gem-hunter

Type-safe <form> for React using Zod!

Features / opinions

• 🔥 NEW experimental automatic progressive HTML attributes helper
  • Docs and feedback here.
• 💎 Type-safe
  • Get form data as a typed object
  • Typo-safe name and id attribute generation
• 🤯 Simple nested object and array fields
  • And still type-safe!
• ✅ Validation on the client and the server
  • With FormData or JSON
  • Eg. works with any JavaScript backend
  • Remix, Next.js, Express, Node.js, CF Workers, Deno etc.
• 📦 Tiny: Less than 3kb (minified & gzipped)
  • 🌳 Tree shakes to be even smaller!
  • 🤷 No dependencies, only peer deps for React and Zod
• 🛑 No controlled inputs or context providers required
  • ☝️ The form is validated directly from the <form> DOM element
  • 🚀 As performant as React form libraries can get!

If you enjoy this lib a Twitter shout-out @esamatti is always welcome! 😊

You can also checkout my talk at React Finland 2022. Slides.

npm install react-zorm

Also on Codesandbox!

import { z } from "zod";
import { useZorm } from "react-zorm";

const FormSchema = z.object({
    name: z.string().min(1),
    password: z
        .string()
        .min(10)
        .refine((pw) => /[0-9]/.test(pw), "Password must contain a number"),
});

function Signup() {
    const zo = useZorm("signup", FormSchema, {
        onValidSubmit(e) {
            e.preventDefault();
            alert("Form ok!\n" + JSON.stringify(e.data, null, 2));
        },
    });
    const disabled = zo.validation?.success === false;

    return (
        <form ref={zo.ref}>
            Name:
            <input
                type="text"
                name={zo.fields.name()}
                className={zo.errors.name("errored")}
            />
            {zo.errors.name((e) => (
                <ErrorMessage message={e.message} />
            ))}
            Password:
            <input
                type="password"
                name={zo.fields.password()}
                className={zo.errors.password("errored")}
            />
            {zo.errors.password((e) => (
                <ErrorMessage message={e.message} />
            ))}
            <button disabled={disabled} type="submit">
                Signup!
            </button>
            <pre>Validation status: {JSON.stringify(zo.validation, null, 2)}</pre>
        </form>
    );
}

Also checkout this classic TODOs example demonstrating almost every feature in the library and if you are in to Remix checkout this server-side validation example.

Create a Zod type with a nested object

const FormSchema = z.object({
    user: z.object({
        email: z.string().min(1),
        password: z.string().min(8),
    }),
});

and just create the input names with .user.:

<input type="text" name={zo.fields.user.email()} />;
<input type="password" name={zo.fields.user.password()} />;

Array of user objects for example:

const FormSchema = z.object({
    users: z.array(
        z.object({
            email: z.string().min(1),
            password: z.string().min(8),
        }),
    ),
});

and put the array index to users(index):

users.map((user, index) => {
    return (
        <>
            <input type="text" name={zo.fields.users(index).email()} />
            <input type="password" name={zo.fields.users(index).password()} />
        </>
    );
});

And all this is type checked 👌

See the TODOs example for more details

This is Remix but React Zorm does not actually use any Remix APIs so this method can be adapted for any JavaScript based server.

import { parseForm } from "react-zorm";

export let action: ActionFunction = async ({ request }) => {
    const form = await request.formData();
    // Get parsed and typed form object. This throws on validation errors.
    const data = parseForm(FormSchema, form);
};

The useZorm() hook can take in any additional ZodIssues via the customIssues option:

const zo = useZorm("signup", FormSchema, {
    customIssues: [
        {
            code: "custom",
            path: ["username"],
            message: "The username is already in use",
        },
    ],
});

These issues can be generated anywhere. Most commonly on the server. The error chain will render these issues on the matching paths just like the errors coming from the schema.

