Use setState to change the value of a grandchild object

Question

Everything I have tried from what I can find doesn't seem to be working. I'm really curious how to access and edit grandchild objects located in the state with react. If anyone could tell me what I'm doing wrong, it would be very helpful.

https://codesandbox.io/s/0mo32q85pp

Take a look at the following code...

App.js

lines: 41-58

getHomeworld = URL => {
  fetch(URL)
    .then(res => {
      return res.json();
    })
    .then(homeWorldObject => {
      console.log(homeWorldObject);
      // this.setState({ <- Why isn't this working????
      //   ...this.state.starwarsChars,
      //   ...this.state.nextPage,
      //   ...this.state.prevPage,
      //   ...this.state.starwarsChars.homeworld = homeWorldObject
      // });
    })
    .catch(err => {
      throw new Error(err);
    });
};

lines: 86-89

<CharacterList
  characters={this.state.starwarsChars}
  getHomeworld={this.getHomeworld}
/>

CharacterList.js

lines: 8-12

<Character
  key={character.name}
  characterDetails={character}
  getHomeworld={props.getHomeworld}
/>

Character.js

lines: 18-29

{Object.keys(props.characterDetails).includes("homeworld") ? (
  <div className="character-homeworld">
    <Homeworld
      homeworld={props.getHomeworld(props.characterDetails.homeworld)}
    />
  </div>
) : (
  <div className="character-homeworld">
    <h4>Homeworld</h4>
    <p>None</p>
  </div>
)}

Homeworld.js

lines: 7-10

<div className="homeworld-details">
  <p>Name: {props.name}</p>
  <p>Rotation Period: {props.rotation_period}</p>
</div>

Expected Output: If you look on the sandbox webpage, the "Name" and "Rotation Period" (Under "Homeworld") should display the values from here: https://swapi.co/api/planets/1/

Is there anyone who can help me figure this out?

---

EDIT:

I got really close making these changes (using my local machine, the code on the sandbox is still the original)...

App.js

let temp = {...this.state.starwarsChars} // use spread operator to clone it, so you don't mutate state on next line;
for (let character in temp) {
  if (temp[character].homeworld === URL) {
    temp[character].homeworld = homeWorldObject;
  }
}
// console.log(temp);
this.setState({
  starwarsChars: temp
});

Character.js

const Character = props => {
  props.getHomeworld(props.characterDetails.homeworld);
  console.log(props.characterDetails); // returns object{homeworld: {object}}
  console.log(props.characterDetails.homeworld); // returns url

and...

<div className="character-homeworld">
  <Homeworld
    homeworld={props.characterDetails.homeworld}/>
</div>

However, the issue now is if I do console.log(props.characterDetails.homeworld);, it logs homeworld: url

and...

if I do console.log(props.characterDetails);, it logs the property of the character object as homeworld: {object}

...

What I want is the 2nd one, and I'm not sure why it's not consistent.

---

Update

For some strange reason, codesandbox is console logging both urls, and when I run with yarn start, it logs the url for one, and the object for another. Because of this... I am adding the github link here -> https://github.com/jamespagedev/Sprint-Challenge-React-Wars (so the error can properly be reproduced)

---

Edit 2:

I changed the sandbox code to the following so we are now only worrying about the code in 1 file -> https://codesandbox.io/s/0mo32q85pp

Here is the issue I am now seeing, and I'm not sure how to solve it...

getHomeworld = URL => {
  let home;
  fetch(URL)
  .then(res => res.json())
  .then(homeWorldObject => {
    home = homeWorldObject;
    console.log(home); // home is an object
  });
  console.log(home); // why is home undefined?
  return home;
};

I've tried doing return homeWorldObject, but the main function just returns undefined. After doing the console logging, that was what I found, and I'm not sure why that is happening...