Rails 3：如何回答csv没有模板文件？ [英] Rails 3: How to respond_with csv without having a template file?

问题描述

我有一个对象，有一个 to_csv 方法，我想传递给 respond_with 渲染csv从我的控制器。我的代码看起来像这样：

  class Admin :: ReportsController< AdminController 
 
 respond_to：csv 
 
 def trips 
 respond_with TripReport.new 
 end 
 end 
  
 
 
 
 TripReport的实例有一个to_csv方法。
 
 
 
我收到以下错误：
  ActionView :: MissingTemplate（缺少模板管理/报告/旅行与{：formats = ：csv]，：handlers => [：erb，：builder，：rjs，：rhtml，：rxml]，：locale => [：en，：en]} 
  
 
 
 
所以看起来控制器正在寻找一个模板文件来渲染，我该如何解决？
 
 
 
我宁愿csv格式以类似于json的方式响应，所以它调用对象上的 to_csv ，只是渲染输出，是这可能吗？
解决方案
我一直在努力完全相同的问题，我可能找到了一个解决方案。 
 
 
我在阅读Renderers.add源代码时发现了一些线索：json和：xml（link是用于Rails 3.0.10代码，3.1可能已经有一些改变）：
  https://github.com/rails/rails/blob /v3.0.10/actionpack/lib/action_controller/metal/renderers.rb  
 
 
 
首先，添加一个简单的 as_csv  method to your model definition：
  class Modelname< ActiveRecord :: Base 
＃... 
 def as_csv 
属性
 end 
 end 
  
这可以是任何东西，只要确保返回一个带有键/值对的哈希。哈希比数组效果更好，因为以后你可以在CSV输出中添加一个标题行。  as_csv 的想法来自Rails的 as_json 方法，它返回一个由<$ c $ 
 
 
 
使用 as_csv 方法，将以下代码放入您的应用程序中的 config / initializers 中的文件中（命名为 csv_renderer.rb ，例如）：
  require'csv'＃将一个.to_csv方法添加到数组实例
 
类数组
别名old_to_csv to_csv #keep引用原始to_csv方法
 
 def to_csv（options = Hash.new）
＃仅当第一个元素实际上具有as_csv方法$ b时才覆盖$ b return old_to_csv（options）unless self.first.respond_to？ ：as_csv 
＃使用第一行的键作为标题列
 out = first.as_csv.keys.to_csv（options）
 self.each {| r | out<< rs.server.csv（options）} 
 out 
 end 
 end 
 
 ActionController :: Renderers.add：csv do | csv，options | 
 csv = csv.respond_to？（：to_csv）？ csv.to_csv（）：csv 
 self.content_type || = Mime :: CSV 
 self.response_body = csv 
 end 
  
最后，向您的控制器代码添加CSV支持：
  ModelnamesController< ApplicationController 
 respond_to：html，：json，：csv 
 
 def index 
 @modelnames = Modelname.all 
 respond_with（@modelnames）
 end 
 
＃... 
 
 end 
  
代码主要基于：来自Rails源代码的json和：xml行为（见上面的链接）。
 
 
 
目前， code>哈希传递给块不会传递到 to_csv 调用，因为CSV是相当挑剔的选项，它允许发送。 Rails自身添加了一些默认选项（如：template和其他一些），当将它们传递给 to_csv 时，会出现错误。 
 
 
 
希望这会有帮助！
 
。您可以通过向初始化程序添加自己首选的CSV选项来更改默认的CSV呈现行为。
I have an object that has a to_csv method and I want to pass it to respond_with to render csv from my controller.  My code looks like this:
class Admin::ReportsController < AdminController

  respond_to :csv

  def trips
    respond_with TripReport.new
  end
end
Instances of TripReport have a to_csv method.

When I make a request to that action I get the following error:
ActionView::MissingTemplate (Missing template admin/reports/trips with {:formats=>[:csv], :handlers=>[:erb, :builder, :rjs, :rhtml, :rxml], :locale=>[:en, :en]} in view paths
So it looks like the controller is looking for a template file to render.  How can I get around this?

I'd rather the csv format responded in a similar way to json, so it calls to_csv on the object and just renders the output, is this possible?
解决方案
I've been struggling with the exact same problem. I might have found a solution.

I found some clues while reading the Renderers.add source code for :json and :xml (link is for Rails 3.0.10 code, 3.1 might have some changes already):
https://github.com/rails/rails/blob/v3.0.10/actionpack/lib/action_controller/metal/renderers.rb

First, add a simple as_csv method to your model definition:
class Modelname < ActiveRecord::Base
  # ...
  def as_csv
    attributes
  end
end
This can be anything, just make sure to return a hash with key/value pairs. A Hash works better than an Array, as with keys you're able to add a header row to the CSV output later on. The idea for as_csv comes from Rails' as_json method, which return a Ruby object that is used by to_json to generate the actual JSON (text) output.

With the as_csv method in place, put the following code in a file in config/initializers inside your app (name it csv_renderer.rb, for example):
require 'csv' # adds a .to_csv method to Array instances

class Array 
  alias old_to_csv to_csv #keep reference to original to_csv method

  def to_csv(options = Hash.new)
    # override only if first element actually has as_csv method
    return old_to_csv(options) unless self.first.respond_to? :as_csv
    # use keys from first row as header columns
    out = first.as_csv.keys.to_csv(options)
    self.each { |r| out << r.as_csv.values.to_csv(options) }
    out
  end
end

ActionController::Renderers.add :csv do |csv, options|
  csv = csv.respond_to?(:to_csv) ? csv.to_csv() : csv
  self.content_type ||= Mime::CSV
  self.response_body = csv
end
And finally, add CSV support to your controller code:
class ModelnamesController < ApplicationController
  respond_to :html, :json, :csv

  def index
    @modelnames = Modelname.all
    respond_with(@modelnames)
  end

  # ...

end
The initializer code is largely based on the :json and :xml behaviour from the Rails source code (see link above).

Currently, the options hash passed to the block doesn't get passed to the to_csv call, as CSV is quite picky on which options it allows to be sent. Rails adds some default options by itself (like :template and some others), which gives you an error when passing them to to_csv. You can change the default CSV rendering behaviour by adding your own preferred CSV options to the initializer, of course.

Hope this helps!

                        
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