ruby-on-rails - 有人可以用清晰、简单的术语向我解释 collection_select 吗？

Question

我正在浏览collection_select的Rails API文档，它们太糟糕了。

标题是这样的:

collection_select(对象、方法、集合、value_method、text_method、选项 = {}、html_options = {})

这是他们提供的唯一示例代码:

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

有人可以解释一下，使用一个简单的关联(例如User has_many Plans，并且Plan属于User)，我想在语法中使用什么以及为什么？

编辑 1: 另外，如果您能解释它在 form_helper 或常规表单中的工作原理，那就太好了。想象一下，您正在向一位了解 Web 开发但对 Rails 来说“相对较新”的 Web 开发人员解释这一点。你会如何解释？

Answer 1

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>

这没有记录在 FormBuilder 中，但记录在 FormOptionsHelper 中