Can I mapDispatchToProps without mapStateToProps in Redux?

Question

I am breaking apart Redux' todo example to try to understand it. I read that mapDispatchToProps allows you to map dispatch actions as props, so I thought of rewriting addTodo.js to use mapDispatchToProps instead of calling dispatch(addTodo()). I called it addingTodo(). Something like this:

import React from 'react'; import {connect} from 'react-redux'; import addTodo from '../actions';  let AddTodo = ({addingTodo}) => {   let input;   return (       <div>         <form onSubmit={e => {           e.preventDefault()           if (!input.value.trim()) {             return           }           addingTodo(input.value)           input.value = ""         }}>           <input ref={node => {             input = node           }} />           <button type="submit">Submit</button>         </form>       </div>   ) }  const mapDispatchToProps = {   addingTodo: addTodo }  AddTodo = connect(   mapDispatchToProps )(AddTodo)  export default AddTodo 

However, when I run the app, I get this error: Error: Invalid value of type object for mapStateToProps argument when connecting component AddTodo.. I never used mapStateToProps to begin with on AddTodo component, so I was not sure what was wrong. My gut feeling says that connect() expects mapStateToProps to precede mapDispatchToProps.

The working original looks like this:

import React from 'react'; import {connect} from 'react-redux'; import addTodo from '../actions';  let AddTodo = ({dispatch}) => {   let input;   return (       <div>         <form onSubmit={e => {           e.preventDefault()           if (!input.value.trim()) {             return           }           dispatch(addTodo(input.value))           input.value = ""         }}>           <input ref={node => {             input = node           }} />           <button type="submit">Submit</button>         </form>       </div>   ) }  AddTodo = connect()(AddTodo)  export default AddTodo 

Complete repo can be found here.

So my question is, is it possible to do mapDispatchToProps without mapStateToProps? Is what I am trying to do an acceptable practice - if not, why not?

Answer 1

Yes, you can. Just pass null as first argument:

AddTodo = connect(     null,     mapDispatchToProps )(AddTodo) 

Yes, it's not just acceptable practice, it's recommended way to trigger actions. Using mapDispatchToProps allows to hide the fact of using redux inside your react components