Sequelize correctly executing multiple creates + updates

Question

I have a cron job that scrapes a list of items on a website and then inserts or updates records in a database. When I scrape the page, I want to create records for new ones that haven't been created yet, otherwise update any existing ones. Currently I'm doing something like this:

// pretend there is a "Widget" model defined

function createOrUpdateWidget(widgetConfig) {
    return Widget.find(widgetConfig.id)
        .then(function(widget) {
            if (widget === null) {
                return Widget.create(widgetConfig);
            }
            else {
                widget.updateAttributes(widgetConfig);
            }
        });
}

function createOrUpdateWidgets(widgetConfigObjects) {
    var promises = [];

    widgetConfigObjects.forEach(function(widgetConfig) {
        promises.push(createOrUpdateWidget(widgetConfig));
    });

    return Sequelize.Promise.all(promises);
}


createOrUpdateWidgets([...])
    .done(function() {
        console.log('Done!');
    });

This seems to work fine, but I'm not sure if I'm doing this "correctly" or not. Do all promises that perform DB interactions need to run serially, or is how I have them defined ok? Is there a better way to do this kind of thing?

Answer 1

What you're doing is pretty idiomatic and perfectly fine, the only room for improvement is to utilize the fact Sequelize uses Bluebird for promises so you get .map for free, which lets you convert:

function createOrUpdateWidgets(widgetConfigObjects) {
    var promises = [];

    widgetConfigObjects.forEach(function(widgetConfig) {
        promises.push(createOrUpdateWidget(widgetConfig));
    });

    return Sequelize.Promise.all(promises);
}

Into:

function createOrUpdateWidgets(widgetConfigObjects) {
    return Sequelize.Promise.map(widgetConfig, createOrUpdateWidget)
}

Other than that minor improvement - you're chaining promises correctly and seem to have the correct hang of it.