嵌套屬性與軌道4個強參數

Question

class Document < ActiveRecord::Base 

    belongs_to :user 

    has_many :attachments 
    accepts_nested_attributes_for :attachments 

end 

class DocumentsController < ApplicationController 

    def new 
    @document = get_user.documents.build 
    3.times { @document.attachments.build } 
    end 

    def create 
    @document = Document.new post_params 
    end 

    def post_params 
    params.require(:document).permit(:id, :subject, :body, attachments_attributes:[:attachment]) 
    end 

end 

_form.html.slim

= f.fields_for :attachments do |builder| 
    = builder.file_field :attachment, multiple: true 

這裏的問題是：

的附件上我post_params是空的：

{"id"=>"", "to"=>"5621", "subject"=>"Hello", "body"=>"World", "attachments_attributes"=>{"0"=>{}}} 

Answer 1

看起來這是做它的方式：

def post_params 
    params.require(:document).permit(:id, :subject, :body, attachments_attributes:[:attachment => []]) 
    end 

Answer 2

它看起來您可能會在表單標記上缺少multipart: true。

Answer 3

可能

def post_params 
    params.require(:document).permit(:id, :subject, :body, 
            attachments_attributes: ['0']) 
end