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使用表单状态构建多步骤表单

使用状态中的步骤计数器将较长的注册表单拆分为多个步骤，并在进入下一步前仅验证当前步骤的字段。

使用表单状态构建多步骤表单 是 CoddyKit 上的免费 React Native Academy 课时。 这是第 3 节课，共 4 节。 你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。 这是 React Native Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 React Native Academy 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

What Is a Multi-Step Form?

A multi-step form breaks a long registration or checkout flow into discrete, manageable steps — typically 2 to 5 screens. Each step focuses on a related group of fields, reducing cognitive load and improving completion rates compared to a single long scroll. Common examples include onboarding wizards, address-plus-payment checkout flows, and multi-stage profile setup.

Sharing One Form Instance Across Steps

The key to a multi-step form with react-hook-form is to create one useForm instance for the entire form and pass control and errors down as props to each step component. This keeps all field values and validation state in one place. Values entered on step 1 remain available when the user reaches step 3, and submitting the final step accesses the complete form data.

interface RegisterForm {
  name: string;
  email: string;
  password: string;
  phone: string;
  city: string;
}

export default function RegisterScreen() {
  const [step, setStep] = React.useState(1);
  const form = useForm<RegisterForm>({ defaultValues: { name: '', email: '', password: '', phone: '', city: '' } });

  return (
    <View style={styles.container}>
      {step === 1 && <Step1AccountInfo form={form} />}
      {step === 2 && <Step2ContactDetails form={form} />}
      {step === 3 && <Step3Review form={form} onSubmit={handleFinalSubmit} />}
    </View>
  );
}

Defining Step Component Props

Each step component receives the form instance as a prop. Define a TypeScript type for the prop using UseFormReturn from react-hook-form. This gives the step component access to control, formState.errors, trigger, and watch — all the tools needed to render and validate its own subset of fields.

import type { UseFormReturn } from 'react-hook-form';

interface StepProps {
  form: UseFormReturn<RegisterForm>;
  onNext?: () => void;
}

export function Step1AccountInfo({ form, onNext }: StepProps) {
  const { control, formState: { errors } } = form;
  // Render only name, email, and password fields
}

Validating Only the Current Step

Before advancing to the next step, validate only the fields on the current step using form.trigger(['fieldA', 'fieldB']). This runs validation on the specified fields and returns a Promise that resolves to true if all are valid. If any fail, the errors appear and the user cannot advance until they are fixed. Fields on later steps are not validated yet.

async function handleNext() {
  const step1Fields: (keyof RegisterForm)[] = ['name', 'email', 'password'];
  const isValid = await form.trigger(step1Fields);
  if (isValid) {
    setStep(2);
  }
  // If invalid, formState.errors is populated for the listed fields
}

Progress Indicator UI

Add a visual progress bar or step indicator at the top of the screen so users know how far along they are. Calculate progress as (currentStep / totalSteps) * 100. A simple progress bar using an animated View width gives clear feedback and sets expectations about how much more is required before they can complete the form.

const TOTAL_STEPS = 3;

function ProgressBar({ current }: { current: number }) {
  const progress = (current / TOTAL_STEPS) * 100;
  return (
    <View style={styles.progressContainer}>
      <View style={[styles.progressFill, { width: progress + '%' }]} />
    </View>
  );
}

// Usage:
<ProgressBar current={step} />

Navigating Between Steps

Use a step counter in useState to track the current step. 'Next' buttons validate the current step's fields with trigger before incrementing the step. 'Back' buttons decrement the step without re-validating. Always disable the 'Next' button or show a loading spinner while async validation (like username availability checks) is in progress.

const { formState: { isValidating } } = form;

function NavigationButtons() {
  return (
    <View style={styles.navRow}>
      {step > 1 && (
        <Button title='Back' onPress={() => setStep((s) => s - 1)} />
      )}
      {step < TOTAL_STEPS ? (
        <Button
          title={isValidating ? 'Checking...' : 'Next'}
          onPress={handleNext}
          disabled={isValidating}
        />
      ) : (
        <Button title='Submit' onPress={form.handleSubmit(onFinalSubmit)} />
      )}
    </View>
  );
}

Reviewing Entered Data on the Final Step

The final step is often a review screen where users confirm their entries before submitting. Use form.getValues() to read all field values and display them in a summary list. This gives users one last chance to catch typos before the data is sent to the server, reducing support requests and user errors.

