在 Rails 表单中使用 textarea 助手
为什么此代码在文本区域显示错误？
<%= form_for(:ad, :url => {:action => 'create'}) do |f| %>
<%= f.text_field(:name) %>
<%= f.text_area_tag(:text, "", :size => "50x10") %>
<%= submit_tag("Submit") %>
<% end %>
Why does this code show an error in text area?
<%= form_for(:ad, :url => {:action => 'create'}) do |f| %>
<%= f.text_field(:name) %>
<%= f.text_area_tag(:text, "", :size => "50x10") %>
<%= submit_tag("Submit") %>
<% end %>
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FormHelper方法是text_area，而不是text_area_tag。使用以下任一：
或：
The
FormHelpermethod istext_area, nottext_area_tag.Use either of the following:
or:
您在第一行中创建的
f变量是对 FormBuilder 的引用。默认情况下，它引用ActionView::Helpers::FormBuilder或者您可以创建自己的。文本区域的 FormBuilder 帮助程序称为
text_area。 FormBuilder 帮助器比常规 HTML 帮助器更智能。 Rails 模型可以逻辑嵌套，并且可以编写您的表单来反映这一点； FormBuilder 助手所做的主要事情之一是跟踪每个特定字段与数据模型的关系。当您调用
f.text_area时，由于f与名为:ad的表单关联，并且该字段名为:text 它将生成一个名为ad[text]的字段。这是一个参数约定，将在服务器上自动解析为哈希：{ :ad =>; {：文本=> “value” } }而不是简单的参数列表。这是一个巨大的便利，因为如果您有一个名为Ad的模型，您只需调用Ad.create(params[:ad])即可填充所有字段正确。text_area_tag是通用助手，不会自动连接到表单。您仍然可以让它执行与FormBuilder#text_area相同的操作，但您必须手动执行。这在 FormBuilder 帮助器不打算涵盖的情况下非常有用。The
fvariable that you are creating in the first line is a reference to your FormBuilder. By default it referencesActionView::Helpers::FormBuilderor you can create your own.The FormBuilder helper for textareas is called
text_area. FormBuilder helpers are smarter than regular HTML helpers. Rails models can be nested logically, and your forms can be written to reflect this; one of the primary things FormBuilder helpers do is keep track of how each particular field relates to your data model.When you call
f.text_area, sincefis associated with a form named:adand the field is named:textit will generate a field namedad[text]. This is a parameter convention that will be automatically parsed into a Hash on the server:{ :ad => { :text => "value" } }instead of a flat list of parameters. This is a huge convenience because if you have a Model namedAd, you can simply callAd.create(params[:ad])and all the fields will be filled in correctly.text_area_tagis the generic helper that isn't connected to a form automatically. You can still make it do the same things asFormBuilder#text_area, but you have to do it manually. This can be useful in situations that a FormBuilder helper isn't intended to cover.