react-native - Picker - undefined 不是一个对象(评估'this.props.children[position].props) [英] react-native - Picker - undefined is not an object (evaluating 'this.props.children[position].props)
问题描述
我在使用 Picker 时遇到了一个奇怪的行为.
I am encountering a weird behaviour when using Picker.
我使用 Picker 如下:
I use a Picker as follows :
<Picker
mode="dropdown"
style={styles.pickerField}
selectedValue={this.state.dayAndTime}
onValueChange={(text) => this.setState({ dayAndTime: text })}
>
<Picker.Item label="Le 5/07 à 15H" value="0" key="0" />
</Picker>
当显示此选择器的屏幕加载时,我收到一个错误屏幕说(参见下面的屏幕截图):未定义不是对象(评估 'this.props.children[position].props)
When the screen displaying this picker is loaded, I got an error screen saying (cf. screenshot below) : undefined is not an object (evaluating 'this.props.children[position].props)
从我收集到的信息来看,我的问题来自于 Libraries/Components/Picker/PickerAndroid.android.js 的第 106 行,似乎有一个属性onValueChange"触发了它.我删除了它,并没有发生错误.
From what I gathered, my problem come from line 106 of Libraries/Components/Picker/PickerAndroid.android.js, it seems that having a property "onValueChange" triggers it. I removed it, and error didn't happen.
我使用 react-native 0.31.0,我使用带有 genymotion 的 android api 23 虚拟设备.
I use react-native 0.31.0, I use an android api 23 virtual device with genymotion.
我做错了什么吗?
推荐答案
必须至少有 2 个项目可供选择,例如:<代码><Picker.Item label="Le 5/07 à 15H" value="0" key="0"/><Picker.Item label="Le 5/07 à 15H" value="1" key="1"/>
There must be at least 2 items to pick from, for example:
<Picker.Item label="Le 5/07 à 15H" value="0" key="0" />
<Picker.Item label="Le 5/07 à 15H" value="1" key="1" />
为了更好的语法,您可以尝试:<代码>onValueChange={(dayAndTime) =>this.setState({ dayAndTime })}
Also for better syntax you can try:
onValueChange={(dayAndTime) => this.setState({ dayAndTime })}
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