How do I update an array using the useContext hook? - reactjs

Question

I've set a Context, using createContext, and I want it to update an array that will be used in different components. This array will receive the data fetched from an API (via Axios).
Here is the code:
Context.js
import React, { useState } from "react";
const HeroContext = React.createContext({});
const HeroProvider = props => {
const heroInformation = {
heroesContext: [],
feedHeroes: arrayFromAPI => {
setHeroesContext(...arrayFromAPI);
console.log();
}
};
const [heroesContext, setHeroesContext] = useState(heroInformation);
return (
<HeroContext.Provider value={heroesContext}>
{props.children}
</HeroContext.Provider>
);
};
export { HeroContext, HeroProvider };
See above that I created the context, but set nothing? Is it right? I've tried setting the same name for the array and function too (heroesContex and feedHeroes, respectively).
Component.js
import React, { useContext, useEffect } from "react";
import { HeroContext } from "../../context/HeroContext";
import defaultSearch from "../../services/api";
const HeroesList = () => {
const context = useContext(HeroContext);
console.log("Just the context", context);
useEffect(() => {
defaultSearch
.get()
.then(response => context.feedHeroes(response.data.data.results))
.then(console.log("Updated heroesContext: ", context.heroesContext));
}, []);
return (
//will return something
)
In the Component.js, I'm importing the defaultSearch, that is a call to the API that fetches the data I want to push to the array.
If you run the code right now, you'll see that it will console the context of one register in the Just the context. I didn't want it... My intention here was the fetch more registers. I have no idea why it is bringing just one register.
Anyway, doing all of this things I did above, it's not populating the array, and hence I can't use the array data in another component.
Does anyone know how to solve this? Where are my errors?

Answer 1

The issue is that you are declaring a piece of state to store an entire context object, but you are then setting that state equal to a single destructured array.
So you're initializing heroesContext to
const heroInformation = {
heroesContext: [],
feedHeroes: arrayFromAPI => {
setHeroesContext(...arrayFromAPI);
console.log();
}
};
But then replacing it with ...arrayFromAPI.
Also, you are not spreading the array properly. You need to spread it into a new array or else it will return the values separately: setHeroesContext([...arrayFromAPI]);
I would do something like this:
const HeroContext = React.createContext({});
const HeroProvider = props => {
const [heroes, setHeroes] = useState([]);
const heroContext = {
heroesContext: heroes,
feedHeroes: arrayFromAPI => {
setHeroes([...arrayFromAPI]);
}
};
return (
<HeroContext.Provider value={heroContext}>
{props.children}
</HeroContext.Provider>
);
};
export { HeroContext, HeroProvider };