using Material-ui checkboxes with the reactjs and redux

Modifying the answer by @BravoZulu by adding the event as the argument in onChange() function.(Also note that use onChange() instead of onCheck() for material-UI checkboxes as shown in the official documentation). Also, don't forget to bind the function in the constructor. I hope this helps the community. Below is the code.

    class App extends Component {
    constructor(props) {
        this.handleCheck = this.handleCheck.bind(this);
        super(props);
        this.state = {
        data: [apple, kiwi, banana, lime, orange, grape],
        checkedValues: []
        }
    }
    handleCheck(e,x) {
        this.setState(state => ({
        checkedValues: state.checkedValues.includes(x)
            ? state.checkedValues.filter(c => c !== x)
            : [...state.checkedValues, x]
        }));
    }

    render() {
        return (<div>
        { this.state.data.map(x =>
            <Checkbox
            label={x} key={x.toString()}
            onChange={e => this.handleCheck(e,x)}
            checked={this.state.checkedValues.includes(x)}
            />
        )}}
        </div>)
    }
}

In the handleCheck function, you are attempting to update your component state incorrectly. You need to use setState to make changes to state. In your example, state isn't getting updated so that is probably why you aren't seeing anything get selected. Also, gonna help clean up your example a bit:

class CheckboxList extends React.Component{
  constructor() {
    super();
    this.state = {
        data: ['apple', 'kiwi', 'banana', 'lime', 'orange', 'grape'],
      checkedValues: []
    }
  }
  handleCheck(index) {
    this.setState({
        checkedValues: this.state.checkedValues.concat([index])
    });
    console.log(this.state.checkedValues.concat([index]))
  }
  render(){
   const checks = this.state.data.map( (item, index) => {
         return (
         <span key={item}>
            <input type="checkbox"
           value={item}
           onChange={this.handleCheck.bind(this, index)} //Use .bind to pass params to functions
           checked={this.state.checkedValues.some( selected_index => index === selected_index )}
          />
          <label>{item}</label>
         </span>)
   });
   return <div>{checks}</div>
  }
}

Update: Added working jsfiddle.

A bit late to the party but here's a solution using a functional component and hooks

import React, { useState } from 'react';
import Checkbox from '@material-ui/core/Checkbox';

const App = ({ data }) => {
  const [checked, setChecked] = useState([]);

  const handleCheck = (event) => {
    const { value } = event.target;
    setChecked(checked.includes(value) ? checked.filter(c => c !== value) : [...checked, value]);
  };

  return (
    <div>
      {data.map(({ value }) => (
         <Checkbox onChange={e => handleCheck(e)} checked {checked.includes(value)} />
      ))}
   </div>
  );
};

export default App;

In React, you shouldn't push data directly to your state. Instead, use the setState function.

class App extends Component {
  constructor(props) {
    super(props);
    this.state = {
      data: [apple, kiwi, banana, lime, orange, grape],
      checkedValues: []
    }
  }
  handleCheck(x) {
    this.setState(state => ({
      checkedValues: state.checkedValues.includes(x)
        ? state.checkedValues.filter(c => c !== x)
        : [...state.checkedValues, x]
    }));
  }

  render() {
    return (<div>
    { this.state.data.map(x =>
        <Checkbox
          label={x} key={x.toString()}
          onCheck={() => this.handleCheck(x)}
          checked={this.state.checkedValues.includes(x)}
         />
    )}}
    </div>)
  }
}

I was also stuck on this issue for quite some time when I finally found a fix to this. It never works for a functional component which returns a check box. I made a separate class component and wrapped it in Redux Field component and it worked perfectly. I really never understood why it didn't work for the fucntional component as it what is shown in their official example.

I have written the code that worked for me. Hope it helps :)

class CheckBoxInput extends React.Component {

  onCheckBoxSelectChange = (input) => 
  {
    input.onChange();
    this.props.onSelectChange();
  }

  render() {
    const { label, input,} = this.props;
    let name = input.name;

    return (
      <div>
        <InputLabel htmlFor={label} style={{paddingTop: '15px'}}> {label} </InputLabel>
         <FormControl {...input} >
          <Checkbox
            name = {name}
            label = {label}
            color= "primary"
            checked={input.value ? true : false}
            onChange={() => this.onCheckBoxSelectChange(input)}
          />          
        </FormControl>
      </div>

    )
  }
}

const CheckBox = (props) => <Field component={CheckBoxInput} {...props} />;
export default CheckBox;

And to use this checkbox component:

 <CheckBox  name="isCurrent" label="Current" onSelectChange = {this.toggleCurrentEmployerSelection} />

In case you are working with objects instead of simple data types, here is a working approache:

class App extends Component {
  constructor(props) {
    super(props);
    this.state = {
      data: [{id: 1, name:'banana'},
             {id: 2, name:'kiwi'}],
      checkedValues: []
    }
  }
  handleCheck(element) {
     const values = this.state.checkedValues.filter(e => e.id === element.id).length > 0
            ? this.state.checkedValues.splice( this.state.checkedValues.findIndex( e => e.id === element.id),1)
            : this.state.checkedValues.push(element);
     this.setState({
         checkedValues: values
     });
  }

  render() {
    return (<div>
    { this.state.data.map(el =>
        <Checkbox
           checked={this.state.checkedValues.filter(e => e.id === el.id).length > 0}
           onChange={this.handleCheck.bind(this, el)} //Use .bind to pass params to functions
           value={el}
        />
    )}}
    </div>)
  }
}

So basically what the function handleCheck does is it checks whether the selected object is in the checkedValues array, if that is the case then it deletes it (case uncheck), otherwise it adds it (case check), is i add the checked object to the checkedValues array.

in the Checkbox checked checks whether there is an object in the checkedValues array that is equal to the current loop object, (case checked/unchecked)