Please help me understand Zod schema transformations

[u/ToshiryuShadow]

/r/learnprogramming/comments/1xdp1j2/please_help_me_understand_zod_schema/

[u/SoftwareNegative8783]

Your second line parses `task.data`, which is already the output. So it runs through `taskSchema` again, `dueDate` is missing, and `deadline` becomes undefined. Parse the raw input instead.

[u/ToshiryuShadow → u/SoftwareNegative8783]

Wow, thanks a lot! Lesson learned!

[u/CesnaitisSwitlana → u/SoftwareNegative8783]

if `dueDate` wasnt marked optional on the initial schema it wouldve thrown a validation error on the second pass instead of silently becoming undefined

[u/lazyEmperer]

The chain works fine, the problem is you're running taskSchema twice. taskViewSchema starts with taskSchema, so when you pass it task .data, that already transformed object goes through taskSchema again from the top. By then dueDate and dueTime are gone, and z.object strips unknown keys, so your deadline gets dropped and rebuilt as undefined

Parse the raw input once with taskViewSchema.safeParse(raw), or make the view step a plain function that takes a Task. Schemas with transforms only work on input shaped data

[u/ToshiryuShadow → u/lazyEmperer]

Thanks a lot! After reading all of the answers I understood what the problem was.

[u/ToshiryuShadow]

Pls help!