I am using localforage which returns a promise for functions such as key() and length(). I am also using $http() which returns a promise for too but it includes a finally() function, which the other does not.
My services down the chain do not know whether localforage or $http makes the request so they all require the same promise structure (finally and then). Is there a way to add finally to the promises that do not already have it?
I have attempted to append $q.defer().promise.finally to my promises from localforage which did not work.
var promise = localforage.length();
promise.finally = $q.defer().promise.finally;
return promise;
Is there another way to achieve this?
If you want to "convert" one promise into another you can use their resolve method to resolve an inner promise (or to adopt the value of the promise). For $q you can use the resolve method here. So basically:
return $q.resolve(localforage.length());
There's also Promise.prototype.finally coming up soon, so you can scratch $q and use native Promise with a shim. All you got to do is literally use Promise instead of $q (literally).