[Crystal Lang] Lucky Framework + Shrine File Uploader

00_shard.yml

crystal: 0.34.0

dependencies:
  lucky:
    github: luckyframework/lucky
    version: ~> 0.21
  shrine:
    github: jetrockets/shrine.cr
    version: ~> 0.8

01_config_shrine.cr

require "shrine"

Shrine.configure do |config|
  config.storages["cache"] = Shrine::Storage::FileSystem.new("uploads", prefix: "cache")
  config.storages["store"] = Shrine::Storage::FileSystem.new("uploads")
end

02_migration.cr

# db/migrations/20200614172421_create_file_imports.cr
class CreateFileImports::V20200614172421 < Avram::Migrator::Migration::V1
  def migrate
    # Learn about migrations at: https://luckyframework.org/guides/database/migrations
    create table_for(FileImport) do
      primary_key id : Int64
      add_timestamps
      add asset_data : JSON::Any?
      add_belongs_to post : Post, on_delete: :cascade
    end
  end

  def rollback
    drop table_for(FileImport)
  end
end

03_shards.cr

# src/shards.cr
# (at the bottom)
require "shrine"

04_post_action.cr

# given our `post` example, param_key will be `post`
file = params.nested_file?(:param_key)["image_attribute"]?
if file
  # file.name
  # "param_key:image_attribute"
  # file.tempfile
  #<File:/var/folders/41/g51hx5q90xqgk7wz9qv6738c0000gn/T/.3uQb3Bparam_key:image_attribute (closed)>

  SaveFileImport.create!(upload: file, post_id: post.id)
end

05_models_file_import.cr

# src/models/file_import.cr
class FileImport < BaseModel
  table do
    column asset_data : JSON::Any?

    belongs_to post : Post

    # Now `commentable` could be a `photo` or `video`
    polymorphic imageable, associations: [:post]
  end
  
  def blob_path
    if data = asset_data
      "/imports/#{data["id"].to_s}"
    else
      ""
    end
  end
end

05_models_post.cr

# src/models/post.cr
class Post < BaseModel
  table do
    # ..other fields..
    has_many images : FileImport
  end
end

06_operations_save_file_import.cr

# src/operations/save_file_import.cr
class FileImport::AssetUploader < Shrine
  def generate_location(io : IO | UploadedFile, metadata, context, **options)
    name = super(io, metadata, **options)

    File.join("imports", name)
  end
end

class SaveFileImport < FileImport::SaveOperation
  permit_columns asset_data
  needs upload : Lucky::UploadedFile
  @asset_changed : Bool? = nil
  property :asset_changed

  before_save do
    return true unless upload
    return true if asset_changed == false

    # do we need to create this new IO?
    upload_io = IO::Memory.new(File.read(upload.path))
    asset_data.value = convert_shrine_uploader(FileImport::AssetUploader.cache(upload_io))
    @asset_changed = true
  end

  after_save move_to_store

  def move_to_store(file_import : FileImport)
    if asset_changed == true && asset_data.value
      # do we need to create this new IO?
      upload_io = IO::Memory.new(File.read(upload.path))
      asset_data.value = convert_shrine_uploader(FileImport::AssetUploader.store(upload_io, move: true, context: { model: file_import }))
      @asset_changed = false
      save!
    end
    true
  end

  def convert_shrine_uploader(uploader : Shrine::UploadedFile) : JSON::Any
    JSON.parse(uploader.data.to_json)
  end
end

07_show_post_page.cr

# in some post show page
post.images.each do |image|
  if image && (asset_data = image.asset_data)
    img src: image.blob_path
  else
    text "No Image"
  end
end

07_update_post_page.cr

# in some post update (with form)
def render_post_form(op)
  form_for Post::Update.with(@post.id), enctype: "multipart/form-data" do
    # some fields...
    file_input(op.image_attribute, attrs: [:required]
    # ...some fields

    submit "Update", data_disable_with: "Updating..."
  end
end