I've encountered a situation where I have multiple functions that return promises, and I want to generalize them. As a result, I've structured them in the following way:
function checkWebpageForReference(data){
//code to check webpage for reference
}
function takeScreenshot(data){
//code to take screenshot of webpage
}
function uploadReferencePictureToS3(data){
//code to upload picture to S3
}
function saveNewReferenceToDb(data){
//code to save new Reference to database
}
function readFile(data){
//code to read file from file structure
}
function deleteFile(data){
//code to delete file from file structure
}
In each function, I resolve data because I anticipate having numerous similar functions that need to be chained together without specific order:
readfile(somedata)
.then(upload)
.then(delete)
.then(save)
//etc
This chaining method works well until I encounter situations requiring Promise.all:
Promise.all([
referenceTools.checkWebpageForReference(req.body),
referenceTools.takeScreenshot(req.body)
])
.then(function(results){
utils.readFile(results[1])
.then(referenceTools.uploadReferencePictureToS3)
.then(utils.deleteFile)
.then(referenceTools.saveNewReferenceToDb)
.then(function(data){
res.json(data.newReference);
})
.catch(function(err){
utils.errorHandler(err);
res.send("Internal error occurred. Please try again later.");
});
})
.catch(function(err){
utils.errorHandler(err);
res.send("Internal error occurred. Please try again later.");
});
My challenge arises when using Promise.all().then(upload) due to the combined resolutions from both checkWebpageForReference and takeScreenshot. In essence, within readFile, accessing data fields becomes difficult as the resulting promise is an array like [data, data].
Is there a recommended pattern or approach I could follow to simplify this process while ensuring modularity and adequate data transmission between promises?