function Step3Review({ form, onSubmit }: StepProps) {
  const values = form.getValues();

  return (
    <ScrollView>
      <Text>Review your information:</Text>
      <Text>Name: {values.name}</Text>
      <Text>Email: {values.email}</Text>
      <Text>Phone: {values.phone}</Text>
      <Text>City: {values.city}</Text>
      <Button title='Confirm and Register' onPress={onSubmit} />
    </ScrollView>
  );
}

Using formState.isSubmitting

formState.isSubmitting is true while handleSubmit's async callback is running. Use it to disable the submit button and show a loading spinner during the API call. This prevents double-submissions when the user taps quickly and gives clear feedback that the form is being processed.

const { formState: { isSubmitting } } = form;

<Button
  title={isSubmitting ? 'Submitting...' : 'Confirm and Register'}
  onPress={form.handleSubmit(onFinalSubmit)}
  disabled={isSubmitting}
/>

Persisting Step Data Across Navigation

If users navigate away from the multi-step form and return later, use Zustand or React Navigation's route params to preserve the current step and partially filled form data. Combine this with react-hook-form's reset(savedValues) to restore the form to where the user left off. This dramatically reduces form abandonment on mobile.

// On unmount or navigation away:
useEffect(() => {
  return () => {
    const currentValues = form.getValues();
    useFormDraftStore.getState().saveDraft(currentValues, step);
  };
}, []);

// On mount, restore if draft exists:
useEffect(() => {
  const draft = useFormDraftStore.getState().draft;
  if (draft) {
    form.reset(draft.values);
    setStep(draft.step);
  }
}, []);

Keyboard Navigation Between Fields

On mobile, tapping 'Next' on the keyboard should move focus to the next input within a step. Use useRef to hold refs for each TextInput and call ref.current.focus() in the onSubmitEditing callback of each input. Set returnKeyType='next' on intermediate fields and 'done' on the last field of each step.

const emailRef = React.useRef<TextInput>(null);
const passwordRef = React.useRef<TextInput>(null);

<TextInput
  placeholder='Full Name'
  returnKeyType='next'
  onSubmitEditing={() => emailRef.current?.focus()}
/>
<TextInput
  ref={emailRef}
  placeholder='Email'
  returnKeyType='next'
  onSubmitEditing={() => passwordRef.current?.focus()}
/>
<TextInput
  ref={passwordRef}
  placeholder='Password'
  returnKeyType='done'
  onSubmitEditing={handleNext}
  secureTextEntry
/>

Handling Back Navigation Safely

When the user presses the hardware back button on Android or swipes back on iOS, handle it to decrement the step counter instead of leaving the screen entirely. Use useFocusEffect with a BackHandler to intercept the hardware back event. If the user is on step 1, allow normal navigation back to the previous screen.

import { BackHandler } from 'react-native';
import { useFocusEffect } from '@react-navigation/native';

useFocusEffect(
  React.useCallback(() => {
    const handler = BackHandler.addEventListener('hardwareBackPress', () => {
      if (step > 1) {
        setStep((s) => s - 1);
        return true; // prevent default back navigation
      }
      return false; // allow default (exit screen)
    });
    return () => handler.remove();
  }, [step])
);

Quick Check

Test your understanding of React Native Mobile Development concepts from this lesson.

Lesson Recap

In this lesson you learned: one useForm instance shared across all steps keeps form data and validation state unified, trigger with specific field names validates only the current step before advancing, and formState.isSubmitting disables the submit button during the final API call to prevent duplicate submissions. Next up we explore submitting and resetting forms.

常见问题解答

「使用表单状态构建多步骤表单」课时是免费的吗？

是的 — 「使用表单状态构建多步骤表单」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 React Native Academy 课程的其余内容，请升级到 CoddyKit PRO。 React Native Academy 课程共包含 4 节课。

「使用表单状态构建多步骤表单」这节课中我会学到什么？

使用状态中的步骤计数器将较长的注册表单拆分为多个步骤，并在进入下一步前仅验证当前步骤的字段。 你通过在浏览器中直接运行的动手代码来练习 React Native Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 React Native Academy 需要有经验吗？

无需任何先前经验。CoddyKit 上的 React Native Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。 这是第 3 节课，共 4 节。

「使用表单状态构建多步骤表单」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 React Native Academy 课中编写并运行代码吗？

能。每节 React Native Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

此课程中的所有课时

  1. 使用 Controller 设置 react-hook-form
  2. 验证规则与错误消息
  3. 使用表单状态构建多步骤表单
  4. 提交与重置表单
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