Caches are notoriously difficult to implement correctly. I’ve done it a few times for work-related projects and I think each time there was at least one problem.
Ideally I would like a solution that would use the cache almost as a side effect or something that you don’t explicitly code against.
For example, lets say you had a http interface for your program called FooService and it implemented a few methods for getting data.
class FooService {
getFoo1();
getFoo2();
//etc
}Then I would like to cache the get methods and not change FooService. I was thinking something like this would be cool: LocalCache<FooService> and that would wrap each of the get methods automatically.
Well, that might work out, but I have to learn about Typescript’s type system a little bit more.
For starters I wrote this ionic-http-cache. This is basically a wrapper around your get calls. Some more work will need to be done to account for needed http headers and/or params.
The cache key is the url and you can specify different expire times for each key.
You can also invalidate the entire cache or just the data for a key.
And it returns Observables.
It also uses Ionic storage for the backing. Another good this is you don’t to change the the service code, but will have to change each client that uses the cache.
So this is a really simple cache, and it needs to be date to handle the http headers and params. I’ll do that in a following post, but for the time being, this will work.