ruby-on-rails – Rails：更新嵌套属性 – nil的未定义方法`to_sym’：NilClass

概述编辑：添加了更新 *** 作,以及错误发生在哪一行 模型： class Match < ActiveRecord::Base has_and_belongs_to_many :teams has_many :match_teams has_many :teams, :through => :match_teams accepts_nested_attributes_for :match 编辑：添加了更新 *** 作,以及错误发生在哪一行

模型：

class Match < ActiveRecord::Base    has_and_belongs_to_many :teams  has_many :match_teams  has_many :teams,:through => :match_teams  accepts_nested_attributes_for :match_teams,:allow_destroy => trueend

控制器：

def new    @match = Match.new    @match_teams = 2.times do      @match.match_teams.build    end    respond_to do |format|      format.HTML # new.HTML.erb      format.Json { render Json: @match }    end  end  def update    @match = Match.find(params[:ID])    respond_to do |format|      if @match.update_attributes(params[:match])        format.HTML { redirect_to @match,notice: 'Match was successfully updated.' }        format.Json { head :ok }      else        format.HTML { render action: "edit" }        format.Json { render Json: @match.errors,status: :unprocessable_entity }      end    end  end

嵌套模型：

class MatchTeam < ActiveRecord::Base  belongs_to :match  belongs_to :teamend

协会：

class Team < ActiveRecord::Base  has_and_belongs_to_many :matchesend

视图：

<%= form_for(@match) do |f| %>  <%= f.fIElds_for :match_teams,@match_teams do |builder| %>    <%= builder.collection_select :team_ID,Team.all,:ID,:name,:include_blank => true %>  <% end %>  <% unless @match.new_record? %>    <div >      <%= f.label :winning_team_ID %><br />      <%= f.collection_select :winning_team_ID,@match.teams,:representation %>    </div>  <% end %>  <div >    <%= f.submit %>  </div><% end %>

ParaMS：

Processing by MatchesController#update as HTMLParameters: {"utf8"=>"Ô£ô","authenticity_token"=>"QIJChzkYOPZ1hxbzTZS8H3AXc7iBzkKv3Z5darmlOsQ=","match"=>{"match_teams_attributes"=>{"0"=>{"team_ID"=>"1","ID"=>""},"1"=>{"team_ID"=>"3","ID"=>""}},"winning_team_ID"=>"3"},"commit"=>"Update Match","ID"=>"2"}

创建与2个团队的新匹配工作正常,编辑视图也显示正确的值,但更新 *** 作给我这个错误.

undefined method `to_sym' for nil:NilClassapp/controllers/matches_controller.rb:65:in `block in update'line 65: if @match.update_attributes(params[:match])

解决方法 我已经明白了.我读到像MatchTeams这样的连接表不需要ID.我猜这不是做任何嵌套表单时都是如此.我重新删除我的迁移删除了ID列的排除,现在一切正常.难道我们都不喜欢这个愚蠢的错误吗？ 总结

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