New on the blog: File Uploads in Wheels 4.0, the Idiomatic Way. <https://blog.wheels.dev/posts/file-uploads-in-wheels-4/ > Wheels 4.0 has no ActiveStorage-style attachment system — no

hasAttachment

, no upload service, no

params.file

. And that's fine. The honest idiomatic flow is five steps, and this post walks every one end to end. What it covers: • The multipart trap —

startFormTag

does NOT auto-add

enctype

just because a

fileField

is on the form. Default is

multipart=false

. Forget

multipart=true

and the upload fails silently — no error, file posts as plain text. This eats more uploads than everything else combined. •

fileField

vs

fileFieldTag

— bound (

user[avatar]

) vs unbound (

document

) field names, and why the name is your contract with the controller. • The controller — native CFML

cffile action="upload"

(Wheels has zero upload wrapper),

nameConflict="makeUnique"

, and copying the result onto

params.user

so the model can validate it. • Validation —

validatesFormatOf

over the stored string + a custom

validate()

callback for size/MIME, because validators can't see multipart uploads. •

sendFile

— the one direction with a real Wheels helper, with built-in path-traversal protection. Plus a "Sharp edges" section of real, source-confirmed gotchas.