I guess you have to remember that Akka-HTTP originates from Spray - and so
those choices were likely already made. (I'm sure there is a fully
plausible performance threading reason that is beyond me too hehe).
Well I know how i'd do nesting in Java at least if its any help.
Implementing a custom directive is easy! And the requestContext which is
passed into every layer of your route (presumably its an implicit value in
scala?) can be extended and passed around with the additional info you
might need such as a slowly building list of string segment paths. You can
then signal that your at a leaf node of your tree by calling end or the
likes - and return a single Path with the full linear evaluation of that
point in the tree recursion.
So how I'd do it is implement my own directive called Segment maybe a
little like this:
public abstract class SegmentDirectives extends AllDirectives
public Route segment(String segment, Route inner) {
return this.mapRequestContext((innerCtx) -> {
//You could put some logic here and then do something - you can control the
RequestContext which gets passed to the child
//Hence you can control whether the lower level stuff get invokes or not
based on what the full path is
return new RequestContext(new
MySuperNewRequestContextWhichObviouslyImplementsRequestContextInterface(
innerCtx.delegate(), segment));
}
}
}
Your new RequestContext impl could then just keep a List<String> - that it made
available as a PathMatcher when you chose to 'finish' your tree like:
public Route endSegment(Route innerRoute){
return this.mapRequestContext(innerCtx-> {
if(innerCtx instanceof MySuperNewRequest.....){
return path(((MySuperNewRequest)innerCtx).getPathMatcherForBuiltPaths,
innerRoute);
}
})
}
Then simply do a route a little like:
segment("v1", { segment("orders", {end({whatever})}), segment("customers",
{end({whatever})}) }
Well obviously the 'this is how id do it' bit is a lie - I wouldn't do it.
I'd probably ask myself why I had hundreds of apis and wanted to list those
all in 1 mega file using a nested tree that either presumably is going to
flip flop all over the classes in the project, or move further and further
to the right of the screen as it becomes deeper.
I know the reality of software development is generally you get stuck with
tough situations like that from historical decisions so fair enough if its
really required. At the end of the day though - even writing 300 linear
apis reusing PathMatcher variables preconfigured to do most of common
situations can end up the same kind of amount of code as the nest
equivalent. I know it doesn't feel like it initially but keep faith! :)
For context our largest service has around 10 classes which implement Route
- each class probably has about 6 apis in it, and all of these are pulled
in using Guice multi-binding - meaning I end up with 10 beautifully crafted
readable classes called things like V1OrdersRoute, V2OrdersRoute,
V1CustomersRoute and then all have the same OAUTH2 authentication
protections and error logging applied when the multi-binding is injected
and connected up to the Route flow on the HTTP server ensuring no-one goes
without good security protocols or basic access logging. In my HTTPServer I
simply put @Inject private MultiBinder<Route> allMyRoutes and attach it
into a tree with the above stated requirements.
On Friday, 17 March 2017 11:25:09 UTC, Alan Burlison wrote:
>
> I'm sure I must be missing something here because I can't believe path
> matching in Akka HTTP could be broken in the way it seems to be, because
> it would be unusable for anything other than toy applications if it was:
>
> I'm composing route handing from a top-level handler and sub-handlers
> like this:
>
> pathPrefix("root") {
> concat(
> pathPrefix("service1") { service1.route },
> pathPrefix("service2") { service2.route }
> )
> }
>
> where service1.route etc returns the sub-route for the associated
> sub-tree. That works fine with a path of say "/root/service1", but it
> *also* matches "/rootnotroot/service1", because pathPrefix() just
> matches any arbitrary string prefix and not a full path segment. And if
> I use path() instead of pathPrefix() it tries to match the entire
> remaining path. What I'm looking for is something along the lines of
> segment() where that fully matches just the next path segment and leaves
> the remaining path to be matched by inner routes, but there doesn't seem
> to be such a thing.
>
> What am I missing?
>
> Thanks,
>
> --
> Alan Burlison
> --
>
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