react-native-use-on-change

Hook provides easy functionality to validate and handle forms. Don't duplicate your code! Just use this hook to build all your validation.

Installation

expo: expo install react-native-use-on-change
npm: npm i react-native-use-on-change
yarn: yarn add react-native-use-on-change

Basic usage

Input.jsx

import {TextInput, View} from "react-native";
import React from "react";


export default function Input({name, error, onChange, value}) {
    let errorToShow = error?.[name];

    const handleChange = text => onChange({name, value: text});

    return(
        <View
            style={{
                height: 60,
                marginVertical: 5,
                backgroundColor: 'gray',
                width: '100%'
            }}
        >
            <TextInput style={{flex: 1,}} value={value?.[name]} onChangeText={handleChange}/>
        </View>
    )
}

import useOnChange from "react-native-use-on-change";

export default function YourComponent() {
// You can use many things from hook and define names you want. 
// 1. data is basicaly your data Object with key:value for each field.
// 2. onChange function which should be passed to inputs to handle their state.
   const [data, onChange] = useOnChange({
        initialState: {
            field1: '',
            field2: '',
        },
    });

   return(
       <View
            style={{
                flex: 0.7
            }}
        >
            <View
                style={{
                    flex: 0.5,
                    justifyContent: 'center',
                    overflow: 'hidden'
                }}
            >
                <Input name={'field1'} value={data} onChange={onChange}/>
                <Input name={'field2'} value={data} onChange={onChange}/>                    
            </View>               
        </View>
   )
}

// more about customizing below

Advanced usage

In case you want to use this hook you should prepare any form components to use onChange, value, errors, name. Remember they required to use this hook!

For example: Input.jsx

import {TextInput, View} from "react-native";
import React from "react";


export default function Input({name, error, onChange, value}) {
    let errorToShow = error?.[name];

    const handleChange = text => onChange({name, value: text});

    return(
        <View
            style={{
                height: 60,
                marginVertical: 5,
                backgroundColor: 'gray',
                width: '100%'
            }}
        >
            <TextInput style={{flex: 1,}} value={value?.[name]} onChangeText={handleChange}/>
        </View>
    )
}

Then we use our prepared input somewhere in our app with useOnChange hook. And that's all.

// Custom validator
const customValidator = (paramToCheck, message) => (value) => value === paramToCheck ? '' : message;

export default function Container() {
   const [otherValue, setOtherValue] = useState(false);
   // You can use many things from hook and define names you want. 
   // 1. data is basicaly your data Object with key:value for each field.
   // 2. onChange function which should be passed to inputs to handle their state.
   // 3. errors created by validation functions.
   // 4. canSave property which shows to us when all fields is filled and passed validation.
   // 5. requestFunction is function you want to use to save validated data.
   // 6. loading based or requestFunction state you can show users when you process their data.
    const [data, onChange, errors, canSave, save, saving] = useOnChange({
        // Initial state
        initialState: {
            field1: '',
            field2: '',
            // Field 3 is not required
            field3: '',
        },
        // Validators with validate functions for each field
        validators: {
            field1: [
                isRequired('This field is required'),
                minLength(5, 'Min value is 5'),
                maxLength(255, 'Max is 255'),
            ],
            field2: [
                isRequired('This field is required'),
                minLength(5, 'Min value is 5'),         
                maxLength(255, 'Max is 255'),
                // We added our custom validator
                customValidator('Sample string', 'Value should be sample string')
            ],
            // If we want validation to skip field3 we just do not list it here
        },
        config: {
            // Method for saving
            fetchMethod: async (data) => {
                // Save data somewhere
            }
        },
        canSaveConfig: {
            // For example if we have edit flow, when button should toggle when data in form has changed
            cantSaveUnchanged: true,
            // Custom validation checker
            validationFunction: (data, errors, state) => {
                // Some of your custom validation code it should return boolean
            }
        }
        // Deeps to reset hook
    }, [otherValue]);

    return (
        <View
            style={{
                flex: 1,
                justifyContent: 'center',
                alignItems: 'center'
            }}
        >
            <Input name={'field1'} value={data} onChange={onChange} error={errors}/>
            <Input name={'field2'} value={data} onChange={onChange} error={errors}/>
            <TouchableOpacity
                disabled={!canSave}
                style={[{
                    flexDirection: 'row',
                    height: 60,
                    width: '100%',
                    backgroundColor: 'green',
                    justifyContent: 'center',
                    alignItems: 'center',
                }, !canSave && {
                    backgroundColor: 'red',
                }]}
                onPress={save}
            >
                <Text>
                    Save
                </Text>
            </TouchableOpacity>
            <TouchableOpacity
                style={[{
                    flexDirection: 'row',
                    height: 60,
                    width: '100%',
                    backgroundColor: 'blue',
                    justifyContent: 'center',
                    alignItems: 'center',
                }]}
                onPress={() => setOtherValue(!otherValue)}
            >
                <Text>
                    Reset hook
                </Text>
            </TouchableOpacity>
        </View>
    )
}
// more about customizing below

Validators

Name	Params	Params
minLength(8, 'Your min message')	(number, string)	Number of min characters and message to show when validation fails
maxLength(8, 'Your max message')	(number, string)	Number of max characters and message to show when validation fails
isRequired('Your message')	(string)	Required field validation
isValueEqual('field_name', 'Your message')	(string, string)	Take field name to check if value equal to this field value
isPhoneValid('Your message')	(string)	Validate phone number field
isEmailValid('Your message')	(string)	Validate your email field
isValidHex('Your message')	(string)	Hex validation