javascript - 只返回最里面的promise的catch并处理其他的

Question

我有以下情况:

savePicture(newPicture, fileData){
    return compressionUtil.makePictureAndThumbnail(newPicture).then((data) => {
        let writeBig = fsUtil.writeFileToDisk(pictureFileName, data[0])
        let writeSmall = fsUtil.writeFileToDisk(thumbnailFileName, data[1])

        return Promise.all([writeBig, writeSmall]).then(() => {
            let picToSave = {
                uploaderUsername: fileData.username,
                directory: fileDirectory,
                fileName: fileName,
                tags: fileData.tags,
                description: fileData.description,
                droneTaken: fileData.droneTaken,
                isGenuine: isGenuine,
                metadata: metadata
            }
            return Picture.create(picToSave)
        })
    })
}

我想做的是处理 compressionUtil.makePictureAndThumbnail() 和 Promise.all([writeBig, writeSmall]) 可能被拒绝的情况，如下所示

savePicture(newPicture, fileData){
    return compressionUtil.makePictureAndThumbnail(newPicture).then((data) => {
        let writeBig = fsUtil.writeFileToDisk(pictureFileName, data[0])
        let writeSmall = fsUtil.writeFileToDisk(thumbnailFileName, data[1])

        return Promise.all([writeBig, writeSmall]).then(() => {
            let picToSave = {
                uploaderUsername: fileData.username,
                directory: fileDirectory,
                fileName: fileName,
                tags: fileData.tags,
                description: fileData.description,
                droneTaken: fileData.droneTaken,
                isGenuine: isGenuine,
                metadata: metadata
            }
            return Picture.create(picToSave)
        }).catch((err)=>{/*Handle promise.all error here*/})
    }).catch((err)=>{/*Handle makePictureAndThumbnail error here*/})
}

但同时使 savePicture() 仅返回 Picture.create() 的 Promise .then() 和 .catch()。

我想到的是将所有内容包装在一个巨大的新 Promise((resolve,reject)=>{}) 中，但这可能是一种糟糕的做法。

对此的意见表示赞赏。谢谢。

Answer 1

wrapping it all in a giant new Promise((resolve,reject)=>{}) is probably a terrible practice.

是的indeed it is !

要仅处理来自 Promise 的拒绝，而不是来自 then 履行回调，您可以 use .then(…, …) instead of .then(…).catch(…) :

savePicture(newPicture, fileData){
    return compressionUtil.makePictureAndThumbnail(newPicture).then((data) => {
        …
        return …
    }, err => {
//   ^ no `catch`
        /* Handle makePictureAndThumbnail error here */
    });
}

同样，

return Promise.all([writeBig, writeSmall]).then(() => {
    let picToSave = { … }
    return Picture.create(picToSave);
}).catch(err => {
    /* Handle all errors from writeBig, writeSmall and create */
});

return Promise.all([writeBig, writeSmall]).then(() => {
    let picToSave = { … }
    return Picture.create(picToSave).catch(err => {
        /* Handle errors from create */
    });
}, err => {
    /* Handle all errors from writeBig and writeSmall */
});