Remove Form.create#

Form of v4 does not need to create context by calling Form.create(). Form now has it's own data scope and you don't need getFieldDecorator anymore. Just use Form.Item directly:

// antd v3
const Demo = ({ form: { getFieldDecorator } }) => (
  <Form>
    <Form.Item>
      {getFieldDecorator('username', {
        rules: [{ required: true }],
      })(<Input />)}
    </Form.Item>
  </Form>
);

const WrappedDemo = Form.create()(Demo);

To:

// antd v4
const Demo = () => (
  <Form>
    <Form.Item name="username" rules={[{ required: true }]}>
      <Input />
    </Form.Item>
  </Form>
);

Since Form.create() is removed, methods like onFieldsChange have moved to Form and form state is controlled by a fields prop. ref example。

Form control#

If you want to control form, you can use Form.useForm() to create Form instance for operation:

// antd v3
const Demo = ({ form: { setFieldsValue } }) => {
  React.useEffect(() => {
    setFieldsValue({
      username: 'Bamboo',
    });
  }, []);

  return (
    <Form>
      <Form.Item>
        {getFieldDecorator('username', {
          rules: [{ required: true }],
        })(<Input />)}
      </Form.Item>
    </Form>
  );
};

const WrappedDemo = Form.create()(Demo);

To:

// antd v4
const Demo = () => {
  const [form] = Form.useForm();

  React.useEffect(() => {
    form.setFieldsValue({
      username: 'Bamboo',
    });
  }, []);

  return (
    <Form form={form}>
      <Form.Item name="username" rules={[{ required: true }]}>
        <Input />
      </Form.Item>
    </Form>
  );
};

For class component, you can use ref to access instance:

// antd v4
class Demo extends React.Component {
  formRef = React.createRef();

  componentDidMount() {
    this.formRef.current.setFieldsValue({
      username: 'Bamboo',
    });
  }

  render() {
    return (
      <Form ref={this.formRef}>
        <Form.Item name="username" rules={[{ required: true }]}>
          <Input />
        </Form.Item>
      </Form>
    );
  }
}

If you don't want to use the Item style, you can use noStyle prop to remove it:

// antd v3
const Demo = ({ form: { getFieldDecorator } }) => {
  return <Form>{getFieldDecorator('username')(<Input />)}</Form>;
};

const WrappedDemo = Form.create()(Demo);

To:

// antd v4
const Demo = () => {
  return (
    <Form>
      <Form.Item name="username" noStyle>
        <Input />
      </Form.Item>
    </Form>
  );
};

Linkage with field#

New Form uses incremental update which only updates related field. So if there is some linkage between fields or updates with the whole form, you can use dependencies or shouldUpdate to handle that.

replace onSubmit with onFinish#

You need to listen to onSubmit and call validateFields to handle validation in old Form. New Form provides onFinish which will only trigger when validation has passed:

// antd v3
const Demo = ({ form: { getFieldDecorator, validateFields } }) => {
  const onSubmit = e => {
    e.preventDefault();
    validateFields((err, values) => {
      if (!err) {
        console.log('Received values of form: ', values);
      }
    });
  };

  return (
    <Form onSubmit={onSubmit}>
      <Form.Item>
        {getFieldDecorator('username', {
          rules: [{ required: true }],
        })(<Input />)}
      </Form.Item>
    </Form>
  );
};

const WrappedDemo = Form.create()(Demo);

To:

// antd v4
const Demo = () => {
  const onFinish = values => {
    console.log('Received values of form: ', values);
  };

  return (
    <Form onFinish={onFinish}>
      <Form.Item name="username" rules={[{ required: true }]}>
        <Input />
      </Form.Item>
    </Form>
  );
};

Replace validateFieldsAndScroll with scrollToField#

New version recommend use onFinish for submit after validation. Thus validateFieldsAndScroll is changed to more flexible method scrollToField:

// antd v3
onSubmit = () => {
  form.validateFieldsAndScroll((error, values) => {
    // Your logic
  });
};

To:

// antd v4
onFinishFailed = ({ errorFields }) => {
  form.scrollToField(errorFields[0].name);
};

Initialization#

Besides, we move initialValue into Form to avoid field with same name both using initialValue to cause conflict:

// antd v3
const Demo = ({ form: { getFieldDecorator } }) => (
  <Form>
    <Form.Item>
      {getFieldDecorator('username', {
        rules: [{ required: true }],
        initialValue: 'Bamboo',
      })(<Input />)}
    </Form.Item>
  </Form>
);

const WrappedDemo = Form.create()(Demo);

To:

// antd v4
const Demo = () => (
  <Form initialValues={{ username: 'Bamboo' }}>
    <Form.Item name="username" rules={[{ required: true }]}>
      <Input />
    </Form.Item>
  </Form>
);

In v3, modifying the initialValue of un-operated field will update the field value synchronously, which is a bug. However, since it has been used as a feature for a long time, we have not fixed it. In v4, the bug has been fixed. initialValues only takes effect when initializing and resetting the form.

Nested field paths using arrays#

In the past versions we used . to represent nested paths (such as user.name to represent { user: { name: '' } }). However, in some backend systems, . is also included in the variable name. This causes the user to need additional code to convert, so in the new version, nested paths are represented by arrays to avoid unexpected behavior (eg ['user', 'name']).

Therefore, paths returned by methods such as getFieldsError are always in an array form for the user to handle:

form.getFieldsError();

/*
[
  { name: ['user', 'name'], errors: [] },
  { name: ['user', 'age'], errors: ['Some error message'] },
]
*/

Nested field definition has changed from:

// antd v3
<Form.Item label="Firstname">{getFieldDecorator('user.0.firstname', {})(<Input />)}</Form.Item>

To

// antd v4
<Form.Item name={['user', 0, 'firstname']} label="Firstname">
  <Input />
</Form.Item>

Similarly using setFieldsValue has changed from:

// antd v3
this.formRef.current.setFieldsValue({
  'user.0.firstname': 'John',
});

To

// antd v4
this.formRef.current.setFieldsValue({
  user: [
    {
      firstname: 'John',
    },
  ],
});

Remove callback in validateFields#

validateFields will return a Promise, so you can handle the error with async/await or then/catch. It is no longer necessary to determine if errors is empty:

// antd v3
validateFields((err, value) => {
  if (!err) {
    // Do something with value
  }
});

To

// antd v4
validateFields().then(values => {
  // Do something with value
});