嵌套form_for的Rails路由错误 [英] Rails Routing Error for nested form_for

问题描述

我现在已经被问了一千遍了，但这对我没有帮助。:)我去过一个小时。我的表单：

I now this has been asked a thousand times but that doesn't help me heh :) I've been at this an hour. My form:

= form_for @comment, :url_for => { :action => "create", :controller => "comments"}, :method => :post

我的耙路：

                   POST   /t/:trunk_id/r/:root_id/comments(.:format)          {:action=>"create", :controller=>"comments"}
trunk_root_comment GET    /t/:trunk_id/r/:root_id/comments/:id(.:format)      {:action=>"show", :controller=>"comments"}

错误：

undefined method `comments_path' for #<#<Class:0x007fed2c713128>:0x007fed2c71cc78>

如果我将表格命名为：

= form_for [:trunk_root, @comment], :url_for => { :action => "create", :controller => "comments"}, :method => :post do |f|

这应该使路线trunk_root_comments_path ..根据耙路正确。

which should make the route trunk_root_comments_path.. which is correct according to the rake routes.. I get:

No route matches {:controller=>"comments", :format=>nil}

非常感谢帮助。.几个小时都在看这个。.

Help is very much appreciated.. been looking at this for hours..

更新：

谢谢瑞安这么好的回答！对于我当时只是在扔东西的事情，有一个非常明确的解释，至少我现在了解得更多。实际上，我的耙路中已经有 trunk_root_comments_path可用，并且我尝试了您提到的几种组合，但我并没有真正感到震惊，因此您提供了帮助。我正在使用Mongo，但实际上没有Trunk模型，我只有一个名为@ root.trunk的根属性，尽管我有一个Trunk控制器，因此它是我的路由的一部分（可能是个不好的主意idk） 。

Thank you Ryan for such a great answer! A very clear explanation of something I was just sort of 'throwing things' at, now at least I understand better. I actually already had 'trunk_root_comments_path' available in my rake routes, and I had tried a couple of the combinations you mentioned, but I wasn't really grocking what I was missing, so you helped. I'm using Mongo and I don't actually have a Trunk model, I just have an attribute on roots called @root.trunk, though I have a trunk controller and therefore its a part of my routes(maybe a bad idea idk).

所以我尝试了您的TLDR并显示错误：

So I tried your TLDR and it said error:

Undefined method 'root_comments_path'

..原因不存在Trunk模型，我想是？..所以我将@ trunk等于正确的ID，与

.. cause no Trunk model exists, I assume?.. so I made @trunk just equal the correct id with

= form_for [@trunk, @root, @comment] do |f| 

<--我得到了'undefined method`politics_root_comments_path'..我很清楚..可能是有道理的..因为我失败了，所以我还必须尝试最明确的版本：

<- and I got 'undefined method `politics_root_comments_path''.. I figured well.. that probably makes sense.. since I'm failing I must as well try your most explicit version:

= form_for @comment, :url => (trunk_root_comments_path(:trunk_id => @root.trunk, :root_id => @root.id)) do |f| 

肯定能奏效...所以我不太确定该怎么做这对我来说奇怪的是，我在路线中具有相同深度的嵌套资源照片，并且我能够使用= form_for [：trunk_root，@photo]，：html => {：class =>'root_form'}做| f | ..但出于某种原因我不能..无论如何，我会说您给了我足够的知识以理解100％，但我认为我从20％的理解变成了50 ％的理解..我现在知道ID对路由很重要，命名的助手需要访问它们。我对url_helper的工作方式进行了介绍，但是我需要进一步阅读以真正完善它。现在，我也能够以更长的形式构造适当的路线，至少可以度过这种棘手的情况。因此，谢谢您：）

and sure enough that worked... so I'm not quite sure how to do it shorter then this.. the odd thing for me is I have another nested resource "photos" at the same level of depth in the routes and I was able to get that to work with = form_for [:trunk_root, @photo], :html => { :class => 'root_form' } do |f|.. but here for some reason I couldn't.. anyways I'd say you gave me enough to understand 100% but I think I went from 20% understanding to 50% understanding.. I know now that id's ARE important to routes, and the named helpers need access to them. I got an introduction to how the url_helper works, but would need to read more on it to really grock it fully I think. I'm also now able to construct proper routes in their longer form at least to get through tricky situations like this. So thank you :)

推荐答案

TL; DR您需要同时指定：trunk_id 和您URL中的 root_id 或使用 form_for 这样：

TL;DR You need to specify both a :trunk_id and a root_id in your URL or use form_for like this:

<%= form_for [@trunk, @root, @comment] do |f| %>

Rails试图从您提供的哈希值中构建URL，但该哈希值不会t匹配其路由表中的任何内容。您可以这样做：

Rails is attempting to build a URL from the hash you're giving it, but that hash doesn't match anything in its routing table. You could do this:

{ :controller => "comments", :action => "create", :trunk_id => trunk.id, :root_id => root.id }

但这确实有点 tl; dr 。

更酷的方法是：

trunk_root_comments_path(trunk, root)

