ruby on rails_允许在Ruby on Rails上发表评论

- 日理万妓 2022-12-07 12:11 174阅读 0赞

ruby on rails

## 允许评论 **(** Allowing Comments **)** ##

![Blogging outdoors on location][]

lechatnoir/E+/Getty Images

lechatnoir / E + / Getty Images

In the previous iteration, Adding RESTful Authentication, authentication was added to your blog so only authorized users could create blog posts. This iteration will add the final (and major) feature of the blog tutorial: comments. After you're finished with this tutorial, users will be able to post anonymous comments on blog posts without logging in.

在上一个迭代(添加RESTful身份验证)中，身份验证已添加到您的博客中，因此只有授权用户才能创建博客文章。 此迭代将添加博客教程的最终(也是主要)功能：注释。 完成本教程的学习后，用户无需登录即可在博客文章中发布匿名评论。

## 脚手架评论 **(** Scaffolding the Comments **)** ##

Creating the comments database tables and controller is done much in the same way the posts database tables and controller was created--by using the scaffold generator. The scaffold generator will create RESTful controllers, map routes and create database migrations. But before you take this on, you have to think about what a comment is and what its data members will be. A comment has:

创建注释数据库表和控制器的操作与使用帖子生成器创建帖子数据库表和控制器的方法相同。 支架生成器将创建RESTful控制器，映射路线并创建数据库迁移。 但是在进行此操作之前，您必须考虑什么是注释及其注释的数据成员。 评论有：

*  **Name (required field)**: The name of the commenter as a string.
    
    **名称(必填字段)** ：评论者的名称，为字符串。
 *  **Email (optional field)**: The email of the commenter as a string.
    
    **电子邮件(可选字段)** ：评论者的电子邮件(字符串)。
 *  **Body (required field)**: The body of the comment as text.
    
    正文**(必填字段)** ：注释的正文。
 *  **post**: This associates the comment with a particular blog post. This is required for the *has\_many* and *belongs\_to* associations.
    
    **post** ：将评论与特定博客帖子相关联。 *has\_many*和*belongs\_to*关联是必需的。

Once you've decided what a comment's data members are, you can run the scaffold generator. Note that the post field is of the type "references." This is a special type that will generate an ID field to link the comments table with the posts table via a foreign key.

一旦确定了注释的数据成员是什么，就可以运行脚手架生成器。 请注意，发布字段的类型为“引用”。 这是一种特殊类型，它将生成一个ID字段，以通过外键将评论表与posts表链接起来。

>   
> exists app/models/  
> 存在应用程序/模型/  
> exists app/controllers/  
> 存在应用程序/控制器/  
> exists app/helpers/  
> 存在应用程序/助手/  
> ... snip ...  
> ...剪...

Once the controllers and migrations are generated, you can go ahead and run the migration by running the db:migrate rake task.

生成控制器和迁移后，您可以继续运行db：migrate rake任务来运行迁移。

>   
> == 20080724173258 CreateComments: migrating ========  
> == 20080724173258 CreateComments：迁移========  
> \-- create\_table(:comments)  
> \-create\_table(：comments)  
> \-> 0.0255s  
> \-> 0.0255秒  
> == 20080724173258 CreateComments: migrated (0.0305s)  
> == 20080724173258 CreateComments：已迁移(0.0305s)

## 建立模型 **(** Setting up the Model **)** ##

Once the database tables are in place, you can begin setting up the model. In the model, things like data validations--to ensure required fields are present--and relations can be defined. Two relations will be used.

数据库表到位后，就可以开始设置模型了。 在该模型中，诸如数据验证之类的东西(以确保存在必填字段)可以定义关系。 将使用两种关系。

A blog post has many comments. The has\_many relationship doesn't require any special fields in the posts table, but comments table has a post\_id to link it to the posts table. From [Rails][], you can say things like **@post.comments** to get a list of Comment objects that belong to the @post object. Comments are also *dependent* on their parent Post object. If the Post object is destroyed, all child comment objects should be destroyed as well.

