How to retrieve values from a context in Vapor? - vapor

Question

In Vapor, specifically in the class for a custom Leaf tag, how can you retrieve values stored in a context?
I'm trying to implement a tag that takes a string and a path, and renders a link unless the path is the current page, so, for example, #navElement("About Us", "/about") will produce a link to the site's about page on every page except the about page itself. On that page, it should display the text without a link on it.
I don't want to have to pass the current path to the tag every time I use it, so I've stored the request's path in the context, roughly like this (checks omitted):
drop.get(":page"){ request in
return try drop.view.make(thePage, ["path": request.uri.path])
}
I can use #(path) in a template and see the path I expect.
My custom tag is derived from Tag, and its run method receives the context as an argument, and I can see the stored value in there in the debugger – but how do I get at it? The get method in the Context class, which seems to do this, is internal, so I can't use it. There is a comment that says subscripts are to be done, and I assume that this will ultimately be the way to extract values from the context, but in the meantime, is there any way to retrieve them?

Answer 1

Just make the current path one of the arguments to your tag.
Droplet route:
drop.get(":page") { request in
return try drop.view.make(thePage, ["currentPath": request.uri.path])
}
In template:
#navElement("About Us", "/about", currentPath)
Tag:
class NavElement: Tag {
let name = "navElement"
public func run(stem: Stem, context: LeafContext, tagTemplate: TagTemplate, arguments: [Argument]) throws -> Node? {
guard
let linkText = arguments[0].value?.string,
let linkPath = arguments[1].value?.string,
let currentPath = arguments[2].value?.string
else { return nil }
if linkPath == currentPath {
return Node("We are at \(currentPath)")
} else {
return Node("Link \(linkText) to \(linkPath)")
}
}
}
Edit:
I have spoken to the developers of Vapor, and they do not intend to open up access to Context's contents publicly. However, since the queue: List<Node>() is public, you can just copy the get() function into your own extension and then you'll be able to do as you wanted.