Possible unhandled promise rejection (id 0) typeerror Body not allowed for GET or HEAD requests

Question

import React from 'react';
import { FlatList, ActivityIndicator, Text, View  } from 'react-native';

export default class FetchExample extends React.Component {

  constructor(props){
    super(props);
    this.state ={ isLoading: true}
  }

  componentDidMount(){

        fetch('https://apitest.kuveytturk.com.tr/prep/v1/data/fecs', {
             method: 'GET',
             headers: {
               Accept: 'application/json',
               'Content-Type': 'application/json',
             },
             body: JSON.stringify({
               firstParam: 'isoCode ',
               secondParam: 'internationalCode',
               thirdParam: 'name',
               fourthParam: 'code',
               FifthParam: 'group',
               SixthParam: 'id'
             }),
           });

}


  render(){

    if(this.state.isLoading){
      return(
        <View style={{flex: 1, padding: 20}}>
          <ActivityIndicator/>
        </View>
      )
    }

    return(
      <View style={{flex: 1, paddingTop:20}}>
        <FlatList
          data={this.state.dataSource}
          renderItem={({item}) => <Text>{item.isoCode}, {item.internationalCode}, {item.name}, {item.code}, {item.group}</Text>}
          keyExtractor={({id}, index) => id}
        />
      </View>
    );
  }
}

I am the beginner of react native and i am trying to get data from api but i have an error about code.

possible unhandled promise rejection (id 0) typeerror undefined is not an object

I can't understand why there is no object

Hope for your help.

Answer 1

Please note that you cannot use body in GET Request. Please change it to POST.