博客文章有很多评论。 has\_many关系在posts表中不需要任何特殊字段，但是comments表具有一个post\_id可以将其链接到posts表。 在[Rails中][Rails] ，您可以说**@ post.comments之类的内容，**以获得属于@post对象的Comment对象的列表。 注释还*取决于*其父Post对象。 如果Post对象被销毁，所有子注释对象也应被销毁。

A comment belongs to a post object. A comment can only be associated with a single blog post. The belongs\_to relationship only requires a single post\_id field to be in the comments table. To access a comment's parent post object, you can say something like **@comment.post** in Rails.

评论属于发布对象。 评论只能与单个博客文章相关联。 Emirates\_to关系仅需要在注释表中包含一个post\_id字段。 要访问评论的父帖子对象，您可以在Rails中说**@ comment.post之类**的内容。

The following are the Post and Comment models. Several validations have been added to the comment model to ensure that users fill out the required fields. Note also the has\_many and belongs\_to relationships.

以下是发布和评论模型。 注释模型中添加了一些验证，以确保用户填写必填字段。 注意has\_many和belongs\_to关系。

>   
> class Post < ActiveRecord::Base  
> 类Post <ActiveRecord :: Base  
> has\_many :comments, :dependent => :destroy  
> has\_many：评论，：depend =>：destroy  
> end  
> 结束

>   
> class Comment < ActiveRecord::Base  
> 类Comment <ActiveRecord :: Base  
> belongs\_to :post  
> 归属地：post  
> validates\_presence\_of :name  
> validates\_presence\_of：名称  
> validates\_length\_of :name, :within => 2..20  
> validates\_length\_of：name，：within => 2..20  
> validates\_presence\_of :body  
> validates\_presence\_of：body  
> end  
> 结束

## 准备注释控制器 **(** Preparing the Comments Controller **)** ##

The comments controller will not be used in the traditional way a RESTful controller is used. Firstly, it will be accessed solely from the Post views. The comment forms and display are entirely in the show action of the Post controller. So, to start with, delete the entire *app/views/comments* directory to delete all of the comment views. They won't be needed.

评论控制器将不会以传统的方式使用RESTful控制器。 首先，将仅从“帖子”视图中访问它。 注释表单和显示完全在Post控制器的show动作中。 因此，首先，删除整个*app / views / comments*目录以删除所有评论视图。 不需要它们。

Next, you need to delete some of the actions from the Comments controller. All that's needed is the *create* and *destroy* actions. All other actions can be deleted. Since the Comments controller is now just a stub with no views, you have to change a few places in the controller where it attempts to redirect to the Comments controller. Wherever there is a redirect\_to call, change it to **redirect\_to(@comment.post)**. Below is the complete comments controller.

接下来，您需要从“注释”控制器中删除一些操作。 所有需要的就是*创建*和*销毁*操作。 可以删除所有其他动作。 由于注释控制器现在只是一个没有视图的存根，因此您必须在控制器中尝试尝试重定向到注释控制器的几个位置。 无论哪里有redirect\_to调用，请将其更改为**redirect\_to(@ comment.post)** 。 以下是完整的注释控制器。

>   
> class CommentsController < ApplicationController  
> 类CommentsController <ApplicationController  
> def create  
> def创建  
> @comment = Comment.new(params\[:comment\])  
> @comment = Comment.new(params \[：comment\])  
> if @comment.save  
> 如果@ comment.save  
> ;flash\[:notice\] = 'Comment was successfully created.'  
> ; flash \[：notice\] ='注释已成功创建。'  
> redirect\_to(@comment.post)  
> redirect\_to(@ comment.post)  
> else  
> 其他  
> flash\[:notice\] = "Error creating comment: \#\{@comment.errors\}"  
> flash \[：notice\] =“创建注释时出错：\#\{@comment.errors\}”  
> redirect\_to(@comment.post)  
> redirect\_to(@ comment.post)  
> end  
> 结束  
> end  
> 结束  
> def destroy  
> def破坏  
> @comment = Comment.find(params\[:id\])  
> @comment = Comment.find(params \[：id\])  
> @comment.destroy  
> @ comment.destroy  
> redirect\_to(@comment.post)  
> redirect\_to(@ comment.post)  
> end  
> 结束  
> end  
> 结束

## 评论表 **(** The Comments Form **)** ##

One of the final pieces to put into place is the comments form, which is actually a rather simple task. There are basically two things to do: create a new Comment object in the show action of the posts controller and display a form that submits to the create action of the Comments controller. To do so, modify the show action in the posts controller to look like the following. The added line is in bold.

