Question

有没有一种方法可以将文本输入限制在最小长度和最大长度之间。假设我想将textinput的长度限制在5到15之间，该怎么做？

Answer 1

您可以按照以下步骤使用redux-form进行操作

we.js

module.exports = {

    reqMsg: 'Required',

    maxLength: max => value => value && value.length > max ? `Must be ${max} characters or less` : undefined,

    minValue: min => value => value && value.length < min ? `Must be at least ${min} characters` : undefined,
  };

validations.js

import { reqMsg, maxLength, minValue } from './we';
module.exports = {
    //Validation
    required: value => value ? undefined : reqMsg,

    maxLength15: maxLength(15),

    minValue5: minValue(5)
};

UserCreateForm.js

import React, { Component } from 'react';
import { Field, reduxForm } from 'redux-form';
import { Item, Input, CheckBox, ListItem, Spinner, Icon } from 'native-base';
import { required, minValue5, maxLength15} from './validations';


const renderField = ({ secureTextEntry, iconType, iconName, keyboardType, placeholder, meta: { touched, error, warning }, input: { onChange, ...restInput } }) => {
    return (
        <View>
            <Item error={touched && !!error} rounded>
                <Icon type={iconType} name={iconName} />
                <Input secureTpickerStyleextEntry={JSON.parse(secureTextEntry)} keyboardType={keyboardType}
                    onChangeText={onChange} {...restInput} placeholder={placeholder} autoCapitalize='none'>
                </Input>
                {touched && !!error && <Icon name='close-circle' />}
            </Item>
                {touched && (!!error && <Text>{error}</Text>)}
        </View>
    );
};

class UserComponent extends Component {

    render() {

        return (

                <Field name="Name" iconType="SimpleLineIcons" iconName="user" secureTextEntry="false" keyboardType="default" placeholder="FirstName LastName NikeName" component={renderField}
                    validate={[required, minValue5, maxLength15]}
                />
        );
    }
}

const UserCreateForm = reduxForm({
    form: USER_CREATE_FORM // a unique identifier for this form
})(UserComponent);

export default UserCreateForm;

Answer 2

考虑在您的组件中添加以下代码：

<TextInput onTextChange={this.onTextChange} maxLength={15} ... />
<Button onPress={this.onPress} ... >Submit</Button>

onTextChange = text => {
   this.setState({text : text});
}

onPress = () => {
   const {text} = this.state;

   if(text.length < 5) {
      console.log('Your text is less than what is required.');
   }
}

Answer 3

先前的评论也不错，但是它具有更多的时间和空间复杂性。为此，请使用此代码。

<TextInput onTextChange={this.onTextChange} maxLength={15} ... />

onTextChange=()=>{

 if (value ==^[a-zA-Z0-9]{5,15}$) {
        alert( "Input is valid\n");
    } else {
        alert( "Input is invalid\n");
    }
}

此代码可帮助我使用此代码，也可以重置限制长度，更改值这里5：-最小 15：-最大值。

文本输入的最小长度React本机

3 个答案: