Extend previous schema(s)

Sometimes it's useful to define an action "template" with a base input schema and then extend it with additional properties. This can be done inside the inputSchema() method by passing an async function that has the previous schema as its argument. See the example below:

"use server";

import { actionClient } from "@/lib/safe-action";
import { z } from "zod";

const inputSchema = z.object({
  username: z.string(),
});

const myAction = actionClient
  .inputSchema(inputSchema)
  .inputSchema(async (prevSchema) => {
    // Here we extend the previous schema with `password` property.
    return prevSchema.extend({ password: z.string() });
  })
  .inputSchema(async (prevSchema) => {
    // Here with `age` property.
    return prevSchema.extend({ age: z.number().positive() });
  })
  // `parsedInput` will be an object with `username`, `password` and `age` properties.
  .action(async ({ parsedInput: { username, password, age } }) => { 
    // Do something useful here...
  });

Note that if you don't use prevSchema inside the inputSchema() method, the previous schema(s) will be overwritten.