使用强参数时如何从 fields_for 提交中获取单个属性的值？ Rails 4

Question

如果问题的标题可能有点令人困惑，我深表歉意，但我真的很难用更好的词来表达它。

我正在尝试访问 fields_for 提交中的单个属性在控制器中。

我的表单如下所示：

= form_for @match, :url => matches_search_path, remote: true do |f|
      = f.select :sport_id, options_from_collection_for_select(Sport.all, "id", "name"), {:prompt => "Select Sport..."}, class: "form-control"
      = f.fields_for @match.build_location do |g|
        = g.text_field :zip, :class => "form-control", :value => @user.location.zip, :placeholder => "Zip"
      = f.text_field :max_players, :class => "form-control", :placeholder => "Player Limit (in total)"
      = f.submit "Search", :class => "btn btn-info"

MatchesController 是这样的：

class MatchesController < ApplicationController
before_filter :current_user

def index
    @match = Match.new
    @user = current_user
end

def new
    @match = Match.new
    @match.build_location
end

def create
    @user = User.find(session[:user_id])
    @match = @user.matches.build(match_params)

    if @match.save
        redirect_to :root, :notice => "Match created."
    else
        render :new, :alert => "Failed to create match."
    end
end

def search
    # Get all matches for the searched sport
    @results = Match.sport_id(match_params[:sport_id])

    #This is where the problem is:
    @coordinates = Geocoder.coordinates(match_params[:location][:zip])

    @results = @results.select {|result| result.location.distance_from(@coordinates)}

    respond_to :js
end

private def match_params
    params.require(:match).permit(:sport_id, :name, :description, :choose_teams, :keeping_score, :max_players, :time, location_attributes: [:address, :city, :state, :zip])
end
end

路线没问题：

# Matches
resources :matches
post 'matches/search', as: :matches_search

表单提交对MatchesController中的search方法的ajax调用就好了。问题是我得到：

undefined method `[]' for nil:NilClass

行

@coordinates = Geocoder.coordinates(match_params[:location][:zip])

我尝试用谷歌搜索这个问题，但我发现最接近这个问题的是 here，在尝试访问 "hash within a hash" 时使用：

params[:outer_hash][:inner_hash]

当我使用 params[:location][:zip], match_params[:location][:zip] 或 match_params[:location_attributes][:zip] 时不起作用。

我已确认 表单中的信息已被 发送至控制器。我似乎无法正确访问它。

我到底做错了什么？

编辑：

这是表单的回复：（我屏蔽了authenticity_token）

{"utf8"=>"✓", "authenticity_token"=>"XXXXXXXXXXXXXXXXXXXXXXX", 
"match"=>{"sport_id"=>"4", 
"location"=>{"zip"=>"11211"},
"max_players"=>""},
"commit"=>"Search"}

Answer 1

我认为正在发生的事情是您的 match_params 没有让 location 参数（我猜匹配 has_one 位置）。更改行：

@coordinates = Geocoder.coordinates(match_params[:location][:zip])

至：

@coordinates = Geocoder.coordinates(params[:match][:location][:zip])

或者更好的是，将您的 match_params 更改为：

params.require(:match).permit(:sport_id, :name, :description, :choose_teams, :keeping_score, :max_players, :time, location: [:address, :city, :state, :zip])

使用强参数时如何从 fields_for 提交中获取单个属性的值？ Rails 4

How to get value of a single attribute from a fields_for submission when using strong parameters? Rails 4

ruby

forms

ruby-on-rails

fields-for