如何确保一个异步功能在另一个异步功能在 NodeJS 中启动之前完成？

Question

我是新手，可能会遗漏一些琐碎的事情。

public async RunWorkFlow() {
    const zipFile = await DownloadZipFile(123, `abc`);
    await UnzipZippedArtifacts(zipFile);
}

当我尝试上述操作时，有时 unzip 方法会在下载完成之前启动，并导致尝试解压缩损坏的（半下载）文件。 DownloadZipFile 和 UnzipZippedArtifacts 都是异步方法，我想确保 DownloadZipFile 在 UnzipZippedArtifacts 开始之前完成。

解压的时候报错

Error: Corrupted zip: can't find end of central directory表示文件没有正确下载。

---

    private async DownloadZipFile(buildId: number, projectName: string) : Promise<string>
    {
        const buildApi = await this.api.getBuildApi();
        const artifactDetails = await buildApi.getArtifacts(buildId, projectName);
        const localZipFileName = buildId.toString() + `_` + artifactDetails[0]?.name + `_` + Date.now() + ".zip";
        const artifactStream = await buildApi.getArtifactContentZip(
            buildId, 
            artifactDetails[0]?.name, 
            projectName);

        const localZipFileStream = fs.createWriteStream(localZipFileName);
        await artifactStream
            .pipe(localZipFileStream)
            .on(`finish`, () => {
                localZipFileStream.close();
                this.logger.I(`Artifact zip file was download successfully for buildId ${buildId} in the project ${projectName}, filename is ${localZipFileName}`);                
            });
        
        return localZipFileName;
    }

Answer 1

artifactStream.pipe(localZipFileStream).on(...) 没有返回 Promise，所以await-ing 它没有意义。它只注册一个回调（on 中的第二个参数）以在“完成”事件发生时调用。

为了从 DownloadZipFile 返回 Promise，您需要将 artifactStream.pipe(localZipFileStream).on(...) 包装在 Promise 中，然后在调用回调函数时解决：

private async DownloadZipFile(buildId: number, projectName: string) : Promise < string >
{
    const buildApi = await this.api.getBuildApi();
    const artifactDetails = await buildApi.getArtifacts(buildId, projectName);
    const localZipFileName = buildId.toString() + `_` + artifactDetails[0]?.name + `_` + Date.now() + ".zip";
    const artifactStream = await buildApi.getArtifactContentZip(
        buildId,
        artifactDetails[0]?.name,
        projectName);

    const localZipFileStream = fs.createWriteStream(localZipFileName);
    return new Promise(function (resolve, reject) {
        // resolve with location of saved file
        artifactStream
            .pipe(localZipFileStream)
            .on('finish', () => {
                localZipFileStream.close();
                this.logger.I(`Artifact zip file was download successfully for buildId ${buildId} in the project ${projectName}, filename is ${localZipFileName} `);

                resolve(localZipFileStream);
            });

    })
}