# Rails 增加上傳圖片功能

###### tags: `rails`, `ruby`
環境:
> ruby 2.6.7
>
> Rails 6.1.3.1
>
> Ubuntu 20.04 LTS
>

<font color="red">**資源連結**：</font><font size=4>[**Active Storage**](https://railsguides.jp/active_storage_overview.html)</font>
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## :memo:

### Step 1: 移至ubuntu, 生成相關migration

# Ubuntu
$ rails active_storage:install
$ rails db:migrate

### Step 2: 移至需要使用圖片的models加上<font color="red">`has_one_attached :(自訂名)`</font>

# 路徑:/appname/app/models/user.rb

class User < ApplicationRecord
  has_one_attached :avatar
end

- **移至html.erb增加上傳圖片欄位**

# edit.html.erb

<%= form.file_field :avatar %>

- **移至controller.rb**

# users_controller.rb

def create
  @user.create(...., avatar: params[:avatar])
end

# show.html.erb

<% if @user.avatar.attached? %>
  <%= image_tag @user.avatar %>
<% end %>

### Step 3: 調整上傳圖片大小

# Gemflie
gem 'image_processing', '~> 1.2'
gem 'mini_magick', '~> 4.11'

# ubuntu
$ sudo apt install imagemagick

<% if @user.avatar.attached? %>
  <%= image_tag @user.avatar.variant(resize: '200x200') %>
<% end %>