Routing

Rafał Lorenz edited this page Jun 1, 2017 · 3 revisions

The router determines how to handle that request. GoRouter uses a routing tree. Once one branch of the tree matches, only routes inside that branch are considered, not any routes after that branch. When instantiating router, the root node of router tree is created.

Route types

  • Static /hello will match requests matching given route
  • Named /{name} will match requests matching given route scheme
  • Regexp /{name:[a-z]+} will match requests matching given route scheme and its regexp

Wildcards

The values of named parameter or regexp parameters are accessible via request context params, ok := gorouter.FromContext(req.Context()). You can get the value of a parameter either by its index in the slice, or by using the params.Value(name) method: {name} or /{name:[a-z]+} can be retrived by params.Value("name").

Defining Routes

A full route definition contain up to three parts:

  1. HTTP method under which route will be available
  2. The URL path route. This is matched against the URL passed to the router, and can contain named wildcard placeholders (e.g. :placeholders) to match dynamic parts in the URL.
  3. http.HandleFunc, which tells the router to handle matched requests to the router with handler. Take the following example:
router.GET("/hello/{name:r([a-z]+)go}", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
    params, _ := gorouter.FromContext(r.Context())
    fmt.Fprintf(w, "hello, %s!\n", params.Value("name"))
}))

In this case, the route is matched by /hello/rxxxxxgo for example, because the {name} wildcard matches the regular expression wildcard given (r([a-z]+)go). However, /hello/foo does not match, because "foo" fails the name wildcard. When using wildcards, these are returned in the map from request context. The part of the path that the wildcard matched (e.g. rxxxxxgo) is used as value.

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