Reverse url

[saml]

Needs a function that behaves as follows:

e.Get("/users/:id", getUser)
e.URL(getUser, "123")
// => "/users/123"

[zbindenren]

+1

[patrickdappollonio]

+1! This, while it looks like nothing, could make a huge difference maintaining big websites, and you can be confident that any route change you won't need to go through your entire code base to see what to change...

[fundon]

+1 url path helper

[emilgpa]

+1

[vishr]

I would like to know some practical example of this case. Please point me to some frameworks API supporting it.

[saml]

One practical use case is when I want to write a RESTful API with hyperlinks.
For example, using HAL , I would want resource representation to include various links to other states client can go from here.

Of course I can write methods for calculating urls for various resources. But it involves duplicate work. If I change route, I need to change my relevant UrlFor method as well.

Some routing frameworks that support reverse url:

• http://www.gorillatoolkit.org/pkg/mux#Route.URL
• http://flask.pocoo.org/docs/0.10/api/#flask.url_for
• https://playframework.com/documentation/2.3.x/ScalaRouting#Reverse-routing

Play one is interesting cause routes are defined in DSL and generates reverse route functions during compilation.

If routes are specified using URI Template, it's known to be reversible: https://github.com/jtacoma/uritemplates (see Expand).

[patrickdappollonio]

Here's another framework who has this functionality: http://laravel.com/docs/5.0/routing#named-routes

[vanng822]

It is convenient to bind this kind of method to request/router but there is a drawback when you have small number applications/services which need those urls. We had some extra implement/workaround to make thing work. I tried to fix it just providing a route manager https://github.com/vanng822/r2router/blob/master/example/routemanager.go
Maybe something?

[vishr]

@saml, @patrickdappollonio, @fundon: Let me know how it looks. Further, as I have a map of handler and url, do you think an API to return it will be helpful?

https://github.com/labstack/echo/blob/master/echo_test.go#L237

[newoga]

@vishr, Just submitted a pull request with a couple more tests. It seems like this has some issues when the handlers are paired with a group. Was the API meant to work this way?

[newoga]

Also, a couple of other suggestions...

1. Maybe rather than the URI() method accepting a ...string, how about it accepts ...interface{}

This way we can pass any type of value and determine how it should become a string. For example, we should be able to determine if the interface that was passes implements the Stringer interface. That way if you pass a UUID object to to the reverse routing method, it could still work.

1. Also, It might be nice to support sending a map to the reverse route method, such as...

e.Get("/users/:id/:files:/fid", getFile)
e.URL(getUser, map[string]interface{}{
  "id": "1", // string works
  "fid": 2, // int works
  "other_id": guid, // as long as it implements `String()` it would work
})

[newoga]

Okay, I closed my original pull request and created a new one #37, this one actually fixes the issue when you call the URI() method on the right instance of *Echo.

That being said, I think it would be useful to maintain some kind of link between instances of *Echo and child *Echo when created by calling Group(). Not quite sure what the right API would be for this, but it would be nice if I could call the root *Echo.URI() and it would know how to create the URI for all handler on itself and its child *Echo.

To test this, we would have to add back the two checks in the TestEchoURL method:

    e := New()
    getGroups := func(*Context) {}
    getGroup := func(*Context) {}

    eg := e.Group("/groups")
        eg.Get("", getGroups)
    eg.Get("/:id", getGroup)

    // These two tests would currently fail
    if e.URI(getGroups) != "/groups" {
        t.Error("uri should be /groups")
    }
    if e.URI(getGroup, "1") != "/groups/1" {
        t.Error("uri should be /groups/1")
    }

   // These two tests currently pass
    if eg.URI(getGroups) != "/groups" {
        t.Error("uri should be /groups")
    }
    if eg.URI(getGroup, "1") != "/groups/1" {
        t.Error("uri should be /groups/1")
    }

In my opinion, ideally we can have it setup so all 4 pass.