How to send data from dialog back to parent container with react?

Don't save events in your state in Popup access the events directly from props.

In your Calendar, create a function that'll update the state.

updateEvents = (events, callback = () => {}) => {
  this.setState(
    {
      events
    },
    callback
  );
};

<Popup updateEvents={this.updateEvents} ref={this.ModalAjoutb} id_user={this.state.id_user} events={this.state.events} />

Popup

export default class Popup extends Component {
  constructor(props) {
    super(props);
  }

  handleAjouterb = id_user => {
    this.setState(
      {
        openPopupAjout: true,
        id_user
      },
      () => {
        this.fetchingPopup(
          this.state.id_user,
          this.state.identifiant_user,
          this.state.nom_user
        );
      }
    );
  };
  fetchingPopup = (id_user, identifiant_user, nom_user) => {
    const praticiensCached = JSON.parse(
      localStorage.getItem('Liste de praticiens ')
    );
    for (let j = 0; j < praticiensCached.length; j++) {
      if (id_user === praticiensCached[j].id_user) {
        identifiant_user = praticiensCached[j].identifiant_user;
        this.setState({ nom_user: praticiensCached[j].nom_user });
      }
    }
    handleValider = event => {
      event.preventDefault();
      const praticiensCached = JSON.parse(
        localStorage.getItem('Liste de praticiens ')
      );
      for (let j = 0; j < praticiensCached.length; j++) {
        if (this.state.id_user === praticiensCached[j].id_user)
          this.state.identifiant_user = praticiensCached[j].identifiant_user;
      }

      const formData = new FormData();

      formData.append('identifiant_user', this.state.identifiant_user);
      formData.append('heuredebut', this.state.tranchesC[0].startC);
      formData.append('heurefin', this.state.tranchesC[0].endC);
      formData.append('libelleconge', this.state.libelle);
      axios({
        method: 'post',
        url: process.env.REACT_APP_API_BACKEND + 'add_event_docteur',
        data: formData,
        headers: {
          'Content-Type': 'application/json',
          Accept: 'application/json'
        }
      }).then(() => {
        fetch(
          process.env.REACT_APP_API_BACKEND +
            'get_liste_planning/start=' +
            moment()
              .startOf('isoweek')
              .subtract(14, 'days')
              .toJSON() +
            '&end=' +
            moment()
              .endOf('isoweek')
              .add(2, 'months')
              .toJSON() +
            '&identifiant_user=' +
            this.state.identifiant_user
        )
          .then(Response => Response.json())
          .then(data => {
            let evts = data.ListeResult;
            for (let i = 0; i < evts.length; i++) {
              evts[i].start = moment(evts[i].start).toDate();
              evts[i].end = moment(evts[i].end).toDate();
            }
            this.props.updateEvents(evts, () => {
              localStorage.setItem(
                'Liste récente de planning de ' + this.state.nom_user,
                JSON.stringify(evts)
              );
              localStorage.removeItem(
                'Liste de planning de ' + this.state.nom_user
              );
              localStorage.setItem(
                'Liste de planning de ' + this.state.nom_user,
                JSON.stringify(evts)
              );
            });
          });
      });
    };
  };

