Appending query parameters to URI's in Vapor

URI+Helpers.swift

extension URI {
    public func appendingQueryParameters(_ parameters: [String: String]) -> URI {
        let allParameters = mergeParameters(queryParameters(fromQuery: query), rhs: parameters)
        let newQuery = toQuery(parameters: allParameters)

        return URI(scheme: scheme, userInfo: userInfo, hostname: hostname, port: port, path: path,
                   query: newQuery, fragment: fragment)
    }

    private func toQuery(parameters: [String: String]) -> String {
        let joined = parameters.reduce("", { result, next in
            return result + next.0 + "=" + next.1 + "&"
        })

        return String(joined[joined.startIndex..<joined.index(before: joined.endIndex)])
    }

    private func queryParameters(fromQuery query: String?) -> [String: String] {
        var params = [String: String]()
        guard let query = query else { return params }

        let comps = query.components(separatedBy: "&").reversed()
        comps.forEach { str in
            let expr = str.components(separatedBy: "=")
            params[expr[0]] = expr[1]
        }

        return params
    }

    private func mergeParameters(_ lhs: [String: String], rhs: [String: String]) -> [String: String] {
        var res = lhs

        for (k, v) in rhs {
            res[k] = v
        }

        return res
    }
}

Nice 👍

Saw this on twitter :-)

How does vapor handle arrays in query strings? This varies a lot between languages/frameworks, ie. node/express: http://httpbin.org/get?something=1&something=2

I's totally legal to have the same query key multiple times, golang uses something like [string: [string]] for the parameter representation for this reason: https://golang.org/pkg/net/url/#ParseQuery

Also you should probably encode keys and values, ie. https://developer.apple.com/documentation/foundation/nsstring/1411946-addingpercentencoding