How to pass state from context

JavaScript
1

I’m trying to make my context work properly.
I’ve added it and it works as it should if I pass a string as a property to the state. However, I want to pass a prop as the state.

So this works:

 export class DataProvider extends Component {
      constructor(props) {
        super(props);
        this.state = {
          continent: props.continent,
        };
        this.updateState = this.updateState.bind(this);
      }
    
      updateState() {
        this.setState({ continent: this.props.continent});
      }
    
      componentDidMount() {
        console.log(this.props.continent);
        this.updateState();
      }
    
      render() {
        return (
          <DataContext.Provider value={{ state: this.state }}>
            {this.props.children}
          </DataContext.Provider>
        );
      }
    }

But this does not work (results in undefined)

this.state = {
          continent: props.continent,
        };

Results in “undefined” when I try to access it.

I get the prop from a component named “Africa”, which does this:

 const Africa = ({}) => {
      return (
        <div>
           <DataProvider continent={["Africa"]} /> 
    ........irrelevant code

It successfully passes to my DataProvider component.
But, as I stated, when I try to pass that as a property for my state, it results in “undefined”.

  class JumbotronPage extends Component {
      static contextType = DataContext;
    
      render() {
        console.log(this.context)

A(DataProvider), B(Africa), C(JumbotronPage)
I’m not sure if it’s because A and B recognizes each other.
B and C does not.

So whenever I access C from A, B gets re-rendered, resulting in giving C nothing as state. Does that make sense?

Please, forgive me for being very green and new to React. I hope I make some sense.

This is part of my App.js:

  <Route exact path="/Login" component={Login} />
                
                <Route exact path="/Jumbotron">
                  <DataProvider>
                    <JumbotronPage />
                  </DataProvider>
                </Route>
                <Route exact path="/CreateNewMemories" component={renderForm} />

I created a gist, if someone has the time an patience to have a look at my abomination.

https://gist.github.com/kalleftw/e79412034eafd29a2e26b1af24149e67

I understand that using this technique for passing contexts is quite outdated, however, I am very new to React and this was the way that I understood (best).

2

I’m not familiar with React yet.

A stab at it though, is the issue with the Africa component? — DataProvider is a new one to me.

Have you tried stripping the code right back, process of elimination?

A simple test, with not knowing what Component does

// dummy Component class
class Component {
    constructor(props){
        // Object.assign(this, props)
    }
}

class DataProvider extends Component {
    constructor(props) {
        super(props);
        this.state = {
            continent: props.continent
        };
    }
}

let dataProv = new DataProvider({
    continent: 'Africa'
})

console.dir(dataProv)

Output

v DataProvider
  v state:
    continent: "Africa"
    > __proto__: Object
  > __proto__: Component

Not sure what I am missing, but in theory this should work???

3

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