How to update nested state properties in React

Question

I\'m trying to organize my state by using nested property like this:

this.state = {
   someProperty: {
      flag:true
   }
}

But updating

Answer 1

stateUpdate = () => {
    let obj = this.state;
    if(this.props.v12_data.values.email) {
      obj.obj_v12.Customer.EmailAddress = this.props.v12_data.values.email
    }
    this.setState(obj)
}

Answer 2

To make things generic, I worked on @ShubhamKhatri's and @Qwerty's answers.

state object

this.state = {
  name: '',
  grandParent: {
    parent1: {
      child: ''
    },
    parent2: {
      child: ''
    }
  }
};

input controls

<input
  value={this.state.name}
  onChange={this.updateState}
  type="text"
  name="name"
/>
<input
  value={this.state.grandParent.parent1.child}
  onChange={this.updateState}
  type="text"
  name="grandParent.parent1.child"
/>
<input
  value={this.state.grandParent.parent2.child}
  onChange={this.updateState}
  type="text"
  name="grandParent.parent2.child"
/>

updateState method

setState as @ShubhamKhatri's answer

updateState(event) {
  const path = event.target.name.split('.');
  const depth = path.length;
  const oldstate = this.state;
  const newstate = { ...oldstate };
  let newStateLevel = newstate;
  let oldStateLevel = oldstate;

  for (let i = 0; i < depth; i += 1) {
    if (i === depth - 1) {
      newStateLevel[path[i]] = event.target.value;
    } else {
      newStateLevel[path[i]] = { ...oldStateLevel[path[i]] };
      oldStateLevel = oldStateLevel[path[i]];
      newStateLevel = newStateLevel[path[i]];
    }
  }
  this.setState(newstate);
}

setState as @Qwerty's answer

updateState(event) {
  const path = event.target.name.split('.');
  const depth = path.length;
  const state = { ...this.state };
  let ref = state;
  for (let i = 0; i < depth; i += 1) {
    if (i === depth - 1) {
      ref[path[i]] = event.target.value;
    } else {
      ref = ref[path[i]];
    }
  }
  this.setState(state);
}

Note: These above methods won't work for arrays

Answer 3

Although you asked about a state of class-based React component, the same problem exists with useState hook. Even worse: useState hook does not accept partial updates. So this question became very relevant when useState hook was introduced.

I have decided to post the following answer to make sure the question covers more modern scenarios where the useState hook is used:

If you have got:

const [state, setState] = useState({ someProperty: { flag: true, otherNestedProp: 1 }, otherProp: 2 })

you can set the nested property by cloning the current and patching the required segments of the data, for example:

setState(current => { ...current, someProperty: { ...current.someProperty, flag: false } });

Or you can use Immer library to simplify the cloning and patching of the object.

Or you can use Hookstate library (disclaimer: I am an author) to simply the management of complex (local and global) state data entirely and improve the performance (read: not to worry about rendering optimization):

import { useStateLink } from '@hookstate/core' 
const state = useStateLink({ someProperty: { flag: true, otherNestedProp: 1 }, otherProp: 2 })

get the field to render:

state.nested.someProperty.nested.flag.get()
// or 
state.get().someProperty.flag

set the nested field:

state.nested.someProperty.nested.flag.set(false)

Here is the Hookstate example, where the state is deeply / recursively nested in tree-like data structure.

Answer 4

Although nesting isn't really how you should treat a component state, sometimes for something easy for single tier nesting.

For a state like this

state = {
 contact: {
  phone: '888-888-8888',
  email: 'test@test.com'
 }
 address: {
  street:''
 },
 occupation: {
 }
}

A re-useable method ive used would look like this.

handleChange = (obj) => e => {
  let x = this.state[obj];
  x[e.target.name] = e.target.value;
  this.setState({ [obj]: x });
};

then just passing in the obj name for each nesting you want to address...

<TextField
 name="street"
 onChange={handleChange('address')}
 />

Answer 5

If you are using ES2015 you have access to the Object.assign. You can use it as follows to update a nested object.

this.setState({
  someProperty: Object.assign({}, this.state.someProperty, {flag: false})
});

You merge the updated properties with the existing and use the returned object to update the state.

Edit: Added an empty object as target to the assign function to make sure the state isn't mutated directly as carkod pointed out.

Answer 6

This is my initialState

    const initialStateInput = {
        cabeceraFamilia: {
            familia: '',
            direccion: '',
            telefonos: '',
            email: ''
        },
        motivoConsulta: '',
        fechaHora: '',
        corresponsables: [],
    }

The hook or you can replace it with the state (class component)

const [infoAgendamiento, setInfoAgendamiento] = useState(initialStateInput);

The method for handleChange

const actualizarState = e => {
    const nameObjects = e.target.name.split('.');
    const newState = setStateNested(infoAgendamiento, nameObjects, e.target.value);
    setInfoAgendamiento({...newState});
};

Method for set state with nested states

const setStateNested = (state, nameObjects, value) => {
    let i = 0;
    let operativeState = state;
    if(nameObjects.length > 1){
        for (i = 0; i < nameObjects.length - 1; i++) {
            operativeState = operativeState[nameObjects[i]];
        }
    }
    operativeState[nameObjects[i]] = value;
    return state;
}

Finally this is the input that I use

<input type="text" className="form-control" name="cabeceraFamilia.direccion" placeholder="Dirección" defaultValue={infoAgendamiento.cabeceraFamilia.direccion} onChange={actualizarState} />