使用 TypeScript 反應選擇異步加載選項

Question

我正在將現有的 React 應用程序轉換為 typescript，我無法讓react-select async loadOptions正確解析為 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,
    }
}

錯誤是

    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

我不明白我需要在哪里聲明loadOptions的返回類型才能按預期工作。

Answer 1

如果這是您的loadOptions function 的實際代碼，那么它有幾個問題：

• 它不返回任何有意義的值（它返回undefined ，並且考慮到它具有返回類型Promise<void>的async ）
• 它沒有副作用

從實際的角度來看，它根本沒有任何用處，只是丟棄了響應數據。

---

要解決此問題，您可以采用以下方法之一：

1. 返回有用的東西。 然后你必須注釋 function 的返回類型：

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. 或執行副作用：

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