Question

我正在尝试使用Sequalize ORM在数据库中创建新行。我收到了req.query.collections的一系列集合。对于每个集合，我需要创建一个新的userCollection。如果没有创建userCollection，我想用内部服务器错误（第41行）进行响应，否则返回带有新创建的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。当我检查数据库时，发现创建了userCollections，所以没有发生错误。

我知道为什么会这样：因为userCollection.build({ stuff }).save()返回了一个承诺。因此，当我尝试从userCollections语句中进行console.log .then()时，就像我应该的那样，我得到一个包含新创建的集合的数组。但是到那时，服务器已经响应了内部服务器错误。

这是我的功能代码：

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

感谢创建本教程的塞巴斯蒂安·肖邦（Sebastien Chopin）： https://codeburst.io/javascript-async-await-with-foreach-b6ba62bbf404

所以我添加了此功能：

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

我做的不是collections.forEach...(blah blah)（问题中发布的代码的第10行），而是：

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));
}

Node.js Sequalize在forEach循环中创建新行

1 个答案: