Passing parameters to routes
Remember when I said "more on that later when we talk about params
!"? Well, the time has come.
Now that we know how to create a stack navigator with some routes and navigate between those routes, let's look at how we can pass data to routes when we navigate to them.
There are two pieces to this:
- Pass params to a route by putting them in an object as a second parameter to the
navigation.navigate
function:navigation.navigate('RouteName', { /* params go here */ })
- Read the params in your screen component:
route.params
.
We recommend that the params you pass are JSON-serializable. That way, you'll be able to use state persistence and your screen components will have the right contract for implementing deep linking.
function HomeScreen() {
const navigation = useNavigation();
return (
<View style={{ flex: 1, alignItems: 'center', justifyContent: 'center' }}>
<Text>Home Screen</Text>
<Button
onPress={() => {
/* 1. Navigate to the Details route with params */
navigation.navigate('Details', {
itemId: 86,
otherParam: 'anything you want here',
});
}}
>
Go to Details
</Button>
</View>
);
}
function DetailsScreen({ route }) {
const navigation = useNavigation();
/* 2. Get the param */
const { itemId, otherParam } = route.params;
return (
<View style={{ flex: 1, alignItems: 'center', justifyContent: 'center' }}>
<Text>Details Screen</Text>
<Text>itemId: {JSON.stringify(itemId)}</Text>
<Text>otherParam: {JSON.stringify(otherParam)}</Text>
<Button
onPress={
() =>
navigation.push('Details', {
itemId: Math.floor(Math.random() * 100),
})
}
>
Go to Details... again
</Button>
<Button onPress={() => navigation.navigate('Home')}>Go to Home</Button>
<Button onPress={() => navigation.goBack()}>Go back</Button>
</View>
);
}
Initial params
You can also pass some initial params to a screen. If you didn't specify any params when navigating to this screen, the initial params will be used. They are also shallow merged with any params that you pass. Initial params can be specified in initialParams
:
- Static
- Dynamic
{
Details: {
screen: DetailsScreen,
initialParams: { itemId: 42 },
},
}
<Stack.Screen
name="Details"
component={DetailsScreen}
initialParams={{ itemId: 42 }}
/>
Updating params
Screens can also update their params, like they can update their state. The navigation.setParams
method lets you update the params of a screen. Refer to the API reference for setParams
for more details.
Basic usage:
navigation.setParams({
itemId: Math.floor(Math.random() * 100),
})
Avoid using setParams
to update screen options such as title
etc. If you need to update options, use setOptions
instead.
Passing params to a previous screen
Params aren't only useful for passing some data to a new screen, but they can also be useful to pass data to a previous screen as well. For example, let's say you have a screen with a "Create post" button, and the button opens a new screen to create a post. After creating the post, you want to pass the data for the post back to the previous screen.
To achieve this, you can use the popTo
method to go back to the previous screen as well as pass params to it:
function HomeScreen({ route }) {
const navigation = useNavigation();
// Use an effect to monitor the update to params
React.useEffect(() => {
if (route.params?.post) {
// Post updated, do something with `route.params.post`
// For example, send the post to the server
alert('New post: ' + route.params?.post);
}
}, [route.params?.post]);
return (
<View style={{ flex: 1, alignItems: 'center', justifyContent: 'center' }}>
<Button onPress={() => navigation.navigate('CreatePost')}>
Create post
</Button>
<Text style={{ margin: 10 }}>Post: {route.params?.post}</Text>
</View>
);
}
function CreatePostScreen({ route }) {
const navigation = useNavigation();
const [postText, setPostText] = React.useState('');
return (
<>
<TextInput
multiline
placeholder="What's on your mind?"
style={{ height: 200, padding: 10, backgroundColor: 'white' }}
value={postText}
onChangeText={setPostText}
/>
<Button
onPress={() => {
// Pass params back to home screen
navigation.popTo('Home', { post: postText });
}}
>
Done
</Button>
</>
);
}
Here, after you press "Done", the home screen's route.params
will be updated to reflect the post text that you passed in navigate
.
Passing params to a nested screen
If you have nested navigators, you need to pass params a bit differently. For example, say you have a navigator inside the More
screen and want to pass params to the Settings
screen inside that navigator. Then you can pass params as the following:
navigation.navigate('More', {
screen: 'Settings',
params: { user: 'jane' },
})
See Nesting navigators for more details on nesting.
What should be in params
Params are essentially options for a screen. They should contain the minimal data required to show a screen, nothing more. If the data is used by multiple screens, it should be in a global store or global cache. Params is not designed for state management.
You can think of the route object as a URL. If your screen had a URL, what should be in the URL? The same principles apply to params. Think of visiting a shopping website; when you see product listings, the URL usually contains category name, type of sort, any filters etc., not the actual list of products displayed on the screen.
For example, say if you have a Profile
screen. When navigating to it, you might be tempted to pass the user object in the params:
// Don't do this
navigation.navigate('Profile', {
user: {
id: 'jane',
firstName: 'Jane',
lastName: 'Done',
age: 25,
},
});
This looks convenient and lets you access the user objects with route.params.user
without any extra work.
However, this is an anti-pattern. There are many reasons why this is a bad idea:
-
The same data is duplicated in multiple places. This can lead to bugs such as the profile screen showing outdated data even if the user object has changed after navigation.
-
Each screen that navigates to the
Profile
screen now needs to know how to fetch the user object - which increases the complexity of the code. -
URLs to the screen (browser URL on the web, or deep links on native) will contain the user object. This is problematic:
- Since the user object is in the URL, it's possible to pass a random user object representing a user that doesn't exist or has incorrect data in the profile.
- If the user object isn't passed or improperly formatted, this could result in crashes as the screen won't know how to handle it.
- The URL can become very long and unreadable.
A better way is to pass only the ID of the user in params:
navigation.navigate('Profile', { userId: 'jane' });
Now, you can use the passed userId
to grab the user from your global store. This eliminates a host of issues such as outdated data, or problematic URLs.
Some examples of what should be in params are:
- IDs like user id, item id etc., e.g.
navigation.navigate('Profile', { userId: 'Jane' })
- Params for sorting, filtering data etc. when you have a list of items, e.g.
navigation.navigate('Feeds', { sortBy: 'latest' })
- Timestamps, page numbers or cursors for pagination, e.g.
navigation.navigate('Chat', { beforeTime: 1603897152675 })
- Data to fill inputs on a screen to compose something, e.g.
navigation.navigate('ComposeTweet', { title: 'Hello world!' })
In essence, pass the least amount of data required to identify a screen in params, for a lot of cases, this simply means passing the ID of an object instead of passing a full object. Keep your application data separate from the navigation state.
Summary
navigate
andpush
accept an optional second argument to let you pass parameters to the route you are navigating to. For example:navigation.navigate('RouteName', { paramName: 'value' })
.- You can read the params through
route.params
inside a screen - You can update the screen's params with
navigation.setParams
- Initial params can be passed via the
initialParams
prop onScreen
- Params should contain the minimal data required to show a screen, nothing more