Understand how middleware works in Moleculer

Question

I understand Mix-ins are to extend a common functionality across services. But Im not able to understand how middleware works in molecular and what problems It could help me solve.

Answer 1

Check the documentation how middleware works in Moleculer framework: https://moleculer.services/docs/0.13/middlewares.html

With middlewares you can extend the framework functionality with your custom logic. Here is an example how a middleware looks like which extend service action handling:

const MyCustomMiddleware = {
    // Wrap local action handlers (legacy middleware handler)
    localAction(next, action) {
        return function(ctx) {
            // Change context properties or something
            return next(ctx)
                .then(res => {
                    // Do something with the response
                    return res;
                })
                .catch(err => {
                    // Handle error or throw further
                    throw err;
                });
        }
    }
};