To make their generation type-safe react-zorm exports createCustomIssues() chain to make it easy:

const issues = createCustomIssues(FormSchema);

issues.username("Username already in use");

const zo = useZorm("signup", FormSchema, {
    customIssues: issues.toArray(),
});

This code is very contrived but take a look at these examples:

• Rendering field errors from the Remix Action Functions
• Async validation via React Query

The chains are a way to access the form validation state in a type safe way. The invocation via () returns the chain value. On the fields chain the value is the name input attribute and the errors chain it is the possible ZodIssue object for the field.

There few other option for invoking the chain:

Return values for different invocation types

• ("name"): string - The name attribute value
• ("id"): string - Unique id attribute value to be used with labels and aria-describedby
• (): string - The default, same as "name"
• (index: number): FieldChain - Special case for setting array indices
• (fn: RenderFunction): any - Calls the function with {name: string, id: string, type: ZodType, issues: ZodIssue} and renders the return value.
  • Can be used to create resuable fields. Codesandbox example.

• (): ZodIssue | undefined - Possible ZodIssue object
• (value: T): T | undefined - Return the passed value on error. Useful for setting class names for example
• (value: typeof Boolean): boolean - Return true when there's an error and false when it is ok. Example .field(Boolean).
• <T>(render: (issue: ZodIssue, ...otherIssues: ZodIssue[]) => T): T | undefined - Invoke the passed function with the ZodIssue and return its return value. When there's no error a undefined is returned and the function will not be invoked. Useful for rendering error message components. One field can have multiple issues so to render them all you can use the spread operator ...issues.
• (index: number): ErrorChain - Special case for accessing array elements

The first tool you should reach is React. Just make the input controlled with useState(). This works just fine with checkboxes, radio buttons and even with text inputs when the form is small. React Zorm is not really interested how the inputs get on the form. It just reads the value attributes using the platform form APIs (FormData).

But if you have a larger form where you need to read the input value and you find it too heavy to read it with just useState() you can use useValue() from Zorm.

import { useValue } from "react-zorm";

function Form() {
    const zo = useZorm("form", FormSchema);
    const value = useValue({ zorm: zo, name: zo.fields.input() });
    return <form ref={zo.ref}>...</form>;
}

useValue() works by subscribing to the input DOM events and syncing the value to a local state. But this does not fix the performance issue yet. You need to move the useValue() call to a subcomponent to avoid rendering the whole form on every input change. See the Zorm type docs on how to do this.

Alternatively you can use the <Value> wrapper which allows access to the input value via render prop:

import { Value } from "react-zorm";

function Form() {
    const zo = useZorm("form", FormSchema);
    return (
        <form ref={zo.ref}>
            <input type="text" name={zo.fields.input()} />
            <Value form={zo.ref} name={zo.fields.input()}>
                {(value) => <span>Input value: {value}</span>}
            </Value>
        </form>
    );
}

This way only the inner <span> element renders on the input changes.

Here's a codesandox demonstrating these and vizualizing the renders.

When the form submits and on input blurs after the first submit attempt.

If you want total control over this, pass in setupListeners: false and call validate() manually when you need. Note that now you need to manually prevent submitting when the form is invalid.

function Signup() {
    const zo = useZorm("signup", FormSchema, { setupListeners: false });

    return (
        <form
            ref={zo.ref}
            onSubmit={(e) => {
                const validation = zo.validate();

                if (!validation.success) {
                    e.preventDefault();
                }
            }}
        >
            ...
        </form>
    );
}

That do not create <input> elements?

Since Zorm just works with the native <form> you must sync their state to <input type="hidden"> elements in order for them to become actually part of the form.

Here's a Codesandbox example with react-select.

Another more modern option is to use the formdata event. Codesandbox example

See https://twitter.com/esamatti/status/1488553690613039108

Use the ZodIssue's .code properties to render corresponding error messages based on the current language instead of just rendering the .message.

