Schemas kombinieren und verfeinern

import { z } from "zod";
const base = z.object({ name: z.string() });
// We will add rules and combine schemas from here.

import { z } from "zod";
const password = z.string().refine(
  (s) => s.length >= 8,
  { message: "Must be at least 8 characters" }
);
// password.parse("short") throws with that message.

import { z } from "zod";
const form = z.object({
  password: z.string(),
  confirm: z.string()
}).refine((d) => d.password === d.confirm, {
  message: "Passwords must match"
});
// Validates both fields together.

import { z } from "zod";
const trimmed = z.string().transform((s) => s.trim());
const result = trimmed.parse("  hi  "); // "hi"

import { z } from "zod";
const schema = z.object({
  name: z.string(),
  bio: z.string().optional()
});
// bio may be omitted.

import { z } from "zod";
const schema = z.object({
  retries: z.number().default(3)
});
const r = schema.parse({}); // { retries: 3 }

import { z } from "zod";
const id = z.union([z.string(), z.number()]);
// id.parse("abc") and id.parse(123) both succeed.

import { z } from "zod";
const shape = z.discriminatedUnion("kind", [
  z.object({ kind: z.literal("circle"), radius: z.number() }),
  z.object({ kind: z.literal("square"), side: z.number() })
]);
// Picks the right member by kind.

import { z } from "zod";
const base = z.object({ id: z.number() });
const user = base.extend({ name: z.string() });
// user validates { id: number; name: string }

import { z } from "zod";
const a = z.object({ x: z.number() });
const b = z.object({ y: z.string() });
const combined = a.merge(b);
// combined validates { x: number; y: string }

import { z } from "zod";
const signup = z.object({
  email: z.string().refine(s => s.includes("@"), { message: "Invalid email" }),
  age: z.number().default(18)
}).extend({
  newsletter: z.boolean().optional()
});
// One schema, many rules.

import { z } from "zod";
const schema = z.object({ name: z.string() })
  .extend({ age: z.number().default(0) })
  .refine(d => d.name.length > 0, { message: "Name required" });
// Composed validation in one place.