문제점

ActiveStorage를 사용하여 파일을 업로드할 때 "undefined method upload"for nil: NilClass"오류가 발생합니다.

재현 순서

Rails5.0 릴리즈에서 5.2

로 어플리케이션 업그레이드

실행rails active_storage:install 및 rails db:migrate ActiveStorage 설치

Mode, Controller, View에 파일 업로드에 필요한 설정 추가

브라우저에서 파일 업로드 작업을 수행할 때 문제점에 기재된 오류

까닭

ActiveStorage를 활용하는 데 필요한 설정 부족

해결책

environments/*.rb에 엔딩 추가

config/environments/development.rb

# Store uploaded files on the local file system (see config/storage.yml for options)
config.active_storage.service = :local

config/environments/test.rb

# Store uploaded files on the local file system (see config/storage.yml for options)
config.active_storage.service = :test

config/environments/production.rb

# Store uploaded files on the local file system (see config/storage.yml for options)
config.active_storage.service = :local

storage.yml 추가

config/storage.yml

test:
  service: Disk
  root: <%= Rails.root.join("tmp/storage") %>

local:
  service: Disk
  root: <%= Rails.root.join("storage") %>

# Use rails credentials:edit to set the AWS secrets (as aws:access_key_id|secret_access_key)
# amazon:
#   service: S3
#   access_key_id: <%= Rails.application.credentials.dig(:aws, :access_key_id) %>
#   secret_access_key: <%= Rails.application.credentials.dig(:aws, :secret_access_key) %>
#   region: us-east-1
#   bucket: your_own_bucket

# Remember not to checkin your GCS keyfile to a repository
# google:
#   service: GCS
#   project: your_project
#   credentials: <%= Rails.root.join("path/to/gcs.keyfile") %>
#   bucket: your_own_bucket

# Use rails credentials:edit to set the Azure Storage secret (as azure_storage:storage_access_key)
# microsoft:
#   service: AzureStorage
#   storage_account_name: your_account_name
#   storage_access_key: <%= Rails.application.credentials.dig(:azure_storage, :storage_access_key) %>
#   container: your_container_name

# mirror:
#   service: Mirror
#   primary: local
#   mirrors: [ amazon, google, microsoft ]

보태다

추가 설정 및 제작에 대한yaml,Rails5.2 새 프로그램의 기본 설정 파일 참조