Getting error while entering data via AsyncStorage React-native

Question

I getting an error while I try to put data for my cart system.

I can put data when I try [json]; but I couldn't when I change it to[...json];

[json]; is giving me the last item that I put but I need all of them

addCart=()=>{



  const sepets = AsyncStorage.getItem("sepet")
   .then(req => {
   const json =  JSON.parse(req); 
   const sepet=[...json];
   sepet.push({isim:this.props.title,fiyat:this.props.fiyat,image:this.props.image});

   AsyncStorage.setItem("sepet",JSON.stringify(sepet));


   });




    }

the error that gives me "Possible Unhandled Promise Rejection (id: 0): TypeError: Invalid attempt to spread non-iterable instance TypeError: Invalid attempt to spread non-iterable instance at _nonIterableSpread "

I'm removing items like this export default class aksiyos extends React.Component {

        constructor(props) {
        super(props);
        this.state = {
          ApiTitle: [],
        }
      }

          componentDidMount() {


       var sepet=AsyncStorage.getItem("sepet").then(req=>JSON.parse(req)).then(json=>{

      this.setState({ApiTitle: json });


       });




      }

      removeCart=()=>{

        AsyncStorage.removeItem("sepet")
      }
        render() {
        return (
          <View style={{backgroundColor: "white"}}>
          <ScrollView>{this.state.ApiTitle.map((ids, i)=>

            <Text>{ids.isim}</Text>


    )}
            </ScrollView>
                            <Text onPress={this.removeCart}>Buton</Text>
            </View>
        );
      }
     }

`

Answer 1

You don't need the extra .then() when you parse your data. You need to also check for null, after removing the items, getItem will return null.

const sepets = AsyncStorage.getItem("sepet")
 .then(req => {

 let json =  JSON.parse(req);

 if (!json) {
   json = [];
 }

 const sepet=[...json];
 sepet.push({isim:this.props.title,fiyat:this.props.fiyat,image:this.props.image});

 AsyncStorage.setItem("sepet",JSON.stringify(sepet));

 console.log(sepet)

 });

In your render validate ApiTitle before using it.

render() {

  const items = this.state.ApiTitle || [];

  return (
    <View style={{ backgroundColor: "white" }}>
      <ScrollView>{items.map((ids, i) =>
        <Text>{ids.isim}</Text>
      )}
      </ScrollView>
      <Text onPress={this.removeCart}>Buton</Text>
    </View>
  );
}