B4J Tutorial [BANano] (v7) New object BANanoRouter

BANanoRouter is a full blown Router with paths that will be standard included in the next release of BANano. It allows you to better organize your code in a PWA/SPA WebApp. It is based on the Navigo project, tuned for B4J.

What is a Javascript Router?
A Javascript router is a key component in many frontend frameworks (e.g. Angular, Vue, ...). It is the piece of software in charge to organize the states of the application, switching between different views. For example, the router will render the login screen initially, and when the login is successfull it will perform the transition to the user’s welcome screen.

So 'logically', you web app could be something like:
--- Page1
--- Page2
--- Page3

Every page will have its own path, with its own variables and query parameters. The router is build so the URL in the navigation bar of the browser does not change. However, it one can still call a certain page with certain parameters by entering it in the navigation bar if one wants to.

We can add a new 'page' from the menu:

'This class is router page template class
Sub Class_Globals
    Private BANano As BANano 'ignore
End Sub

'Initializes the object. You can add parameters to this method if needed.
Public Sub Initialize()
End Sub

' router path /testPage1
Sub BANano_RouterHandle(url As String, data As Map, params As Map)
    ' navigating to some other page
    ' Main.router.Navigate("/testPage2/carine/?id=10&lastName=Bailleul")
End Sub

Sub BANano_RouterLeaving() As Boolean
    Log("Do some checks...")
    Return True ' (Or False If the navigation from this page Is Not allowed)
End Sub

It contains two special methods:
BANano_RouterHandle(url As String, data As Map, params As Map)

In this method you can do all your nice BANano stuff (like loading a Layout, getting data from your database etc)

The second method is:
BANano_RouterLeaving() As Boolean

This method is optional, and allows you to e.g. do some checks (is every field filled in?) before someone can leave the page and navigate to another one. If it returns True then it will go further, if False it will not.

Setting Up your routes:
Add a BANanoRouter to the Globals_Class of your Main:
Public router As BANanoRouter

In BANano_Ready():

1. Initialize the router
rootPath: the root path of your application. For example, if you are hosting the application at https://site.com/my/project you have to specify the following:
matchAll: default false, meaning that when a match is found the router stops resolving other routes. If set true, it will continue searching for other matches
e.g. Router.AddRoute("/foo/:id/?", "FooClass") matches "/foo/20/save" and also "/foo/20"

2. Now we can add our routes, for example:
router.AddRoute("/testPage1", "Page1", Array("Something extra")) ' here our initalize method in our page requires an extra parameter
router.AddRoute("/testPage2/:name", "Page2", Null) ' e.g. handle /testPage2/carine (carine will be in the Data map in BANano_RouterHandle of Page2)
router.AddRoute("/testPage3/:name/test", "Page3", Null) ' e.g. handles /testPage2/alain/test,  /testPage2/jos/test (alain or jos will be in the Data map in BANano_RouterHandle of Page3)

Some more advanced examples of paths:
Router.AddRoute(":page", "FooClass")
 - matches "/about-page"

Router.AddRoute("/foo/*", "FooClass")
 - matches "/foo/a/b/c"
 Router.AddRoute("*", "FooClass")
  - matches "/foo/bar/moo"
Router.AddRoute("/foo/:id/?", "FooClass")
 - matches "/foo/20/save" and also "/foo/20"

3. A special one can be added if there is no match found for the path:
router.NotFound("NotFound", Null)

4. And finally, we start our router, going to our first page:

Navigating between pages:
1. by code
Main.router.Navigate("/testPage2/carine/?id=10&lastName=Bailleul") ' will go to the Page2 class, with the variable "name" set to carine and the parameters id=10 and lastName="Bailleul"
Main.router.Navigate("/testPage3/jos/test") ' will go to the Page3 class with the variable "name" set to jos
Main.router.Navigate("/testPage4") ' will e.g. go to the NotFound class because it does not exist
So, although you internally change to another url, the text in the Navigation Bar in the browser will still be https://mydomain.com

2. by entering an url in the Browsers Navigation Bar

The router does use a hash system (#), so by just entering your path with the prefix /#/, it will be handled by the router.

Example will do exactly the same as the first example here above:

Removing a Route:
Just call RemoveRoute with the original path you used to add it.

This concludes the BANanoRouter tutorial.



Licensed User
Longtime User
Hi, for us not to confuse issues perhaps, let me ask a stupid question. Does this have any relation to "BANanoServer Browser/Server" navigation, handlers etc?
Is it necessary to use for BANanoServer apps too and if usable for such, how to implement for such cases? or perhaps because its not prefixed with "BANanoServer", its not necessary on BANanoServer.


Licensed User
Longtime User
They are complete different things. BANanoRouter is like the router you use in Vue. It routes your Pages completely on the client side (it is for "navigating' through your WebApp). You can use it in both stand-alone and BANanoServer WebApps, but I have not used that myself yet as for the project I am doing right now for a client I do not have to use a BANanoServer.