Formik-Autosave

Formik-Autosave.jsx

import React from 'react';
import PropTypes from 'prop-types'
import debounce from 'lodash.debounce' // or whatevs
import isEqual from 'lodash.isEqual' 

class AutoSave extends React.Component {
    static contextTypes = {
      formik: PropTypes.object
    }

    state = {
       isSaving: false,
    }
    
    componentWillReceiveProps(nextProps, nextContext) {
       if (!isEqual(nextProps.values, this.props.values)) {
          this.save()
       }
    }
 
    save = debounce(() => {
      this.setState({ isSaving: true, saveError: undefined })
      this.props.onSave(this.props.values) 
        .then(
          () => this.setState({ isSaving: false, lastSaved: new Date() }),
          () => this.setState({ isSaving: false, saveError })
        )
      }), 300)
    }

    render() {
      return this.props.render(this.state)
   }
  }
}

// Usage
import React from 'react';
import { Formik, Field, Form } from 'formik'
import distanceInWordsToNow from 'date-fns/distance_in_words_to_now'


const App = () =>
  <div>
    <h1>Signup form</h1>  
    <Formik
      initialValues={{ firstName: '', lastName: ''}
      onSubmit={values => {
        setTimeout(() => {
          alert(JSON.stringify(values, null,2))
        }, 500)
      }
      render={() => 
       <Form>
        <Field name="firstName" />
        <Field name="lastName" />
        <button type="submit">Submit</button>
        <AutoSave
          onSave={values => CallMyApi(values) /* must return a promise 😎 */}\
          debounce={1000}
          render={({isSaving, lastSaved, saveError }) => 
            <div>
              {!!isSaving 
                ? <Spinner/>
                : !!saveError 
                  ? `Error: ${saveError}`
                  : lastSaved 
                    ? `Autosaved ${distanceInWordsToNow(lastSaved)} ago` 
                    : 'Changes not saved'}
            </div>
          }
         />
       </Form>
      }
    />
  </div>

There's one tiny problem with the solutions above - when you rely solely on formik.dirty, you will miss any changes that result in a field value equal to initialValues, as per specs:

dirty: boolean
Returns true if values are not deeply equal from initial values, false otherwise. dirty is a readonly computed property and should not be mutated directly.

So when your Formik doesn't have enableReinitialize prop enabled (by default, it doesn't) and you change some field, autosave submits your form, and then you change that field once more to value equal with initial value - it won't detect that as a change.

For most implementations, that may not be the case, or maybe you can use enableReinitialize - but I didn't want to, as users can lose the focused field when reinitialization happens. So I came up with another implementation, which holds the last submitted values in its state, and uses isEqual from react-fast-compare just as Formik internally does.

You can find this implementation here: https://gist.github.com/SPodjasek/c5354da2e897daa14654674ab21c9b72