  render() {
    return (
      <div>
        <Dialog
          icon="application"
          onClose={this.handleClose}
          title="Organisation des plannings du docteur"
          {...this.state}
          isOpen={this.state.openPopupAjout}
        >
          <Input
            id="libelle"
            style={{ width: '480px' }}
            value={this.state.libelle}
            onChange={this.handleInputChange('libelle')}
          />
          <label className="pt-label .modifier">
            <strong>Date</strong>
          </label>
          <LocaleProvider locale={fr_FR}>
            <RangePicker
              id="date"
              name="date"
              locale="fr"
              placeholder={['Date de début', 'Date de fin']}
              separator="-"
              onChange={this.handleDateCChange}
              value={this.state.dateIC}
              format="DD/MM/YYYY"
              allowClear={false}
            />
          </LocaleProvider>
          <label className="pt-label .modifier">
            {' '}
            <strong>Heure de début</strong>
          </label>
          <Time
            value={el.startC}
            onChange={time => this.handleKeyboardStartCChange(i, time)}
            style={heure}
            disableUnderline={true}
            inputComponent={TextMaskCustom}
            endAdornment={
              <InputAdornment position="end" style={{ opacity: '0.4' }}>
                {' '}
                <IconButton
                  onClick={() => this.openDialogC(i, el.startC, 'startC')}
                >
                  <i style={{ fontSize: '18px' }} className="zmdi zmdi-alarm" />
                </IconButton>{' '}
              </InputAdornment>
            }
          />
          <label className="pt-label .modifier">
            {' '}
            <strong>Heure de fin</strong>
          </label>
          <Time
            value={el.endC}
            onChange={time => this.handleKeyboardEndCChange(i, time)}
            style={heure}
            disableUnderline={true}
            inputComponent={TextMaskCustom}
            endAdornment={
              <InputAdornment position="end" style={{ opacity: '0.4' }}>
                {' '}
                <IconButton
                  onClick={() => this.openDialogC(i, el.endC, 'endC')}
                >
                  <i style={{ fontSize: '18px' }} className="zmdi zmdi-alarm" />
                </IconButton>
              </InputAdornment>
            }
          />
          <Clock
            maxWidth="xs"
            open={this.state.isOpenC}
            onBackdropClick={this.closeDialogC}
          >
            <TimePicker
              mode="24h"
              value={this.createDateFromTextValueC(this.state.datePickerValueC)}
              onChange={this.handleDialogCChange}
            />
            <DialogActions>
              {' '}
              <ButtonOk onClick={this.closeDialogC} color="primary">
                {' '}
                Ok{' '}
              </ButtonOk>
            </DialogActions>
          </Clock>
          <AnchorButton
            style={{ display: 'inline-block' }}
            intent={Intent.SUCCESS}
            onClick={this.handleValider}
          >
            Valider
          </AnchorButton>
      </div>
    );
  }
}

I think, you can achieve it using code like this:

export default ComponentA extends Component {
  // set localStorage to bar state value
  // via click or whatever ...
    foo () {
    this.setState({
      bar: localStorage.getItem('bar')
    })
  }

  render () {
    // send the value of state to ComponentB
    return <ComponentB foo={this.state.bar}>
  }
}

Into your component

export default class ComponentB extends Component {
    render () {
    // display the value of foo prop
    return <div>{this.props.foo}</div>
  }
}

Note: You can always try to get the content of your localStoragedirectly from the ComponentB(Maybe using ComponentDidUpdate???) but the way I show you is better.

Why not you use context Feature of React React Context API

context.js

export const store = {
  something: 'val',
  setSomeThing : () => {}
};

export const CalContext = React.createContext(
  store // default value
);

pop-up.js

import {CalContext} from './context';

class Popup extends React.Component {

   updateValue = () => {
     this.context.setSomeThing('new_value');
   }    

   render() {
    let calContext = this.context;

    return (
      <button onClick={this.updateValue} >
        {calContext.something}
      </button>
    );
  }
}

Popup.contextType = CalContext;

export default Popup;

calender.js

import {CalContext} from './context';
import Popup from './pop-up'

class calender extends React.Component {
   constructor(props) {
      this.state = {
         something : 'value'
      }
   }

  setSomeThing = (newVal) => {
    // actual set something code.
    this.setState({something : newVal});
  }

render() {
let contextVal = { something : this.state.something, setSomeThing : this.setSomeThing }
// The entire state is passed to the provider
return (
  <CalContext.Provider value={contextVal}>
    <Popup />
  </CalContext.Provider>
   );}
}

Are you looking for something like this

class ComponentB extends React.Component{
  render(){
    this.props.setInLocalStorage();
    const value = localStorage.getItem("testA");
    return <div>
  This is componentB{value}
  </div>}
}
class ComponentA extends React.Component{
 setInLocalStorage = ()=>{
   localStorage.setItem('testA', 'Hello');
}
render(){
  return <ComponentB setInLocalStorage={this.setInLocalStorage}/>
}
}

You can either use React Context API or Redux.

But if you don't want those, you can use a prop that is a method in your child component, so the parent can capture the event. It is similar Output mechanic from Angular 2+.

Here is an example:

const ChildComponent = (onSelect = () => {}) => {
  return <div onClick={() => onSelect('You selected me')}>Child Component</div>
}

const ParentComponent = () => {
  return <ChildComponent onSelect={message => console.log(message)} /> // You selected me
}

In your parent component i.e <Calendar/> you can a define a method for say

HandleNewDataFromPopup(data) {
   this.setState({newData: data})
}

and pass this method as a prop in the Popup component

<Popup HandleNewDataFromPopup={this.HandleNewDataFromPopup}/>

and in your <Popup/> component in the method handleValider on sucess of fetch call you can call the method HandleNewDataFromPopup (this.props.HandleNewDataFromPopup) to populate the data in your parent component

handleValider() {
  // on axios success
  this.props.HandleNewDataFromPopup(data)
}

Does this answer your question?