README.md

zod-typed-form

This package helps you build typed data passed through forms using zod.

zodFormData

This function takes a zod schema and returns a zod schema with a preprocessor that allows it to validate FormData.

import { z } from "zod";

const schema = z.object({
  name: z.string(),
  age: z.number(),
});

const formSchema = zodFormData(schema);

const arbitraryInput = new FormData();
arbitraryInput.append("name", "John");
arbitraryInput.append("age", "42");

const me = formSchema.parse(arbitraryInput);

// `me` is now of type: { name: string, age: number }

createFormHelpers

This function takes a zod schema and returns a set of functions that help you build a form.

These function are "type-safe" meaning that they only allow you to pass fields that are defined in the schema.

They will not enforce adding required fields in the schema that are not present in the form.

import { z } from "zod";

const schema = z.object({
  name: z.string(),
  age: z.number(),
});

const { fieldName, useFieldValue } = createFormHelpers(schema);

const myNextJsPage = () => {
  const fieldValue = useFieldValue(useSearchParams());

  return (
    <form>
      <input name={fieldName("name")} defaultValue={fieldValue("name")} />
      <input
        type="number"
        name={fieldName("age")}
        defaultValue={fieldValue("age")}
      />
      <button type="submit">Submit</button>
    </form>
  );
};

parseAndRedirectOnError

This function is a helper function to validate formData against a schema, and redirect to the same form page if the validation fails. It automatically includes existing form fields in the query string to prefill forms and it includes error messages in the query string too.

import { zodFormData, parseAndRedirectOnError } from "zod-typed-form";

import { redirect } from "next/navigation";

const mySchema = zodFormData(
  z.object({
    name: z.string(),
    age: z.number(),
  })
);

async function onSubmit(formData: FormData) {
  "use server";

  const content = parseAndRedirectOnError({
    formData,
    schema: mySchema,
    redirect,
    redirectUrl: new URL(`https://example.com/path/to/form`),
    redirectParams: { hello: "world" },
  });

  // `content` is now of type: { name: string, age: number }
}