Rails Active Storage

Attachment Types

• Use has_one_attached :avatar for single file fields
• Use has_many_attached :documents for collections
• Prefer descriptive names (e.g., profile_picture over image)

Validations

• Active Storage does not include file validations out of the box
• Validate presence, content type, and file size manually using custom validation methods
• Check avatar.attached? for presence and avatar.blob.content_type for format

Image Processing

• Use variant(resize_to_limit: [...]) for resizing
• Guard with representable? before calling .variant on non-image blobs
• Always check attached? before rendering