[GO] Prepare a URL to display the image uploaded by Active Storage by yourself

What I wanted to do

I wanted to save the HTML including the image URL as it is in the DB and display it in raw with an editor such as WYSIWY.

problem

If you save the service_url directly, the access token will expire and you will get the following error:

https://storage.googleapis.com/xxx/6qk30zadasnfkansfalksj34gq?GoogleAccessId=...

<Error>
  <Code>ExpiredToken</Code>
  <Message>The provided token has expired.</Message>
  <Details>Request signature expired at: 2020-09-30T19:07:20+00:00</Details>
</Error>

Prepare the URL for generation

Create a model for assets to prepare a URL to generate and display a service_url with an access token.

asset.rb

class Asset < ApplicationRecord
  has_one_attached :image
end

Changed to send image data with show of controller.

assets_controller.rb

class AssetsController < ActionController::Base
  # GET /assets:id
  def show
    asset = Asset.find(params[:id])
    send_data asset.image.download, filename: asset.image.filename.to_s, content_type: asset.image.content_type
  end
end

By saving the following URL in the DB, it was possible to display the image via the application server without expiring.

...
<img src="http://localhost:3000/assets/2" alt="Image">
...