如何默认select第一个值？

Question

我有来自 native-base 的 Picker 组件。我希望默认情况下自动选择第一个值

来自数据库 "vaccinationSchemas" 即将到来。我希望数据被选中。

let vacineFormData: any = {
  id: generateUUID(),
  medicineId: "",
  animalId: "",
  diseaseId: "",
  taskId: "",
  analysisTubeId: "",
  eventDate: new Date(),
  vaccinationSchemaId: "",
};

vacineFormPropUpdate(prop: string, value: any) {
    const { vacineFormData } = this.state;
    this.setState({
      vacineFormData: {
        ...vacineFormData,
        [prop]: value,
      },
    });
  }

const schemasData = vaccinationSchemas.map(v=>({
      label:v.id,
      value:v.id
    }))
<Picker
      data={schemasData}
      value={vacineFormData.vaccinationSchemaId}
      onValueChange={v => 
      this.vacineFormPropUpdate("vaccinationSchemaId",v)}
      placeholder={t("global_vaccination_schemas")}
 />

Answer 1

handleChangeOption(val) {
  if (val !== 0) {
    this.setState({selectedValue: val});
  }
}


<View style={Styles.row}>
            <Picker
                selectedValue={this.state.selectedValue}
                onValueChange={this.handleChangeOption}
              >
              {schemasData.map(item=>
              <Picker.Item label={item.label} value={item.value} />)
              }
            </Picker>
</View>

如何默认select第一个值？

How to select the first value by default?

javascript

react-native

native-base