Yup

安裝Yup

npm install yup

使用Yup

• 定義一個validationSchema,然後交給Formik來執行

import React from 'react';
import {TextInput, Button} from 'react-native';
import {Formik} from 'formik';
import * as Yup from 'yup';

const validationSchema = Yup.object().shape({
	email: Yup.string().required().email().label("Eamil"),
	password: Yup.string().required().min(4).label("Password")
});

const MyScreen = () => {
  return (
    <View>
      <Formik 
        initialValues={{email:'', password:''}}
    	onSubmit={(values) => console.log(values)}
        validationSchema={validationSchema}
      >
      {({handleChange, handleSubmit, errors}) => (
        <>
    	<TextInput onChangeText={handleChange('email')}>
        <Text style={{color:'red'}}>{errors.email}</Text>
    	<TextInput onChangeText={handleChange('password')}>
        <Text style={{color:'red'}}>{errors.password}</Text>
    	<Button onPress={handleSubmit}>
    	</>
      )}
	  
      </Formik>
    </View>
  );
}

export default MyScreen;