Question

我想在Firestore文档中存储图像路径的有序列表。图像通过元数据上载到存储，该元数据包含位置和链接到文档的标签。期望的图像数量是已知的。图像的上传几乎是同时完成的。

对，我是通过将图像路径列表存储为数组来实现的。简而言之：上载图像，使用事务读取文档，更改阵列并再次保存。交易永远不会失败，但有时在上传另一张图片后，数组项会再次消失。

我的两个问题是：对于此问题，数组是NoSql数据库中的最佳结构吗？尽管交易，数组项为何会消失？

export const addImageToTag = functions.storage.object().onFinalize(async (object) => {
    try {
        const tag = object.metadata.Tag;
        const position = object.metadata.Position;

        const tagRef = db.collection(COLLECTION_TAGS).doc(tag)
        const tagSnapshot = await db.runTransaction(t => t.get(tagRef));

        const images = tagSnapshot.data().images;
        images[position] = object.name;

        let uploadCount = 0;
        for (let i = 0; i < tagSnapshot.data().imageCount; i++) {
            if (images[i].length > 0) {
                uploadCount++;
            } else {
                break;
            }
        }

        let state;
        if (tagSnapshot.data().imageCount === uploadCount) {
            state = STATE_ACTIVE;
        } else {
            state = STATE_UPLOADING;
        }

        await tagSnapshot.ref.update({
            images: images,
            state: state
        });

        console.log('Image ', position, ' of tag ', tag, 'added')
    } catch (error) {
        console.error('Call failed: ', error)
    }
});

Answer 1

回答了第二个问题，实际上将代码放在事务块中就可以了。我已经读过使用tagSnapshot.ref引用标签文档就足够了，这是错误的。

export const addImageToTag = functions.storage.object().onFinalize(async (object) => {
    try {
        const tag = object.metadata.Tag;
        const position = object.metadata.Position;
        const tagRef = db.collection(COLLECTION_TAGS).doc(tag)

        await db.runTransaction(async transaction => {
            const tagSnapshot = await transaction.get(tagRef)

            const images = tagSnapshot.data().images;
            images[position] = object.name;

            let uploadCount = 0;
            for (let i = 0; i < tagSnapshot.data().imageCount; i++) {
                if (images[i].length > 0) {
                    uploadCount++;
                } else {
                    break;
                }
            }

            let state;
            if (tagSnapshot.data().imageCount === uploadCount) {
                state = STATE_ACTIVE;
            } else {
                state = STATE_UPLOADING;
            }

            transaction.update(tagRef, {
                images: images,
                state: state
            });

            if (state === STATE_ACTIVE) {
                console.log('All images of tag ', tag, ' were succesfully added')
            }
            });
    } catch (error) {
        console.error('Call failed: ', error)
    }
});

交易不会失败，但字段输入错误

1 个答案: