React Native Formik

Forms are very verbose in React, and a lot of the time, you end up copy pasting a lot of boilerplate.

This repository is a set of high order components designed to help you take control again of your forms with React Native and Formik

Features

Easily composable set of helpers
Connects your React Native input to Formik with no boilerplate (See makeReactNativeField)
Add a type prop on your TextInput to take care of the input options based on the type (See withInputTypeProps)
Automatically focus the next input (See withNextInputAutoFocus)

Table of contents

Installation
Advanced Example
Formatting inputs
API

Installation

yarn add formik react-native-formik

Advanced Example

Say we want to create a form with Material design inputs.

Create a custom input

Let's create our custom text input design, called MaterialTextInput:

We can use react-native-material-textfield for the material design.

Our component takes error and touched in addition to the usual TextInput props. Notice our component also implement a focus function, for withNextInputAutoFocus to work.

// MaterialTextInput.js
import React from 'react';
import { Text, View } from 'react-native';
import { TextField } from 'react-native-material-textfield';

export default class MaterialTextInput extends React.PureComponent {
  // Your custom input needs a focus function for `withNextInputAutoFocus` to work
  focus() {
    this.input.focus();
  }

  render() {
    const { error, touched, ...props } = this.props;

    const displayError = !!error && touched;
    const errorColor = 'rgb(239, 51, 64)';

    return (
      <View>
        <TextField
          ref={input => (this.input = input)}
          labelHeight={12}
          baseColor={displayError ? errorColor : '#1976D2'}
          tintColor="#2196F3"
          textColor="#212121"
          {...props}
        />
        <Text
          style={{
            textAlign: 'right',
            color: displayError ? errorColor : 'transparent',
            height: 20,
          }}
        >
          {error}
        </Text>
      </View>
    );
  }
}

Create our form logic

Compose our input with high order components to make it awesome. react-native-formik exports as default compose(withInputTypeProps, setFormikInitialValue, withError, withTouched, makeReactNativeField);.

Let's add in withNextInputAutoFocusInput:

import { compose } from 'recompose';
import makeInputGreatAgain, { withNextInputAutoFocusInput } from 'react-native-formik';
import MaterialTextInput from './MaterialTextInput';

const MyInput = compose(makeInputGreatAgain, withNextInputAutoFocusInput)(MaterialTextInput);

To complement withNextInputAutoFocusInput, we need to create a Form component, for instance:

import { View } from 'react-native';
import { withNextInputAutoFocusForm } from 'react-native-formik';

const Form = withNextInputAutoFocusForm(View);

We can also create a validation schema, with yup. It's of course possible to use other validation possibilities provided by Formik, but yup makes validation and error messaging painless.

import Yup from 'yup';

const validationSchema = Yup.object().shape({
  email: Yup.string()
    .required()
    .email("well that's not an email"),
  password: Yup.string()
    .required()
    .min(2, 'pretty sure this will be hacked'),
});

Then the form in itself becomes simple:

export default props => (
  <Formik
    onSubmit={values => console.log(values)}
    validationSchema={validationSchema}
    render={props => {
      return (
        <Form>
          <MyInput label="Email" name="email" type="email" />
          <MyInput label="Password" name="password" type="password" />
          <MyInput label="First Name" name="firstName" type="name" />
          <MyInput label="Last Name" name="lastName" type="name" />
          <Button onPress={props.handleSubmit} title="SUBMIT" />
        </Form>
      );
    }}
  />
);

Full code:

import React from 'react';
import { Button, TextInput, View } from 'react-native';
import { compose } from 'recompose';
import { Formik } from 'formik';
import Yup from 'yup';
import makeInputGreatAgain, {
  withNextInputAutoFocusForm,
  withNextInputAutoFocusInput,
} from 'react-native-formik';
import MaterialTextInput from './MaterialTextInput';

const MyInput = compose(makeInputGreatAgain, withNextInputAutoFocusInput)(MaterialTextInput);
const Form = withNextInputAutoFocusForm(View);

const validationSchema = Yup.object().shape({
  email: Yup.string()
    .required('please! email?')
    .email("well that's not an email"),
  password: Yup.string()
    .required()
    .min(2, 'pretty sure this will be hacked'),
});

export default props => (
  <Formik
    onSubmit={values => console.log(values)}
    validationSchema={validationSchema}
    render={props => {
      return (
        <Form>
          <MyInput label="Email" name="email" type="email" />
          <MyInput label="Password" name="password" type="password" />
          <MyInput label="First Name" name="firstName" type="name" />
          <MyInput label="Last Name" name="lastName" type="name" />
          <Button onPress={props.handleSubmit} title="SUBMIT" />
        </Form>
      );
    }}
  />
);

Formatting inputs

You may need to format inputs as the user types in. For instance, adding spaces in a telephone number (0612345678 -> 06 12 34 56 78).
Here's how you would do it:

const formatPhoneNumber: string => string = (unformattedPhoneNumber) => ...;

...

<Formik
    render={({ values }) => {
      return (
        <Form>
          <MyInput name="phoneNumber" value={formatPhoneNumber(values.phoneNumber)} />
        </Form>
      );
    }}
/>

API

makeReactNativeField

Connects your React Native component to the Formik context:

its value will be set
it will send onChangeText and onBlur events to Formik

Now you only need this code:

import React from 'react';
import { TextInput, View } from 'react-native';
import { Formik } from 'formik';
import { makeReactNativeField } from 'react-native-formik';

const MyInput = makeReactNativeField(TextInput);

export default props => {
  return (
    <Formik
      onSubmit={values => console.log(values)}
      render={props => {
        return (
          <View>
            <MyInput name="email" />
            <MyInput name="password" />
          </View>
        );
      }}
    />
  );
};

instead of:

import React from 'react';
import { TextInput, View } from 'react-native';
import { Formik } from 'formik';
import { makeReactNativeField } from 'react-native-formik';

const MyInput = makeReactNativeField(TextInput);

export default props => {
  return (
    <Formik
      onSubmit={values => console.log(values)}
      render={props => {
        return (
          <View>
            <MyInput
              name="email"
              value={props.value.email}
              onChangeText={text => props.setFieldValue('email', text)}
              onBlur={() => setFieldTouched('email')}
            />
            <MyInput
              name="password"
              value={props.value.email}
              onChangeText={text => props.setFieldValue('password', text)}
              onBlur={() => setFieldTouched('password')}
            />
          </View>
        );
      }}
    />
  );
};

setFormikInitialValue

Set Input initial value to "" to Formik without having to use initialValues prop.

Especially it allows validation of untouched inputs when pressing submit.

withError

Pass in the Formik error for the input as a prop.

withFocus

Add a focused prop to the input depending on its focus state.

withFormik

Pass Formik context as a prop to any component.

withInputTypeProps

Let's face it, you'll always want to remove auto-capitalization for email inputs and use the email keyboard.

Using withInputTypeProps and passing a type, you'll always get the correct props for you input.

import { TextInput } from 'react-native';
import { withInputTypeProps } from 'react-native-formik';

const MyInput = withInputTypeProps(TextInput);

const emailInput = () => <MyInput type="email" />;

Authorized types as of now are email, password, digits and name. Setting another type has no consequence.

Check the props set by the type in the source!

withNextInputAutoFocus

when an input is submitted, it will automatically focuses on the next or submit the form if it's the last one
sets return key to "next" or "done" if input is the last one or not
⚠️ your input component needs to be a class and needs to implement a focus function
⚠️ Inputs need to be wrapped by withNextInputAutoFocusInput and the container of the inputs need to be wrapped in withNextInputAutoFocusForm.

import { TextInput, View } from 'react-native';
import { withNextInputAutoFocusForm, withNextInputAutoFocusInput } from 'react-native-formik';

const MyInput = withNextInputAutoFocusInput(TextInput);
const Form = withNextInputAutoFocusForm(View);

export default props => (
  <Formik
    onSubmit={values => console.log(values)}
    validationSchema={validationSchema}
    render={props => {
      return (
        <Form>
          <MyInput label="Email" name="email" type="email" />
          <MyInput label="Password" name="password" type="password" />
          <MyInput label="First Name" name="firstName" type="name" />
        </Form>
      );
    }}
  />
);

withTouched

Pass in the Formik touched value for the input as a prop.

withPickerValues

Wraps your component into a TouchableOpacity which, when pressed, opens a dialog to pick a value. You need to provide a values props with the pickable items.

If you need to dismiss the picker's "Keyboard", you can use KeyboardModal.dismiss() like below.

import { TextInput, View } from 'react-native';
import { compose } from "recompose";
import makeInput, { KeyboardModal, withPickerValues } from 'react-native-formik';

const MyPicker = compose(makeInput, withPickerValues)(TextInput);

export default props => (
  <Formik
    onSubmit={values => { KeyboardModal.dismiss(); console.log(values); }}
    validationSchema={validationSchema}
    render={props => {
      return (
        <View>
          <MyPicker
            name="gender"
            values={[{ label: 'male', value: 'Mr' }, { label: 'female', value: 'Mrs' }]}
          />
        </View>
      );
    }}
  />
);

Guide

Move form above keyboard

The purpose of this section is to give you a solution to create a bottom form which will go up when the keyboard appears, and the content at the top at the page will disappear.

You have to:

Create a form like you learnt above ;
Use react-native-keyboard-spacer: it will create view with the keyboard's size when the keyboard will opened;
Use react-native-hide-with-keyboard: it will hide component when the keyboard will opened.

import React, { PureComponent } from "react";
import { Image, Platform, ScrollView } from "react-native";
import Hide from "react-native-hide-with-keyboard";
import KeyboardSpacer from "react-native-keyboard-spacer";
import { Formik } from "formik";
import { Button, FormFormik, TextInputFormik } from "./components";
const cat = require("./cat.jpg");

class AdoptACat extends PureComponent<{}> {
  render() {
    return (
      <ScrollView
        style={styles.container}
        contentContainerStyle={styles.contentContainer}
        keyboardShouldPersistTaps="handled"
      >
        <Hide>
          <Image source={cat} style={styles.image} />
        </Hide>
        <View style={styles.fillContainer} />
        <Formik
          onSubmit={() => {}}
          render={props => (
            <FormFormik>
              <TextInputFormik
                name="catName"
                placeholder={"His name"}
                returnKeyType="next"
                type="name"
              />
              <TextInputFormik
                name="humanName"
                placeholder={"Your name"}
                returnKeyType="done"
                type="name"
              />
              <Button text={"Adopt him ..."} />
            </FormFormik>
          )}
        />
        {Platform.OS === "ios" && <KeyboardSpacer />}
      </ScrollView>
    );
  }
}

const styles = {
  container: {
    backgroundColor: "white",
    flex: 1,
    padding: 20
  },
  contentContainer: {
    flex: 1
  },
  fillContainer: {
    flex: 1
  },
  image: {
    alignSelf: "center",
    resizeMode: "contain"
  }
};

export default AdoptACat;

For Android, we don't have to use react-native-keyboard-spacer because android:windowSoftInputMode is in adjustResize mode. Indeed, the view is automatically resize and you don't have to fill it like on iOS.

Enjoy your life :

Tketa/react-native-formik

README