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React

Make Form Handling Easy in React Apps with Formik — Checkboxes and Radio Buttons

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Formik is a library that makes form handling in React apps easy.

In this article, we’ll look at how to handle form inputs with Formik.

Checkboxes

We can bind checkbox values to states with Formik.

For instance, we can write:

import React from "react";
import { Formik, Form, Field } from "formik";

export const FormExample = () => (
  <div>
    <Formik
      initialValues={{
        toggle: false,
        checked: []
      }}
      onSubmit={(values) => {
        alert(JSON.stringify(values, null, 2));
      }}
    >
      {({ values }) => (
        <Form>
          <label>
            <Field type="checkbox" name="toggle" />
            {`${values.toggle}`}
          </label>
          <div>Checked</div>
          <div>
            <label>
              <Field type="checkbox" name="checked" value="apple" />
              apple
            </label>
            <label>
              <Field type="checkbox" name="checked" value="orange" />
              orange
            </label>
            <label>
              <Field type="checkbox" name="checked" value="grape" />
              grape
            </label>
          </div>

          <button type="submit">Submit</button>
        </Form>
      )}
    </Formik>
  </div>
);
export default function App() {
  return (
    <div className="App">
      <FormExample />
    </div>
  );
}

We set the initialValues to what we want.

In the first Field component, we set name to 'toggle' to bind to the toggle field.

This will bind the checked value to the values.toggle property.

It’ll be true when it’s checked and false otherwise.

In the div, we have 3 Field components.

We set the value in addition to the name to let us populate the checked array with the value prop value of the checkboxes that are checked.

When we submit the form, we see the checked items in checked and toggle is either true or false depending on whether it’s checked or not.

Radio Buttons

Formik also makes binding states to radio buttons easy.

To do this, we write:

import React from "react";
import { Formik, Form, Field } from "formik";

export const FormExample = () => (
  <div>
    <Formik
      initialValues={{
        picked: ""
      }}
      onSubmit={(values) => {
        alert(JSON.stringify(values, null, 2));
      }}
    >
      {({ values }) => (
        <Form>
          <div>Picked</div>
          <div>
            <label>
              <Field type="radio" name="picked" value="apple" />
              One
            </label>
            <label>
              <Field type="radio" name="picked" value="orange" />
              Two
            </label>
            <div>Picked: {values.picked}</div>
          </div>

          <button type="submit">Submit</button>
        </Form>
      )}
    </Formik>
  </div>
);
export default function App() {
  return (
    <div className="App">
      <FormExample />
    </div>
  );
}

We set the name of the radio button groups to the same name.

And we also set the value for each.

Then we can pick one radio from the ones with the same name value.

And we’ll see the value with the value.picked property.

Conclusion

We can bind checkbox and radio button values to states with Formik.

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