其中 trunk 和 root 分别是 Trunk 和 Root 实例。

现在，如果您想成为超级邪恶的酷，请像这样：

Now, if you want to be super-wicked-cool, do it like this:

<%= form_for [trunk, root, comment] do |f| %>

科学！

所以这是如何运作的？小学，亲爱的：

Rails首先认识到我们正在使用 form_for 使用数组， 我们的意思是生意。 Rails使用传入的此数组并从中构建URL。它通过使用路由定义的路由帮助器来完成此任务。不幸的是，您已经以一种有趣的方式定义了您的路线，但效果并不理想，但是不要害怕！我们可以解决这个问题。

Rails first recognises that we're using form_for using an Array and that we mean business. Rails uses this array passed in and builds a URL out of it. It does this by using the routing helpers that are defined by the routes. Unfortunately, you've defined your routes in a funny way that don't play nice with this, but don't fear! We can fix this.

您可以在 config / routes.rb 中找到它：

post '/t/:trunk_id/r/:root_id/comments'

而不是这样：

post '/t/:trunk_id/r/:root_id/comments', :as => "trunk_root_comments"

您可能已经 已经拥有了：

You may alternatively already have this:

match '/t/:trunk_id/r/:root_id/comments', :via => :post

应该成为哪个：

match '/t/:trunk_id/r/:root_id/comments', :via => :post, :as => "trunk_root_comments"

无论哪种方式，您现在都不是一个，而是路线定义的两个（!!） 路径助手。它们分别是 trunk_root_comments_path 和 trunk_root_comments_url 。 这些方法的名称对于我将要向您解释的内容非常重要。请注意！

Either way, you've now got not one, but two(!!) path helpers defined by the routes. These aretrunk_root_comments_path and trunk_root_comments_url respectively. The names of these methods are super important for what I am about to explain to you. Pay attention!

所以，回到我们的 form_for 小呼叫：

So, back to our little form_for call:

<%= form_for [trunk, root, comment] do |f| %>

Rails知道我们正在使用数组，因为它可以看到它。这个数组的作用可能像魔术一样似乎，但并非如此。

Rails knows that we're using an Array because it can see it. What it does with this Array may seem like magic, but isn't really.

Rails将获取此数组的每个元素，并从不同部分构建一个路由辅助方法 name 。这实际上不是 form_for 的一部分，但可以单独使用另一种称为 url_for 的方法：

Rails will take each element of this array and build a routing helper method name up from the different parts. This isn't actually part of form_for, but another method called url_for that you can use by itself:

 url_for([trunk, root, comment])

开头，由 url_for 生成的此路由帮助器方法名称只是一个空数组（ [] ）。没什么特别的。

In the beginning, this routing helper method name generated by url_for is simply an empty array ([]). Nothing special at all.

但是然后发生的事情是特殊的！

第一个元素将是 Trunk 类的持久化实例。 持久是指将直接映射到数据库中的记录的对象。是的ORM！

The first element is going to be a persisted instance of the Trunk class. By "persisted" I mean that it's an object that maps directly to a record in the database. Yay ORMs!

Rails会知道这一点，因此会将路由助手转换为： [：trunk]

Rails will know this, and so will turn the routing helper into this: [:trunk].

第二个元素将是 Root 类的持久化实例 。 Rails也知道这一点（该死，Rails是 smart ！），然后将其附加到数组中，将其转换为 [：trunk，：root] 。

The second element is going to be a persisted instance of the Root class. Rails also knows this (damn, Rails is smart!) and will then append this to the array, turning it into [:trunk, :root]. Awesome.

Rails然后检查第三个（也是最后一个）元素。它会发现（在这种情况下）它是一个非持久性元素，即尚未保存到数据库中。 Rails对此进行了不同的处理，而是将 [：comments] 追加到数组，并将其转换为：

The third (and final) element is then checked by Rails. It sees that (in this case) it's a non-persisted element, i.e. it's not been saved to the database.. yet. Rails treats this differently and will instead append [:comments] to the array, turning it into this:

[:trunk, :root, :comments]

看看我在哪里

现在，Rails已经完成了它的工作（或者， thang ，如果您愿意的话），它将加入这三个部分像这样： trunk_root_comments ，并且为了很好的衡量，它会在其末尾放置 _path 并将其翻转进入最终的 trunk_root_comments_path 助手。

Now that Rails has done it's thing (or thang, if you like) it will join these three parts together like this: trunk_root_comments, and just for good measure it'll put _path on the end of it, turning it into the final trunk_root_comments_path helper.

然后！伙计，然后... Rails调用此方法并传递参数！就像这样：

And then! Man, and then... Rails calls this method and passes it arguments! Just like this:

trunk_root_comments_path(:trunk_id => trunk.id, :root_id => root_id)

这将生成资源的完整路径，如下所示：

This generates a full path to the resource like this:

/t/:trunk_id/r/:root_id/comments

bam！整圈！这就是Rails知道如何生成URL的方式，您不必再使用丑陋的哈希值。

And bam! Full circle! That's how Rails will know to generate the URL and you don't have to use ugly hashes anymore.

成功！

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