react-native-validate-form

A simple form validation for React Native

Getting Started

NPM

Install react-native-validate-form using NPM with:

npm install --save react-native-validate-form

Import

import { Form, Field } from 'react-native-validate-form';

Usage

See github documentation for more info.

import React from 'react';
import { View, Text } from 'react-native';
import { Form, Field } from 'react-native-validate-form';

import InputField from './InputField';

const required = value => (value ? undefined : 'This is a required field.');
const email = value => value && !/^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,5}$/i.test(value) ? 'Please provide a valid email address.' : undefined;

class MyForm extends React.Component {
  constructor() {
    super();

    this.state = {
      errors: [],
      email: ''
    }
  }
  submitForm() {
    let submitResults = this.myForm.validate();

    let errors = [];

    submitResults.forEach(item => {
      errors.push({ field: item.fieldName, error: item.error });
    });

    this.setState({ errors: errors });
  }

  render() {
    return(
      <Form
        ref={(ref) => this.myForm = ref}
        validate={true}
        submit={this.submitForm.bind(this)}
        errors={this.state.errors}
      >
        <Field
          required
          component={InputField}
          validations={[ required, email ]}
          name="email"
          value={this.state.email}
          onChangeText={(val) => this.setState({ email: val })}
          customStyle={{ width: 100 }}
        />
      </Form>
    );
  }
}

• InputField will represent your input field component, this component will receive the errors that will be thrown by this.myForm.validate().

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

  const InputField = ({
    name,           // field name - required
    customStyle,
    onChangeText,   // event
    value,          // field value
    disabled,
    placeholder,
    errors,         // this array prop is automatically passed down to this component from <Form />
  }) => {
    return (
      <View>
        <TextInput
          value={value && value}
          onChangeText={onChangeText ? (val) => onChangeText(val) : null}
          placeholder={placeholder ? placeholder : ""}
          disabled={disabled}
          style={customStyle ? customStyle : {}}
        />

        { errors && errors.length > 0 && errors.map((item, index) =>
            item.field === name && item.error ?
              <Text style={{ color: 'red' }}>
                {item.error}
              </Text>
            : <View />
          )
        }
      </View>
    );
  }

  export default InputField;

• If you have nested <Field /> components, you need to explicitly pass down errors as props so you can display the errors accordingly.
• There's no need to pass down errors as props if your <Field /> component is a direct child of <Form />.

  // ...
    <Form
      ref={(ref) => this.myForm = ref}
      validate={true}
      submit={this.submitForm.bind(this)}
      errors={this.state.errors} // you still need to pass errors as props to Form
    >
      <Field
        required
        component={InputField}
        validations={[ required, email ]}
        name="email"
        value={this.state.email}
        onChangeText={(val) => this.setState({ email: val })}
        customStyle={{ width: 100 }}
        // no need to pass down errors as props if <Field /> is a direct child of <Form />
      />
      <View>
        <Field
          required
          component={InputField}
          validations={[ required, email ]}
          name="email"
          value={this.state.email}
          onChangeText={(val) => this.setState({ email: val })}
          customStyle={{ width: 100 }}
          errors={this.state.errors} // explicitly pass down errors as props if your <Field /> is inside an element
        />
      </View>
    </Form>
  // ...

TODO: make an example in the repo for better documentation

Options

You can pass these props to the Form and Field components:

<Form
  ref={(ref) => this.myForm = ref}
  validate={true}
  submit={onSubmit}
>
  <Field
    required
    component={InputField}
    validations={[ sampleValidation() ]}
  />
</Form>

Props you can pass for the <Form /> component

Name	Type	Default	Required	Description
ref	string	null	yes	reference name
validate	boolean	false	no	set this to true to enable validation
submit	function	() => null	no	function callback if form is valid
failed	function	() => null	no	function callback if form is invalid
errors	array	[]	no	array that contains all your field errors and messages
style	object	{}	no	style object

Props you can pass for the <Field /> component

Name	Type	Default	Required	Description
required	boolean	false	no	set this to true to require the field
component	component / func	null	yes	input component or any component that needs validation
validateFieldName	string	'value'	no	name of the prop that will be validated
validations	func / array	[]	no	function or array of functions that contains your validation
customStyle	object	{}	no	style object

Credits

Jefferson Aux

License

The MIT License

Copyright (c) 2018 Jefferson Aux