I'm new to react-native, I'm trying to use Picker item to selct from a dropdown, I'm using react hooks to set Picker items to be selectable, however Expo stops without warning when I add the code:
const HomeScreen3 = observer(() =>
{
const [ options, setOptions ] = useState([ { id:1, title:'Titulo 1' }, { id:2, title:'Titulo 2' } ]);
const [ selectedOption, setSelectedOption ] = useState({ id:1, title:'Titulo 1' });
useEffect(() => {
console.log('component mounted');
}, []);
return (
<View style={{flex: 1, backgroundColor: '#fff', padding:10, position:'relative' }}>
<ScrollView showsHorizontalScrollIndicator={false}>
<Picker
itemStyle={{ backgroundColor: "white", color: "black", borderColor:'rgba(0,0,0,0.2)', fontSize:16, }}
mode="dropdown"
selectedValue={selectedOption}
onValueChange={(value) => { setSelectedOption( value)}}>
{options.map((item, index) => {
return (<Picker.Item label={item} value={item} key={index}/>)
})}
</Picker>
</ScrollView>
</View>
export default HomeScreen3;
First of all, in Expo SDK 38 the import { Picker } from 'react-native';
is no longer working as expected.
Make sure you use import { Picker } from '@react-native-community/picker';
Here is the documentation for it: https://github.com/react-native-community/react-native-picker .
Second, the real problem I see is an issue with your code is that for the Picker.Item
, here:
{options.map((item, index) => {
return (<Picker.Item label={item} value={item} key={index}/>)
})}
you are sending the complete objects in the label
and item
props. However, looking at the actual documentation, label accepts a string and value accepts string or integer - https://reactnative.dev/docs/picker-item
That means your Picker
code should look like this:
<Picker
itemStyle={{backgroundColor: "white", color: "black", borderColor:'rgba(0,0,0,0.2)', fontSize:16}}
mode="dropdown"
selectedValue={selectedOption}
onValueChange={(value) => {setSelectedOption(value)}}>
{options.map((item, index) => {
return (<Picker.Item label={item.id} value={item.title} key={index}/>)
})}
</Picker>
and the selectedOption
should only store the id of the item like this:
const [ selectedOption, setSelectedOption ] = useState(1);
for expo use this works for me even is there a warn but works!
import { Picker } from 'react-native'
// state
const [picked, setPicked] = useState(1.15);
<Picker
selectedValue={picked}
style={{ height: 50, width: 100 }}
onValueChange={(itemValue, itemIndex) =>
setPicked(itemValue)
}>
<Picker.Item label="Canda 5%" value={1.05} />
<Picker.Item label="Japan 8%" value={1.08} />
<Picker.Item label="USA 10%" value={1.10} />
<Picker.Item label="Egypt 14%" value={1.14} />
<Picker.Item label="Saudi Arabia 15%" value={1.15} />
<Picker.Item label="China 16%" value={1.16} />
<Picker.Item label="Algeria 17%" value={1.17} />
<Picker.Item label="18%" value={1.18} />
<Picker.Item label="German 19%" value={1.19} />
<Picker.Item label="German 19%" value={1.20} />
</Picker>
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