See this Codesandbox example:

https://codesandbox.io/s/github/esamattis/react-zorm/tree/master/packages/codesandboxes/boxes/internalization?file=/src/App.tsx

Checkboxes can result to simple booleans or arrays of selected values. These custom Zod types can help with them. See this usage example.

const booleanCheckbox = () =>
    z
        .string()
        // Unchecked checkbox is just missing so it must be optional
        .optional()
        // Transform the value to boolean
        .transform(Boolean);

const arrayCheckbox = () =>
    z
        .array(z.string().nullish())
        .nullish()
        // Remove all nulls to ensure string[]
        .transform((a) => (a ?? []).flatMap((item) => (item ? item : [])));

If your server does not support parsing form data to the standard FormData you can post the form as JSON and just use .parse() from the Zod schema. See the next section for JSON posting.

Prevent the default submission in onValidSubmit() and use fetch():

const zo = useZorm("todos", FormSchema, {
    onValidSubmit: async (event) => {
        event.preventDefault();
        await fetch("/api/form-handler", {
            method: "POST",
            headers: {
                "Content-Type": "application/json",
            },
            body: JSON.stringify(event.data),
        });
    },
});

If you need loading states React Query mutations can be cool:

import { useMutation } from "react-query";

// ...

const formPost = useMutation((data) => {
    return fetch("/api/form-handler", {
        headers: {
            "Content-Type": "application/json",
        },
        body: JSON.stringify(data),
    });
});

const zo = useZorm("todos", FormSchema, {
    onValidSubmit: async (event) => {
        event.preventDefault();
        formPost.mutate(event.data);
    },
});

return formPost.isLoading ? "Sending..." : null;

Use z.instanceof(File) for the file input type. See this Codesandox for an example.

Native forms support files as is but if you need to POST as JSON you can turn the file to a base64 for example. See FileReader.readAsDataURL(). Or just post the file separately.

Tools available for importing from "react-zorm"

Create a form Validator

The form name. This used for the input id generation so it should be unique string within your forms.

Zod schema to parse the form with.

• onValidSubmit(event: ValidSubmitEvent): any: Called when the form is submitted with valid data
  • ValidSubmitEvent#data: The Zod parsed form data
  • ValidSubmitEvent#target: The form HTML Element
  • ValidSubmitEvent#preventDefault(): Prevent the default form submission
• setupListeners: boolean: Do not setup any listeners. Ie. onValidSubmit won't be called nor the submission is automatically prevented. This gives total control when to validate the form. Set your own onSubmit on the form etc. Defaults to true.
• customIssues: ZodIssue[]: Any additional ZodIssue to be rendered within the error chain. This is commonly used to handle server-side field validation
• onFormData(event: FormDataEvent): Convinience callback for accessing the formdata event because React does not support it directly on the in JSX. This can be used to modify the outgoing form without modifying the form on the DOM. See this Codesandbox example on how it can used to handle controlled components.

• ref: A callback ref for the <form> element
• form: The current form element set by the callback ref
• validation: SafeParseReturnType | null: The current Zod validation status returned by safeParse()
• validate(): SafeParseReturnType: Manually invoke validation
• fields: FieldChain: The fields chain
• errors: ErroChain: The error chain

The type of the object returned by useZorm(). This type object can be used to type component props if you want to split the form to multiple components and pass the zorm object around.

import type { Zorm } from "react-zorm";

function MyForm() {
    const zo = useZorm("signup", FormSchema);

    return (
        // ...
        <SubComponent zorm={zo} />
        //..
    );
}

function SubComponent(props: { zorm: Zorm<typeof FormSchema> }) {
    // ...
}

Get live raw value from the input.

• form: RefObject<HTMLFormElement>: The form ref from zo.ref
• initialValue: string: Initial value on the first and ssr render
• transform(value: string): any: Transform the value before setting it to the internal state. The type can be also changed.

Render prop version of the useValue() hook. The props are ValueSubscription. The render prop child is (value: string) => ReactNode.

<Value zorm={zo} name={zo.fields.input()}>
    {(value) => <>value</>}
</Value>

Parse HTMLFormElement or FormData with the given Zod schema.

Like parseForm() but uses the safeParse() method from Zod.