Zod 데이터 변환과 세부 검증

Beyond Pass/Fail

The transform Method

const trimmed = z.string().transform((s) => s.trim());
trimmed.parse("  hi  "); // "hi"

Coercing Types

const page = z.coerce.number().int().positive();
page.parse("5"); // 5 as a number

Default Values

const schema = z.object({
  limit: z.number().default(20),
});
schema.parse({}); // { limit: 20 }

Custom Refinements

const password = z.string().refine(
  (val) => val.length >= 8,
  { message: "Too short" }
);

Cross-Field Validation

const form = z.object({
  pw: z.string(),
  confirm: z.string(),
}).refine((d) => d.pw === d.confirm, {
  message: "Passwords must match",
  path: ["confirm"],
});

superRefine for Multiple Errors

const s = z.string().superRefine((val, ctx) => {
  if (!/[A-Z]/.test(val)) ctx.addIssue({ code: "custom", message: "Need uppercase" });
  if (!/[0-9]/.test(val)) ctx.addIssue({ code: "custom", message: "Need digit" });
});

Chaining Transforms

const slug = z.string()
  .min(1)
  .transform((s) => s.toLowerCase().replace(/\s+/g, "-"));
slug.parse("Hello World"); // "hello-world"

Input vs Output Types

type In = z.input<typeof page>;   // string | number
type Out = z.output<typeof page>; // number

Safe Parsing

const r = password.safeParse("short");
if (!r.success) console.log(r.error.issues);

Pipe for Validate-then-Transform

const id = z.string().transform(Number).pipe(z.number().int());

Quick Check

Recap