Update state array in React Native

Question

I'm trying to fill an empty state array with the elements of a Firebase database

retrieveCategories = async () => {
 const { categories } = this.state;
 const { eventTypes } = constants;
 let count = eventTypes;

 const snapshot = await firebase.database().ref('/categories').once('value');

 while (count !== -1) {
   const cat = snapshot.val()[count];
   this.setState(prevState => ({ categories: [...prevState.categories, cat] }));
   count -= 1;
 }

 console.log(categories);
}

The problem is that no matter what I do, the array does not update itself, proven when the console.log(categories); only throws a [].

What can I do to solve this issue?

Ali Hayder · Accepted Answer · 2020-05-08 18:26:36Z

1

You can do it like this

let {categories} = this.state
categories.push(cat)
this.setState({categories})

Also console.log(this.state.categories) because the state is updated after this.setState.

answered May 8, 2020 at 18:26

Ali Hayder

3251 silver badge9 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Update state array in React Native

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related