我正在尝试创建一个类似于系统的评论,用户可以在其中添加一个“结果”到“决策”中。我喜欢隐藏结果创建表单,以‘隐藏’时,有一个添加到决策。
要做到这一点,我的最佳猜测是计算决策结果的关联实例的数量,并创建一个if语句,用于在结果实例超过0时隐藏表单。
我尝试了不同的方法来完成这个任务,但我似乎无法让计数或if语句起作用。我不熟悉编码,供你参考:-)。
有人能给我一个如何解决这个问题的建议吗?
我的代码:控制器/决策控制器. My
class DecisionsController < ApplicationController
before_action :find_decision, only: [:show, :edit, :update, :destroy]
def index
# gets all rows from decision table and puts it in @decision variable
@decisions = Decision.all
end
def show
# find only the decision entry that has the id defined in params[:id]
end
# shows the form for creating a entry
def new
@decision = Decision.new
end
# creates the entry
def create
@decision = Decision.new(decision_params)
if @decision.save
redirect_to @decision
else
render 'new'
end
end
# shows the form for editing a entry
def edit
end
# updates the entry
def update
if @decision.update(decision_params)
redirect_to @decision
else
render 'edit'
end
end
def destroy
@decision.destroy
redirect_to root_path
end
private
def find_decision
# Loads the right entry.
@decision = Decision.find(params["id"])
end
def decision_params
params.require(:decision).permit(:title, :forecast, :review_date)
end
end控制器/结果控制器
class OutcomesController < ApplicationController
def create
@decision = Decision.find(params[:decision_id])
@outcome = @decision.outcomes.create(params[:outcome].permit(:actual, :strength, :weakness))
redirect_to decision_path(@decision)
end
end模型/结果
class Outcome < ActiveRecord::Base
belongs_to :decision
end模型/决定。
class Decision < ActiveRecord::Base
has_many :outcomes
end决定/show.html.erb
<h1>Decision showpage</h1>
<h2><%= @decision.title %></h2>
<p><%= @decision.created_at %></p>
<p><%= @decision.forecast %></p>
<p><%= @decision.review_date %></p>
<%= render @decision.outcomes %>
<%= link_to "Delete Decision", decision_path(@decision), method: :delete, data: { confirm: "Are you sure?" } %>
<%= render "outcomes/form" %>
<%= render "outcomes/outcome" %>结果/_form.html.erb
<%= form_for([@decision, @decision.outcomes.build]) do |f| %>
<%= f.label :actual %>:
<%= f.text_field :actual %> <br/>
<%= f.label :strength %>:
<%= f.text_area :strength %> <br/>
<%= f.label :weakness %>:
<%= f.text_area :weakness %> <br/>
<%= f.submit %>
<% end %>结果/_outcome.html.erb
<h2>outcome</h2>
<%= @decision.outcomes.first.actual %> </br>
<h3>What i found i'm good at</h3>
<%= @decision.outcomes.first.strength %> </br>
<h3>What i found i'm weak at</h3>
<%= @decision.outcomes.first.weakness %>发布于 2015-10-21 10:18:18
<h1>Decision showpage</h1>
<h2><%= @decision.title %></h2>
<p><%= @decision.created_at %></p>
<p><%= @decision.forecast %></p>
<p><%= @decision.review_date %></p>
<%= render @decision.outcomes %>
<%= link_to "Delete Decision", decision_path(@decision), method: :delete, data: { confirm: "Are you sure?" } %>
<%if @decision.outcomes.length < 1 %>
<%= render "outcomes/form" %>
<%end%>
<%= render "outcomes/outcome" %>发布于 2015-10-21 10:46:23
听起来像标准的条件逻辑:
#app/views/decisions/show.html.erb
<h1>Decision</h1>
<h2><%= @decision.title %></h2>
<% %w(created_at forecast review_date).each do |option| %>
<%= content_tag :p, @decision.send(option) %>
<% end %>
<% if @decision.outcomes.any? %>
<%= render @decision.outcomes %>
<%= render "outcomes/form" %>
<% end %>
<%= link_to "Delete Decision", decision_path(@decision), method: :delete, data: { confirm: "Are you sure?" } %>要做到这一点,我的最佳猜测是计算决策结果的关联实例的数量,然后创建一个if语句,用于在结果实例超过0时隐藏表单。
当然-这叫条件逻辑
在您的示例中,您正在寻找几种可能的方法(用于确定关联数据的大小):
Pardeep的答案) --查询数组的长度count (SQL查询)或lengthUser.all,那么您应该使用length来避免另一个db查询。count查询size,它将适应我使用.any?是因为它在这个例子中是最简洁的。
https://stackoverflow.com/questions/33256455
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