使用 Formik 向导访问上一步中的值

如何解决使用 Formik 向导访问上一步中的值

我正在使用 Formik's Wizard component 创建一个多步骤表单。我不知道如何访问前一个 <WizardStep /> 中的值。例如，在步骤 1 中有 firstName 和 lastName 的字段。是否可以在第二步中读取这些值？

所有值都在第二步 onSubmit 中打印，但如何在实际的 <WizardStep /> 组件中访问它们？

基本上如何将 props 传递给下一个 <WizardStep />

Codesandbox here

import React,{ useState } from 'react';
import { ErrorMessage,Field,Form,Formik } from 'formik';
import * as Yup from 'yup';
import { Debug } from './Debug';

const sleep = ms => new Promise(resolve => setTimeout(resolve,ms));

// Wizard is a single Formik instance whose children are each page of the
// multi-step form. The form is submitted on each forward transition (can only
// progress with valid input),whereas a backwards step is allowed with
// incomplete data. A snapshot of form state is used as initialValues after each
// transition. Each page has an optional submit handler,and the top-level
// submit is called when the final page is submitted.
const Wizard = ({ children,initialValues,onSubmit }) => {
  const [stepNumber,setStepNumber] = useState(0);
  const steps = React.Children.toArray(children);
  const [snapshot,setSnapshot] = useState(initialValues);

  const step = steps[stepNumber];
  const totalSteps = steps.length;
  const isLastStep = stepNumber === totalSteps - 1;

  const next = values => {
    setSnapshot(values);
    setStepNumber(Math.min(stepNumber + 1,totalSteps - 1));
  };

  const previous = values => {
    setSnapshot(values);
    setStepNumber(Math.max(stepNumber - 1,0));
  };

  const handleSubmit = async (values,bag) => {
    if (step.props.onSubmit) {
      await step.props.onSubmit(values,bag);
    }
    if (isLastStep) {
      return onSubmit(values,bag);
    } else {
      bag.setTouched({});
      next(values);
    }
  };

  return (
    <Formik
      initialValues={snapshot}
      onSubmit={handleSubmit}
      validationSchema={step.props.validationSchema}
    >
      {formik => (
        <Form>
          <p>
            Step {stepNumber + 1} of {totalSteps}
          </p>
          {step}
          <div style={{ display: 'flex' }}>
            {stepNumber > 0 && (
              <button onClick={() => previous(formik.values)} type="button">
                Back
              </button>
            )}
            <div>
              <button disabled={formik.isSubmitting} type="submit">
                {isLastStep ? 'Submit' : 'Next'}
              </button>
            </div>
          </div>
          <Debug />
        </Form>
      )}
    </Formik>
  );
};

const WizardStep = ({ children }) => children;

const App = () => (
  <div>
    <h1>Formik Multistep Wizard</h1>
    <Wizard
      initialValues={{
        email: '',firstName: '',lastName: '',}}
      onSubmit={async values =>
        sleep(300).then(() => console.log('Wizard submit',values))
      }
    >
      <WizardStep
        onSubmit={() => console.log('Step1 onSubmit')}
        validationSchema={Yup.object({
          firstName: Yup.string().required('required'),lastName: Yup.string().required('required'),})}
      >
        <div>
          <label htmlFor="firstName">First Name</label>
          <Field
            autoComplete="given-name"
            component="input"
            id="firstName"
            name="firstName"
            placeholder="First Name"
            type="text"
          />
          <ErrorMessage className="error" component="div" name="firstName" />
        </div>
        <div>
          <label htmlFor="lastName">Last Name</label>
          <Field
            autoComplete="family-name"
            component="input"
            id="lastName"
            name="lastName"
            placeholder="Last Name"
            type="text"
          />
          <ErrorMessage className="error" component="div" name="lastName" />
        </div>
      </WizardStep>
      <WizardStep
        onSubmit={() => console.log('Step2 onSubmit')}
        validationSchema={Yup.object({
          email: Yup.string()
            .email('Invalid email address')
            .required('required'),})}
      >
        <div>
          <label htmlFor="email">Email</label>
          <Field
            autoComplete="email"
            component="input"
            id="email"
            name="email"
            placeholder="Email"
            type="text"
          />
          <ErrorMessage className="error" component="div" name="email" />
        </div>
      </WizardStep>
    </Wizard>
  </div>
);

export default App;

解决方法

您可以为此使用 React 上下文或 Redux。下面是如何使用 React Context 做到这一点。

第 1 步：创建一个“提供者”，它将成为所有向导步骤的状态容器。它非常简单，只包含一个状态。

const WizardContext = createContext();

const WizardProvider = ({ children }) => {
  const [wizardState,setWizardState] = useState({});

  const value = useMemo(() => [wizardState,setWizardState],[
    wizardState,setWizardState
  ]);

  return (
    <WizardContext.Provider value={value}>{children}</WizardContext.Provider>
  );
};

const useWizardContext = () => useContext(WizardContext);

第 2 步：修复您的 App 组件并将其内容包装在提供程序中：

const App = () => (
  <div>
    <h1>Formik Multistep Wizard</h1>
    <WizardProvider>
      <AppContainer />
    </WizardProvider>
  </div>
);

第 3 步：按以下方式使用向导上下文。基本上，通过 setWizardState 函数控制全局状态并通过 wizardState 访问它。

const AppContainer = () => {
  const [wizardState,setWizardState] = useWizardContext();
  
  return (
    <Wizard .....>
      <WizardStep onSubmit={(values) => {
          setWizardState(values);
          console.log("Step1 onSubmit");
        }}></WizardStep>
      <WizardStep onSubmit={() => {
          console.log(wizardState);
          console.log("Step2 onSubmit");
        }}>
        <div>{wizardState.firstName}</div>
      </WizardStep>
    </Wizard>
  )
}

这是一个完整的代码沙盒示例：https://codesandbox.io/s/funny-galois-8xxwd?file=/src/App.js