react使用TypeScript选择async loadOptions

Question

我正在将一个现有的react应用程序转换为typescript，并且我很难将react-select异步loadOptions正确解析为typescript。

export type userType = {
loginId: string,
firstName: string,
lastName: string,
email: string,
}
<AsyncSelect
id={n.id}
name={n.id}
isClearable={true}
onBlur={handleBlur}
onChange={onChange}
placeholder={"Search by name, email or login ID"}
value={input}
className={input_class}
loadOptions={loadOptions}
/>

const loadOptions = async (inputText: string, callback: any) => {
axios.get(`myAPI_URI`)
.then((response) => {
let data: userType[] = response.data.results;
return data.map(result => {
return labelFormatter(result)
})
});
}
const labelFormatter = (i: any) => {
return {
label: i.loginId + ' - ' + i.firstName + ' ' + i.lastName + ' - ' + i.email,
value: i.loginId,
}
}

错误为

No overload matches this call.
Overload 1 of 2, '(props: Props<filteredOptionType, false, GroupTypeBase<filteredOptionType>> | Readonly<Props<filteredOptionType, false, GroupTypeBase<...>>>): Async<...>', gave the following error.
Type '(inputText: string, callback: any) => Promise<void>' is not assignable to type '(inputValue: string, callback: (options: readonly (filteredOptionType | GroupTypeBase<filteredOptionType>)[]) => void) => void | Promise<...>'.
Type 'Promise<void>' is not assignable to type 'void | Promise<readonly (filteredOptionType | GroupTypeBase<filteredOptionType>)[]>'.
Type 'Promise<void>' is not assignable to type 'Promise<readonly (filteredOptionType | GroupTypeBase<filteredOptionType>)[]>'.
Type 'void' is not assignable to type 'readonly (filteredOptionType | GroupTypeBase<filteredOptionType>)[]'.
Overload 2 of 2, '(props: Props<filteredOptionType, false, GroupTypeBase<filteredOptionType>>, context: any): Async<filteredOptionType, false, GroupTypeBase<...>>', gave the following error.
Type '(inputText: string, callback: any) => Promise<void>' is not assignable to type '(inputValue: string, callback: (options: readonly (filteredOptionType | GroupTypeBase<filteredOptionType>)[]) => void) => void | Promise<...>'.  TS2769

我不知道在哪里需要声明loadOptions的返回类型才能按预期工作。

Answer 1

如果这是loadOptions函数的实际代码，那么它有几个问题：

• 它不返回任何有意义的值(它返回undefined，并且考虑到async，它具有返回类型Promise<void>(
• 它没有副作用

从实用的角度来看，它没有任何用处，只是丢弃了响应数据。

---

要修复此问题，您可以采取以下方法之一：

1. 返回一些有用的东西。然后您必须注释函数的返回类型：

import { OptionTypeBase } from "react-select/src/types"
const labelFormatter = (i: userType): OptionTypeBase => {
return {
label: i.loginId + ' - ' + i.firstName + ' ' + i.lastName + ' - ' + i.email,
value: i.loginId,
}
}
// add `return` keyword
const loadOptions = async (
inputText: string, 
callback: any
): Promise<OptionTypeBase[]> => {
return axios.get(`myAPI_URI`)
.then((response) => {
let data: userType[] = response.data.results;
return data.map(result => {
return labelFormatter(result)
})
});
}
// or remove curly braces
const loadOptions = async (
inputText: string, 
callback: any
): Promise<OptionTypeBase[]> => 
axios.get(`myAPI_URI`)
.then((response) => {
let data: userType[] = response.data.results;
return data.map(result => {
return labelFormatter(result)
})
});

2. 或产生副作用：

// no `async` keyword. and using callback inside the function body
const loadOptions = (
inputText: string,
callback: (options: OptionTypeBase[]) => void
): void => {
axios.get(`myAPI_URI`).then((response) => {
let data: userType[] = response.data.results;
callback(data.map((result) => {
return labelFormatter(result);
}))
});
};