
<h1><%= @coach.user.first_name %> </h1>
<%= form_for @coach, :html => { :multipart => true } do |f| %>
<%= f.label :profile_photo %>
<%= f.file_field :profile_photo %>
<div class="field">
<%= f.label :phone_number %>
<%= f.text_field :phone_number %>
</div>
... More Form Fields Here ...
<%= f.button %>
<% end %>
<%= form_for @coach, :class => "form-vertical" do |f| %>
<%= render 'availabilities/scheduler' %>
<%= submit_tag "Update Schedule" %>
<% end %>
注意，在前者部分是表單生成器形式的內部，而在第二種情況下的部分呈現爲低於其自己form_for。
，在我從我上面粘貼日誌飛出的部分是此行：
Binary data inserted for `string` type on column `day`
不出現時的形式作品（例如，在表格的版本2）。這似乎很重要，但我不知道它是什麼意思或爲什麼發生。
非常感謝！