How to pass params to other screen in React Native? - reactjs

Question

My React Js skills are very basic,What I want to get is when I click on a category, I show a list of posts of the category selected in a new screen in this case is PostsScreen.
The problem is that i get the itemId null.
I don't know what i'm doing wrong.
Categories Screen
import React, {Component} from 'react';
import { NavigationActions, DrawerNavigator, StackNavigator } from 'react-navigation';
import{Dimensions, Button, View, SafeAreaView, FlatList, ActivityIndicator, TouchableOpacity } from 'react-native';
export default class WGoals extends Component {
static navigationOptions = {
title: 'Categories'
};
navigateToScreen = (route, params) => () => {
const navigateAction = NavigationActions.navigate({
routeName: route,
params: params
});
this.props.navigation.dispatch(navigateAction);
}
constructor(props)
{
super(props);
this.state = {
isLoading: true,
}
}
render() {
return (
<Container style={styles.background_general}>
<TouchableOpacity onPress={this.navigateToScreen('PostsScreen', itemId = '1')} >
<Text>Category 1</Text>
</TouchableOpacity>
<TouchableOpacity onPress={this.navigateToScreen('PostsScreen', itemId = '2')} >
<Text>Category 2</Text>
</TouchableOpacity>
</Container>
);
}
}
Posts Screen
import React, {Component} from 'react';
import { NavigationActions, DrawerNavigator, StackNavigator } from 'react-navigation';
import{Dimensions, View, SafeAreaView, FlatList, ActivityIndicator } from 'react-native';
export default class Posts extends Component {
static navigationOptions = {
title: 'Posts'
};
render() {
const { params } = this.props.navigation.state;
const itemId = params ? params.itemId : null;
return (
<Container style={styles.background_general}>
<Text>Details Screen</Text>
<Text>itemId: {JSON.stringify(itemId)}</Text>
</Container>
);
}
}

Answer 1

Change arguments of your function
this.navigateToScreen('PostsScreen', itemId = '1')
to
this.navigateToScreen('PostsScreen', {itemId: '1'})