Node.js Sequelize 在 forEach 循环中创建新行

Question

我正在尝试使用 Sequalize ORM 在数据库中创建新行。我从 req.query.collections 收到一组集合。对于每个集合，我需要创建一个新的 userCollection 。如果没有创建 userCollection ，我想以内部服务器错误(第 41 行)进行响应，否则返回一个包含新创建的 userCollections 的对象数组。

问题是，当我从 Postman 发出测试请求时，我不断收到内部服务器错误。当我检查我的数据库时，我看到那些 userCollections 已创建，因此没有发生错误。

我知道为什么会发生这种情况:因为 userCollection.build({ stuff }).save() 返回一个 promise 。因此，当我尝试从 userCollections 语句中 console.log .then() 时，我得到一个包含新创建集合的数组，就像我应该的那样。但是到那时服务器已经响应内部服务器错误。

这是我的函数代码:

exports.addCollections = async (req, res, next) => {
    const libraryId = req.params.libraryId;
    const collections = req.query.collections;

    if (!collections)
        next(Boom.forbidden());

    const userCollections = [];

    collections.forEach(async (collectionId, index) => {
        const collection = await Collection.findByPk(collectionId);

        if (!collection)
            return next(Boom.notFound());

        userCollection.build({
            user_id: req.user.id,
            library_id: libraryId,
            public_collection_id: collection.id,
            title: collection.title,
            description: collection.description
        })
            .save()
            .then(newUserCollection => {
                userCollections.push(newUserCollection.get({ plain: true }));

                // should be printed first, but comes second
                // prints out the array with newly created record
                console.log(userCollections);
            })
            .catch(error => {
                console.log(error);
            });
    });

    // should be printed second, but comes first
    // prints out empty array
    console.log(userCollections);

    if (userCollections.length === 0) {
        next(Boom.internal());
    }

    res.json(userCollections);
}

Answer 1

发布解决方案

感谢创建本教程的 Sebastien Chopin:
https://codeburst.io/javascript-async-await-with-foreach-b6ba62bbf404

所以我添加了这个功能:

const asyncForEach = async (array, callback) => {
    for (let index = 0; index < array.length; index++) {
        await callback(array[index], index, array)
    }
}

而不是 collections.forEach...(blah blah) (问题中发布的代码的第 10 行)，我这样做:

try {
    await asyncForEach(collections, async (collectionId, index) => {
        const collection = await Collection.findByPk(collectionId);

        if (!collection)
            return next(Boom.notFound());

        userCollection.build({
            user_id: req.user.id,
            library_id: libraryId,
            public_collection_id: collection.id,
            title: collection.title,
            description: collection.description
        })
            .save()
            .then(newUserCollection => {
                userCollections.push(newUserCollection.get({ plain: true }));
                console.log(userCollections);
            })
            .catch(error => {
                console.log(error);
            });
    })
} catch (err) {
    return next(Boom.internal(err.message));
}