Rubyonrails 有人可以用清晰、简单的术语向我解释 collection_select 吗

发布于01月18日

我正在浏览collection_select个Rails API文档，它们太可怕了.

标题如下:

collection_select(object, method, collection, value_method, text_method, options = {}, html_options = {})

这是他们给出的唯一示例代码:

collection_select(:post, :author_id, Author.all, :id, :name_with_initial, :prompt => true)

有人能用一个简单的关联(比如User有许多Plans，Plan属于User)解释一下我想在语法中使用什么，为什么？

Edit 1:此外，如果你解释一下它在form_helper或常规表单中是如何工作的，那就太棒了.想象一下，您正在向一位了解web开发的web开发人员解释这一点，但他对Rails来说"相对较新".你怎么解释？

推荐答案

collection_select(
    :post, # field namespace 
    :author_id, # field name
    # result of these two params will be: <select name="post[author_id]">...

    # then you should specify some collection or array of rows.
    # It can be Author.where(..).order(..) or something like that. 
    # In your example it is:
    Author.all, 

    # then you should specify methods for generating options
    :id, # this is name of method that will be called for every row, result will be set as key
    :name_with_initial, # this is name of method that will be called for every row, result will be set as value

    # as a result, every option will be generated by the following rule: 
    # <option value=#{author.id}>#{author.name_with_initial}</option>
    # 'author' is an element in the collection or array

    :prompt => true # then you can specify some params. You can find them in the docs.
)

或者，您的示例可以表示为以下代码:

<select name="post[author_id]">
    <% Author.all.each do |author| %>
        <option value="<%= author.id %>"><%= author.name_with_initial %></option>
    <% end %>
</select>

这在FormBuilder中没有记录，但在FormOptionsHelper中有记录