用loadOptions选择异步TypeScript

Question

我正在将现有的react应用程序转换为类型记录，而且我很难让反应-选择异步loadOptions正确地解析为类型记录。

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,
    }
}

错误是

    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

我不明白在哪里需要声明返回类型以使loadOptions按预期工作。

Answer 1

如果这是您的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，并考虑到async它有返回类型Promise<void>)
• 它没有副作用

从实际的角度来看，它没有任何用处，只是丢弃响应数据。

要解决以下问题，您可以采取下列方法之一：

1. 还一些有用的东西。然后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)
            })
        });

1. 或执行副作用：

// 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);
        }))
    });
};