打字稿：無法將json檔案內容加載到陣列中

我需要使用檔案結構 api.json 從 json 檔案（api.json）加載我的 apikey：

{
"service1": ["apikey1", "apikey2"],
"service2": ["apikey1", "apikey2"],
}

我有一個描述鍵和值的類：

class ApiKey {
   constructor(apiName: String, apiKeys: Array<String>)
}

我有一個類，它將所有鍵從檔案加載到陣列：

//read file async: https://stackoverflow.com/questions/46867517/how-to-read-file-with-async-await-properly
    import { readFile } from 'fs'
    import { promisify } from 'util'
    import { join } from 'path'

    export class ApikeysService {

    constructor(private apiKeys: Array<ApiKey> = new Array<ApiKey>()) {
        this.loadKeys()
    }

    public loadKeys () {
        const filePath      = join(__dirname, "../../../", "api.json");
        const readfile      = promisify(readFile);
        const result        = readfile(filePath, "utf8")
                                .then(content => JSON.parse(content))
                                .then(result => {
                                    Object.keys(result).forEach(key => {
                                        this.apikeys.push(new ApiKey(key, result[key]))
                                    })
                                })
        
    }

    public getKeyFor(name: String) {
        return this.keyCounters.find(x => x.keyname == name).apiKeys
    }

}

我的測驗：

describe('should load api keys', () => { 
    it("should load apikeys from file", async () => {
         const service = new ApikeysService ()
         it("should load api keys for service1", () => {
    

         expect(service.getKeyFor("service1")[0]).toEqual("apikey1")
         expect(service.getKeyFor("service1")[1]).toEqual("apikey2")

    })
})

測驗結果：

expect(received).toEqual(expected) // 深度相等

>     Expected: "apikey1"
>     Received: undefined

我嘗試了很多不同的方法來將內容從檔案加載到類中的陣列（也是異步的），但它不會作業

uj5u.com熱心網友回復：

您正在建構式中觸發異步函式，然后直接檢查結果 - 您沒有機會解決承諾。它不是同步的。

return result從loadKeys并確保等待它，或者將其更改為同步，使用readFileSync.

示例 1

export class ApikeysService {
    constructor(private apiKeys: Array<ApiKey> = new Array<ApiKey>()) {
        this.loadKeys()
    }

    public loadKeys () {
        const filePath      = join(__dirname, "../../../", "api.json");
        const readfile      = promisify(readFile);
        const content       = JSON.parse(readFileSync(filePath, "utf8"));

        Object.keys(result).forEach(key => {
            this.apikeys.push(new ApiKey(key, result[key]))
        })        
    }

    public getKeyFor(name: String) {
        return this.keyCounters.find(x => x.keyname == name).apiKeys
    }
}

示例 2

export class ApikeysService {
    constructor(private apiKeys: Array<ApiKey> = new Array<ApiKey>()) {
        // this.loadKeys()
    }

    public loadKeys () {
        const filePath      = join(__dirname, "../../../", "api.json");
        const readfile      = promisify(readFile);
        const result        = readfile(filePath, "utf8")
                                .then(content => JSON.parse(content))
                                .then(result => {
                                    Object.keys(result).forEach(key => {
                                        this.apikeys.push(new ApiKey(key, result[key]))
                                    })
                                })
        return result;   
    }

    public getKeyFor(name: String) {
        return this.keyCounters.find(x => x.keyname == name).apiKeys
    }
}

describe('should load api keys', () => { 
    it("should load apikeys from file", async () => {
        const service = new ApikeysService ()
        await service.loadKeys();

        it("should load api keys for service1", () => {
            expect(service.getKeyFor("service1")[0]).toEqual("apikey1")
            expect(service.getKeyFor("service1")[1]).toEqual("apikey2")
        })
    })
})

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