tag类的Helper
form_tag
<%= form_tag("/search", method: "get") do %>
<%= label_tag(:q, "Search for:") %>
<%= text_field_tag(:q) %>
<%= submit_tag("Search") %>
<% end %>
#生成HTML如下
<form accept-charset="UTF-8" action="/search" method="get">
<label for="q">Search for:</label>
<input id="q" name="q" type="text" />
<input name="commit" type="submit" value="Search" />
</form>
#生成的表单的每个input属性都有ID属性，其值和name属性的值是一样的
form_tag({controller: "people", action: "search"}, method: "get", class: "nifty_form")
#第二个hash参数为html属性
<form accept-charset="UTF-8" action="/people/search" method="get" class="nifty_form">
复选框
<%= check_box_tag(:pet_dog, "12") %>
<input id="pet_dog" name="pet_dog" type="checkbox" value="12" />
单选框
<%= radio_button_tag(:age, "child") %>
<input id="age_child" name="age" type="radio" value="child" />
处理模型对象
#如果控制器定义了@person实例变量，有属性name ="Henry"
<%= text_field(:person, :name) %>
#生成如下
<input id="person_name" name="person[name]" type="text" value="Hery" />
#params获取的值为
{'person' => {'name' => 'Henry'}}
#可以使用params[:person][:name]获取提交的值
#如果@person实例是数据库表nurse_aid_person，那么产生的代码如下
<input id="person_name" name="nurse_aid_person[name]" type="text" value="Hery" />
Hash
#Hash可以随意嵌套
<input id="person_address_city" name="person[address][city]" type="text"
value="New York"/>
#获取的params为
{'person'=>{'address'=>{'city'=>'New York'}}}
params[:person][:address][:city]
数组
#一般情况下Rails回忽略重复的参数名
<input name="person[phone_number][]" type="text"/>
<input name="person[phone_number][]" type="text"/>
<input name="person[phone_number][]" type="text"/>
#params[:person][:phone_number]是一个数组
Hash和数组结合
<input name="addresses[][line1]" type="text"/>
<input name="addresses[][line2]" type="text"/>
<input name="addresses[][city]" type="text"/>
#params[:addresses]值是一个由Hash组成的数组
form_for表单绑定对象
<%= form_for @article, url: {action: "create"}, html: {class: "nifty_form"} do |f| %>
<%= f.text_field :title %>
<%= f.text_area :body, size: "60x12" %>
<%= f.submit "Create" %>
<% end %>
<form action="/articles/create" method="post" class="nifty_form">
<input id="article_title" name="article[title]" type="text" />
<textarea id="article_body" name="article[body]" cols="60" rows="12"></textarea>
<input name="commit" type="submit" value="Create">
</form>
fields_for方法
#同一表单中编辑多个模型对象时经常使用fields_for方法。
#eg、有个Person模型，和ContactDetail模型关联
<%= form_for @person, url: {action: "create"} do |person_form| %>
<%= person_form.text_field :name %>
<%= fields_for @person.contact_detail do |contact_details_form| %>
<%= contact_details_form.text_field :phone_number %>
<% end %>
<% end %>
#生成的HTML代码如下
<form action="/people/create" class="new_person" id="new_person" method="post">
<input id="person_name" name="person[name]" type="text" />
<input id="contact_detail_phone_number" name="contact_detail[phone_number]" type="text" />
</form>
命名空间
#admin命名空间
form_for [:admin, @article] #admin_article_path(@article)
form_for[:admin, :management, @article]
文件处理
上传文件
#params[:picture]
<%= form_tag({action: :upload}, multipart: true) do %>
<%= file_field_tag 'picture' %>
<% end %>
#params[:person][:picture]
<%= form_for @person do |f| %>
<%= f.file_field :picture %>
<% end %>
处理上传
#可以使用CarrierWave和Paperclip等第三方库
def upload
upload_io = params[:person][:picture]
File.open(Rails.root.join('public', uploads, upload_io.original_filename), 'wb') do |file|
file.write(uploaded_io.read)
end
end
使用Ajax上传文件
<%= form_for @person, builder: LabellingFormBuilder do |f| %>
<%= f.text_field :first_name %>
<% end %>
#定制表单构造器
class LabellingFormBuilder < ActionView::Helpers::FormBuilder
def text_field(attribute, options=[])
label(attribute) + super
end
end
外部资源
#如果不需要access_token的话，可以关闭，如果需要，设置authenticity_token的值
<%= form_tag 'http://www.baidu.com', authenticity_token: false do %>
...
<% end %>
复杂的表单
class Person < ActiveRecord::Base
has_many :addresses
accepts_nested_attributes_for :addresses, allow_destroy: true,
reject_if: lambda{|attributes| attributes['kind'].blank?}
#自动为Person对象创建address_attributes=方法，用于创建、更新、删除地址操作
end
class Address < ActiveRecord::Base
belongs_to :person
end
嵌套表单
<%= form_for @person do |f| %>
Addresses:
<ul>
<%= fields_for @person.addresses do |addresses_form| %>
<li>
<%= addresses_form.label :kind %>
<%= addresses_form.text_field :kind %>
<%= addresses_form.label :street %>
<%= addresses_form.text_field :street %>
</li>
<% end %>
</ul>
<% end %>
如果关联支持嵌套属性，fields_for方法会为关联中的每个元素执行一遍代码块，如果没有Address，就不执行，一般做法是在控制器中构建一个或者多个空的子属性。这样至少会有一组字段显示出来。
def new
@person = Person.new
2.times { @person.addresses.build }
end
如果用户提交了两个地址,提交的参数如下
{
'person' => {
'name' => 'John Doe',
'addresses_attributes' => {
'0' => {
'kind' => 'Home',
'street' => '221b Baker Street'
},
'1' => {
'kind' => 'Office',
'street' => '31 Spooner Street'
}
}
}
}
控制器端
def create
@person = Person.new(person_params)
end
private
def person_params
params.require(:person).permit(:name, addresses_attributes:[:id, :kind, :street])
end
删除属性
#表单
<%= form_for @person do |f| %>
Addresses:
<ul>
<%= f.fields_for :addresses do |addresses_form| %>
<li>
#如果属性组成的hash中包含_destroy键，且值为1或true，就会删除对象
<%= addresses_form.check_box :_destroy%>
<%= addresses_form.label :kind %>
<%= addresses_form.text_field :kind %>
...
</li>
<% end %>
</ul>
<% end %>
修改控制器中的参数白名单
def person_params
params.require(:person).
permit(:name, addresses_attributes: [:id, :kind, :street, :_destroy])
end