最后要放置的内容之一是评论表单，这实际上是一个相当简单的任务。 基本上有两件事要做：在posts控制器的show动作中创建一个新的Comment对象，并显示一个提交到Comment控制器的create动作的表单。 为此，在posts控制器中修改show动作，如下所示。 添加的行以粗体显示。

>   
> \# GET /posts/1  
> ＃GET /帖子/ 1  
> \# GET /posts/1.xml  
> ＃GET /posts/1.xml  
> def show  
> def秀  
> @post = Post.find(params\[:id\])  
> @post = Post.find(params \[：id\]) **@comment = Comment.new( :post => @post )** **@comment = Comment.new(：post => @post)**

Displaying the comment form is the same as any other form. Place this at the bottom of the view for the show action in the posts controller.

显示评论表单与任何其他表单相同。 将其放置在posts控制器中show操作的视图底部。

## 显示评论 **(** Displaying the Comments **)** ##

The final step is to actually display the [comments][]. Care must be taken when displaying user input data as a user might try to insert HTML tags which could disrupt the page. To prevent this, the **h** method is used. This method will escape any HTML tags the user tries to input. In a further iteration, a markup language such as RedCloth or a filtering method could be applied to allow users to post certain HTML tags.

最后一步是实际显示[评论][comments] 。 显示用户输入数据时必须小心，因为用户可能会尝试插入可能会破坏页面HTML标签。 为了防止这种情况，使用了**h**方法。 此方法将转义用户尝试输入的所有HTML标记。 在进一步的迭代中，可以使用诸如RedCloth之类的标记语言或一种过滤方法来允许用户发布某些HTML标签。

Comments will be displayed with a partial, just as posts were. Create a file called *app/views/posts/\_comment.html.erb* and place the following text in it. It will display the comment and, if the user is logged in and can delete the comment, also display the Destroy link to destroy the comment.

和帖子一样，评论将显示部分内容。 创建一个名为*app / views / posts / \_comment.html.erb的文件* ，并将以下文本放入其中。 它将显示注释，如果用户登录并可以删除注释，则还将显示“销毁”链接以销毁注释。

>  *says:* *说：*  
> :confirm => 'Are you sure?',  
> ：confirm =>“您确定吗？”，  
> :method => :delete if logged\_in? %>  
> ：method =>：如果已登录，则删除？ ％>

Finally, to display all of a post's comments at once, call the comments partial with **:collection => @post.comments**. This will call the comments partial for every comment that belongs to the post. Add the following line to the show view in the posts controller.

最后，要一次显示所有帖子的评论，请使用**：collection => @ post.comments**调用部分评论。 对于属于该帖子的每个评论，这将把评论称为部分评论。 将以下行添加到posts控制器的show视图中。

> 'comment', :collection => @post.comments %>

> '评论'，：collection => @ post.comments％>

One this is done, a fully-functional comment system is implemented.

完成此操作后，将实现功能齐全的评论系统。

## 下次迭代 **(** Next Iteration **)** ##

In the next tutorial iteration, simple\_format will be replaced with a more complex formatting engine called RedCloth. RedCloth allows users to create content with easy markup such as \*bold\* for bold and \_italic\_ for italic. This will be available to both blog posters and commenters.

在下一个教程迭代中，simple\_format将被称为RedCloth的更复杂的格式化引擎替换。 RedCloth允许用户创建带有简单标记的内容，例如\* bold \*代表粗体，\_italic\_代表斜体。 博客发布者和评论者都可以使用。

> 翻译自: [https://www.thoughtco.com/rails-blog-tutorial-allowing-comments-2908216][https_www.thoughtco.com_rails-blog-tutorial-allowing-comments-2908216]

ruby on rails

[Blogging outdoors on location]: /images/20221123/f6a8037dd3c54557ba47599fcd5c2e3a.png
[Rails]: https://www.thoughtco.com/what-is-ruby-2907828
[comments]: https://www.thoughtco.com/commenting-ruby-code-2908193
[https_www.thoughtco.com_rails-blog-tutorial-allowing-comments-2908216]: https://www.thoughtco.com/rails-blog-tutorial-allowing-comments-2908216