reducer.plugin(Object<String, Function>)

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Returns a form reducer that will also pass each action through additional reducers specified. The parameter should be an object mapping from formName to a (state, action) => nextState reducer. The state passed to each reducer will only be the slice that pertains to that form.

Explanation

Part of the beauty of the flux architecture is that all the reducers (or "stores", in canonical Flux terminology) receive all the actions, and they can modify their data based on any of them. For example, say you have a login form, and when your login submission fails, you want to clear out the password field. Your login submission is part of another reducer/actions system, but your form can still respond.

Rather than just using the vanilla reducer from redux-form, you can augment it to do other things by calling the plugin() function.

Note: This is an advanced operation that allows you to modify the internal state of the redux-form state slice. You can mess things up if you are not careful.

Example

The example below will clear the login form's password field when the AUTH_LOGIN_FAIL action is dispatched.

import { createStore, combineReducers } from 'redux'
import { reducer as formReducer } from 'redux-form'
import { AUTH_LOGIN_FAIL } from '../actions/actionTypes'

const reducers = {
  // ... your other reducers here ...
  form: formReducer.plugin({
    login: (state, action) => {   // <----- 'login' is name of form given to reduxForm()
      switch(action.type) {
        case AUTH_LOGIN_FAIL:
          return {
            ...state,
            values: {
              ...state.values,
              password: undefined // <----- clear password value
            },
            fields: {
              ...state.fields,
              password: undefined // <----- clear field state, too (touched, etc.)
            }
          }
        default:
          return state
      }
    }
  })
}
const reducer = combineReducers(reducers)
const store = createStore(reducer)