Rails File Upload

File Upload(Save file system)

<%= form_tag(&#91;action: :upload_process), multipart: true) do %>
<label>File:
  <%= file_field_tag :upfile, size: 50 %></label>
<% end %>

Handle by upload_process
controller

def upload_process
   # get file
   file = params[:upfile]
   # file base name
   name = file.original_filename
   # permit index
   perms = ['.jpg', '.jpeg', '.gif', '.png']
   # Check
   if !perms.include?(File.extname(name).downcase)
     result = 'Can upload only image'
   elif file.size > 1.megabyte
     result = 'File size should be up to 1MB'
   else
     File.open('public/docs/#{name}', 'wb') { |f| f.write(file.read) }
	 result = "Uplod #{name}"
   end
   render text: result
end

Write file(on disk) using File class

public/docs is rails directory

How to retrieve

params[:upfile] # UploadFile object

UploadFile object

methods

Save into database

class Author < ActiveRecord::Base

  validate :file_invalid?

  def data=(data)  # write data property
    self.ctype = data.content_type
	self.photo = data.read
  end
  
  private
  def file_invalid?
     ps = ['image/jpeg', 'image/gif', 'image/png']
	 errors.add(:photo, ' is not image file') if !ps.include?(self.ctype)
	 errors.add(:photo, ' is over 1MB') if self.photo.length > 1.megabyte
  end
end

controller

def updb
  @item = Item.find(params[:id])
end

def updb_process
  @item = Item.find(params[:id])
  if @item.update(params.require(:item).permit(:data))
     render text: 'Success'
  else
     render text: @item.errors.full_messages[0]
  end
end

View

<%= form_for(@item, url: {action: updb_process, id: @item }, html:{multipart: true}) do |f| %>
<%= f.label :data, 'File' %>
<%= f.file_field :data %>
<%= f.submit 'Upload' %>
<% end %>