"Text strings must be rendered within a Text component" when && operator is used in JSX

[mattermoran]

@hramos here. This issue has been modified from its original content, in order to convey the latest status of this issue. You may refer to the edit history to see what @mattermoran originally reported.

Environment:

[skip envinfo]

This issue only affected Android in older releases, but is now consistent across both iOS and Android platforms as of 0.57.8.

Description

Using JSX that conditionally renders a Text element can lead to a RedBox error, "Invariant Violation: Text strings must be rendered within a Text component", if the condition is "falsy", as in the following example:

<View>
  {someTextValue && <Text>{someTextValue}</Text>}
</View>

This can lead to a confusing development experience, as the pattern is documented in React's JSX docs.

Workaround

Use a ternary operator.

<View>
  {someTextValue ? <Text>{someTextValue}</Text> : null}
</View>

[react-native-bot]

Can you reproduce the issue on the latest release, v0.56?

[mattermoran]

@react-native-bot I'm using create-react-native-app and I believe the latest one there is 0.52.2
I tried upgrading it to 0.56 but that caused some errors

[ATShiTou]

String should not be children of View, Use Text instead.

this.state.name && <Text>{ this.state.name }</Text>

[mattermoran]

@ATShiTou sorry I just put view in the example but using Text doesn't fix the issue.

[ATShiTou]

I have been using && in JSX all the time, and never crash for this.

[ATShiTou]

Two layers of parentheses in your code:

this.state.name && <View>{{ this.state.name }}</View>

is wrong.

[mattermoran]

@ATShiTou my bad it should be one but then again it still crashes. I've also been using it in react and react native on ios without any problem. But for some reason same code that works just fine on ios crashes on android.

[ATShiTou]

I guess that some characters are incorrect and ignored.

For this code:

<View><View />></View>

It works well on iOS, but crashes on Android.

Check your code please.

[mattermoran]

@ATShiTou Here's the screenshot of what works on ios but crashes the app on android

The ternary operator like this works fine on both platform

[ATShiTou]

What about the crash log ?

[mattermoran]

@ATShiTou btw interesting thing that I noticed. Let's say I have the state nickname: null and when I fetch data and the state becomes nickname: 'alex' then app will crash. I did more tests and apparently it doesn't work with strings on android but other types like null, undefined or an object are fine. iOS handles that without a problem though. I can check logs now

UPDATE:
so actually it crashes ONLY with empty string like nickname: ''

[ravirajn22]

I know whats going wrong,

The below code works without crashing in iOS whereas it crashes in Android.
I checked it snack.expo v29.0.0.

<View style={styles.container}>
        {'' && <Text style={styles.paragraph}>I am here</Text>}
</View>

Leaving aside the crash, you should not render a empty string without wrapping it in Text for now in React-Native.
In these case you must do,

<View style={styles.container}>
        // Change any variable to boolean using double exclamation !!
        {!!'' && <Text style={styles.paragraph}>I am here</Text>}
</View>

By the way still this is a bug in RN, to maintain compatability either it should crash in both iOS and Android or it should emit omit empty string('') altogether.