[Rails]form_for action to where

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參考文章:
Ruby on Rails Guides
Ruby on Rails 5.2.0
form_for but to post to a different action(stackoverflow)

如何看結果

直接以Ruby on Rails Guides為例子

form.html.erb
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<%= form_for @person, url: {action: "create"} do |person_form| %>
  <%= person_form.text_field :name %>
  <%= fields_for @person.contact_detail do |contact_detail_form| %>
    <%= contact_detail_form.text_field :phone_number %>
  <% end %>
<% end %>

開啟遊覽器按檢查可以直接看到form_for render出的form tag長得如何

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<form class="new_person" id="new_person" action="/people" accept-charset="UTF-8" method="post">
  <input name="utf8" type="hidden" value="&#x2713;" />
  <input type="hidden" name="authenticity_token" value="bL13x72pldyDD8bgtkjKQakJCpd4A8JdXGbfksxBDHdf1uC0kCMqe2tvVdUYfidJt0fj3ihC4NxiVHv8GVYxJA==" />
  <input type="text" name="person[name]" id="person_name" />
  <input type="text" name="contact_detail[phone_number]" id="contact_detail_phone_number" />
</form>

再來我們就專注於form這個tag就好！

原理

如剛剛的例子:
1.form_for會先去查看instance是什麼
2.預設去找尋對應的model存不存在
3.如存在會去找對應名稱的controller
4.when new action create, when edit action update

所以此例子會有model/persons.rb和person_controller.rb，且controller應該至少如下:

person_controller.rb
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def new
    @person = Person.new
end

def create
    @person = Person.find(params[:id])
    @person = Person.new(person_params)
    @person.save
end

private

def person_params
    params.require(:person).permit(:參數)
end

自定義

在form_for裡面可以設定
url:
controller-指定controller
action-指定用controller裡的哪個method
params-傳遞什麼params

method:指定用什麼動作(get, post…等)

例如:

form_html.erb
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<%= simple_form_for @person, url: {:controller => 'my_controller', :action => 'my_action'}, method: 'post' do |f| %>

更多實際例子可以參考這篇form_for but to post to a different action(stackoverflow)