等待函数完成，然后继续执行Gulp任务的其余部分

Question

我正在尝试构建一个依赖于包含连接信息的ftp.json文件的FTP gulp任务。此文件包含在.gitignore中，因此当开发人员克隆repo时，它不存在。我运行一个检查，看看他们是否设置了一个ftp.json，如果一个不存在，它会下载一个空白的。

我遇到的问题是，当它下载文件时，它也会抛出错误，结束任务。我希望有一些东西说“等待这个功能完成，然后继续执行剩下的任务”以防止错误发生。这是我目前的FTP任务：

// upload to FTP environment
gulp.task("ftp", function(callback) {
    // development FTP directory
    var ftpDirectory = dev;

    // production FTP directory (if --dist is passed)
    if (argv.dist) {
        ftpDirectory = dist;
    }

    // check if the FTP.json exists
    fs.exists("./ftp.json", function(exists) {
        // if it doesn't, download it
        if (!exists) {
            download("https://gist.githubusercontent.com/revxx14/a04f5ba7e00b267e71e2/raw/197fcf2478cc7ee77afaa4d200f908ccdccbc822/ftp.json")
                .pipe(gulp.dest("./"));
        }
    }); // should wait here, and only continue once the download completes.

    // read FTP credentials fromt ftp.json
    var host = json.read("./ftp.json").get("dev.host"),
        user = json.read("./ftp.json").get("dev.user"),
        pass = json.read("./ftp.json").get("dev.pass"),
        path = json.read("./ftp.json").get("dev.path");

    // read dist FTP credentials from ftp.json (if --dist is passed)
    if (argv.dist) {
        host = json.read("./ftp.json").get("dist.host"),
        user = json.read("./ftp.json").get("dist.user"),
        pass = json.read("./ftp.json").get("dist.pass"),
        path = json.read("./ftp.json").get("dist.path");
    }

    // reconfigure ftp.json if a field is empty or if --config is passed
    if (host === "" || user === "" || pass === "" || argv.config) {
        gulp.src("./ftp.json")
            .pipe(prompt.prompt([{
                // prompt for the hostname
                type: "input",
                name: "host",
                message: "host:",
                default: host,
            },
            {
                // prompt for the username
                type: "input",
                name: "user",
                message: "username:",
                default: user,
            },
            {
                // prompt for the password
                type: "password",
                name: "pass",
                message: "password:",
                default: pass,
            },
            {
                // prompt for the remote path
                type: "input",
                name: "path",
                message: "remote path:",
                default: path,
            }], function(res) {
                // open the ftp.json
                var file = json.read("./ftp.json");

                // set connection to dev
                var connection = "dev";

                // set connection to dist (if --dist is passed)
                if (argv.dist) {
                    connection = "dist";
                }

                // update the file contents
                file.set(connection + ".host", res.host);
                file.set(connection + ".user", res.user);
                file.set(connection + ".pass", res.pass);
                file.set(connection + ".path", res.path);

                // write the updated file contents
                file.writeSync();
            }));
    }

    // create the FTP connection
    var conn = ftp.create({
        host: host,
        user: user,
        pass: pass,
        path: path,
    })

    // upload the changed files
    return gulp.src(ftpDirectory + "/**/*")
        .pipe(conn.newer(path))
        .pipe(conn.dest(path));
})

我正在使用gulp-download来获取下载功能，如果这很重要的话。如果这意味着我可以让它发挥作用，我会很乐意转向别的东西。

Answer 1

好的，感谢@rmjoia，我想出了如何设置依赖项。这是我的最终任务集：

// initialize ftp.json
gulp.task("ftp-init", function(cb) {
    // check if the ftp.json exists
    fs.stat("./ftp.json", function (err, stats) {
        if (err != null) {
            // if it doesn't, create it
            fs.writeFile("./ftp.json", "{\"dev\": {\"host\": \"\",\"user\": \"\",\"pass\": \"\",\"path\": \"\"\},\"dist\": {\"host\": \"\",\"user\": \"\",\"pass\": \"\",\"path\": \"\"\}}", function (err) {
                cb(err);
            });
        } else {
            // otherwise return
            cb(err);
        }
    });
});

// configure FTP credentials in ftp.json, depends on ftp-init
gulp.task("ftp-config", ["ftp-init"], function(cb) {
    // read FTP credentials from ftp.json
    host = json.read("./ftp.json").get("dev.host"),
    user = json.read("./ftp.json").get("dev.user"),
    pass = json.read("./ftp.json").get("dev.pass"),
    path = json.read("./ftp.json").get("dev.path");

    // read dist FTP credentials from ftp.json (if --dist is passed)
    if (argv.dist) {
        host = json.read("./ftp.json").get("dist.host"),
        user = json.read("./ftp.json").get("dist.user"),
        pass = json.read("./ftp.json").get("dist.pass"),
        path = json.read("./ftp.json").get("dist.path");
    }

    if (host === "" || user === "" || pass === "" || argv.config) {
        // reconfigure ftp.json if a field is empty or if --config is passed
        gulp.src("./ftp.json")
            .pipe(prompt.prompt([{
                // prompt for the hostname
                type: "input",
                name: "host",
                message: "host:",
                default: host,
            },
            {
                // prompt for the username
                type: "input",
                name: "user",
                message: "username:",
                default: user,
            },
            {
                // prompt for the password
                type: "password",
                name: "pass",
                message: "password:",
                default: pass,
            },
            {
                // prompt for the remote path
                type: "input",
                name: "path",
                message: "remote path:",
                default: path,
            }], function(res) {
                // open the ftp.json
                var file = json.read("./ftp.json");

                // set connection to dev
                var connection = "dev";

                // set connection to dist (if --dist is passed)
                if (argv.dist) {
                    connection = "dist";
                }

                // update the file contents
                file.set(connection + ".host", res.host);
                file.set(connection + ".user", res.user);
                file.set(connection + ".pass", res.pass);
                file.set(connection + ".path", res.path);

                // write the updated file contents
                file.writeSync();

                cb(null);
            }));
    } else {
        // otherwise return
        cb(null);
    }
})

// upload to FTP environment
gulp.task("ftp-upload", ["ftp-config", "ftp-init"], function(cb) {
    // development FTP directory
    var ftpDirectory = dev;

    // production FTP directory (if --dist is passed)
    if (argv.dist) {
        ftpDirectory = dist;
    }

    // create the FTP connection
    var conn = ftp.create({
        host: host,
        user: user,
        pass: pass,
        path: path,
    })

    // upload the changed files
    return gulp.src(ftpDirectory + "/**/*")
        .pipe(conn.newer(path))
        .pipe(conn.dest(path));

    // return
    cb(null);
});

// combine FTP tasks
gulp.task("ftp", ["ftp-upload", "ftp-config", "ftp-init"]);

看起来有点荒谬复杂，但它确实有效，所以我现在很高兴。