Best practives to work with complex tokens with Activities and Places (MVP)

[Andrew Uglev]

Hi! I read a lot about MVP, tokens, places but still newbie and need
an advise about complex token strategy.
For example I have a Book object (that has its activity, place, view).
The book can be shown, edited and commented by its ID. The token need
to be switched to smth like
#bookPlace:234/show
#bookPlace:234/edit
#bookPlace:234/comment

Switching to edit and add comment need to be done without reloading
object (I mean that something like getPlaceController().goTo(new
BookPlace("edit")) will reload the object)

To switch to "comment" state of book's view without reloading I'm
trying to use
History.newItem(History.getToken() + "/comment", false); // token
goes to #bookPlace:234/comment, the view displays comment input form

To properly display #bookPlace:234/comment token In the Book activity
constructor I need parse the token using something like:
String[] tokenPath = place.getPlaceName().split("/");
this.bookID = tokenPath[0];
this.action = tokenPath[1];

Are there some helper classes to parse and map complex tokens? Am I
right using History.newItem(History.getToken() + "/comment", false);
to add "actions" to token?

Any links on the best complex tokens implementation with Places and
Activities are welcome.

[l3dx]

I'm also very interested in this. Not necessarily "adding actions to
tokens", but I guess it relates. I'm wondering how I should work with
tokens built up from several parameters.

~ l3dx$

On Nov 18, 11:12 am, Andrew Uglev <andrew.ug...@gmail.com> wrote:
> Hi! I read a lot about MVP,tokens, places but still newbie and need

> an advise about complex token strategy.

> For example I have a Book object (that has its activity,place, view).

> The book can be shown, edited and commented by its ID. The token need
> to be switched to smth like
> #bookPlace:234/show
> #bookPlace:234/edit
> #bookPlace:234/comment
>
> Switching to edit and add comment need to be done without reloading
> object (I mean that something like  getPlaceController().goTo(new
> BookPlace("edit")) will reload the object)
>
> To switch to "comment" state of book's view without reloading I'm
> trying to use
> History.newItem(History.getToken() + "/comment", false);  // token
> goes to #bookPlace:234/comment, the view displays comment input form
>
> To properly display  #bookPlace:234/comment token In the Book activity
> constructor I need parse the token using something like:

> String[] tokenPath =place.getPlaceName().split("/");

> this.bookID = tokenPath[0];
> this.action = tokenPath[1];
>

> Are there some helper classes to parse and map complextokens? Am I

> right using  History.newItem(History.getToken() + "/comment", false);
> to add "actions" to token?
>

> Any links on the best complextokensimplementation with Places and
> Activities are welcome.

[Thomas Broyer]

On Friday, November 18, 2011 11:12:58 AM UTC+1, Andrew Uglev wrote:

Hi! I read a lot about MVP, tokens, places but still newbie and need
an advise about complex token strategy.
For example I have a Book object (that has its activity, place, view).
The book can be shown, edited and commented by its ID. The token need
to be switched to smth like
#bookPlace:234/show
#bookPlace:234/edit
#bookPlace:234/comment

Switching to edit and add comment need to be done without reloading
object (I mean that something like  getPlaceController().goTo(new
BookPlace("edit")) will reload the object)

It only reloads the object if your code reloads the object. It depends whether you reuse activities and/or switch their state "on the go", and whether you use some kind of caching for your objects.

You could, for instance, return the very same activity instance but switch the activity to an "edit" (or "comment", or "view") state depending on the place. I wouldn't do that because it adds state to the activity, which can lead to complex activities that are hard to test and to maintain.

Or you could simply use some caching for your objects, so that even if you start a new EditBookActivity you can use the same Book instance as the one you used second before in the ViewBookActivity, without reaching the server.

For my part, I'd reload the object from the server (to have the freshest possible data), until it's proved to be a performance issue that needs solving; and then only add some caching or use more complex activities (how about a BookActivity that "wraps" the previous ViewBookActivity, EditBookActivity and CommentBookActivity, to switch them –mimicking an ActivityManager, re. activities' lifecycle– easily while providing them a cached Book entity?)

That's what we're doing ATM, and we haven't heard any negative feedback about performance (actually, even if that was the case, we couldn't do much about it, because going from "view" to "edit" in our case involves making a "checkout" and a lock on the server-side: the entity is either in "view" or "edit" mode, which drives the UI; it's not just a UI choice).

 

To switch to "comment" state of book's view without reloading I'm
trying to use
History.newItem(History.getToken() + "/comment", false);  // token
goes to #bookPlace:234/comment, the view displays comment input form

To properly display  #bookPlace:234/comment token In the Book activity
constructor I need parse the token using something like:
String[] tokenPath = place.getPlaceName().split("/");
this.bookID = tokenPath[0];
this.action = tokenPath[1];

Are there some helper classes to parse and map complex tokens?

No, but the parsing should be done in a PlaceTokenizer, not in activities. Your BookPlace should have two fields: bookId and action, and its PlaceTokenizer builds a <bookId>/<action> token and similarly parses it. You activities just see a BookPlace with two fields.

That way, you can easily change your tokens at any time (e.g. switch <bookId>;action=<action> or <bookId>:<action> for instance), without changing anything in your activities, only the PlaceTokenizer responsible for the BookPlace. Separation of concerns FTW!

Apart from that, no, there's no helper class in GWT: you're free to use any kind of token you want, and you're responsible for parsing and serializing them to/from places.

 

Am I
right using  History.newItem(History.getToken() + "/comment", false);
to add "actions" to token?

No.

If you need to change place, use PlaceController.goTo.

If you don't want a new activity, have your ActivityManager return the very same instance; that way it won't be onStop()ed and start()ed again, but simply reused as is (it won't even be notified of the place change, listen to the PlaceChangeEvent from within your Activity if you need to).

If you don't want to reach your server to get an object from its ID, use a cache.

Using History.newItem that way, you're dependent upon your tokens' format, and if you have another ActivityManager that would need to be notified of the change (maybe you don' t have one right now, but you could have a need later on), it won't be.

PlaceController.goTo is the way to go here.