An elegant USSD router in go
A router sits between the routing engine and the end function. The job of a router is to create requests from the incoming web request and provide session management.
The routing engine already takes care of managing the different states that the end application might have.
Additional routers can be found in routers.
The router must implement the grouter.Router interface and provide implementations
for grouter.UssdRequest, and grouter.UssdSession interfaces.
The library also supports template usage with custom function bindings.
go get github.com/SharkFourSix/grouterExample grouter_test.go
package grouter_test
import (
"net/http"
"os"
"testing"
"text/template"
"github.com/SharkFourSix/grouter"
"github.com/SharkFourSix/grouter/routers/at" // include africastalking implementation
)
func TestMain(t *testing.T) {
e, err := grouter.NewRouterEngine(
grouter.DebugMode,
grouter.WithRouter(at.RouterName),
grouter.WithTemplateFS(os.DirFS("./testdata/templates"), ".", template.FuncMap{}),
)
if err != nil {
t.Fatal(err)
return
}
e.MenuOptions(
grouter.NewMenuOption("", welcomeScreen, "welcomeScreen",
grouter.NewMenuOption("1", showAccount, "accountMenu",
grouter.NewMenuOption("1", accountBalance, "accountBalance",
grouter.NewMenuOption("#", showAccount, "accountMenu"),
),
grouter.NewMenuOption("2", miniStatement, "miniStatement",
grouter.NewMenuOption("#", showAccount, "accountMenu"),
),
grouter.NewMenuOption("3", makeTransfer, "makeTransfer",
grouter.NewMenuOption("#", showAccount, "accountMenu"),
),
grouter.NewMenuOption("#", welcomeScreen, "welcomeScreen"),
),
grouter.NewMenuOption("#", endSession, "endSession"),
),
)
http.Handle("/ussd", e)
http.ListenAndServe(":1234", nil)
}
type transferStep int
const (
ReadAccount transferStep = iota
ReadAmount
ConfirmTransfer
)
func makeTransfer(req grouter.UssdRequest) bool {
var step transferStep
if sif, ok := req.Session().Get("transferStep"); ok {
step = sif.(transferStep)
} else {
step = ReadAccount
}
switch step {
case ReadAccount:
if req.Input() == "" {
req.Prompt("Enter recipient account number")
} else {
req.Session().Set("transferAccount", req.Input())
req.Session().Set("transferStep", ReadAmount)
req.Prompt("Enter amount to transfer")
}
case ReadAmount:
if req.Input() == "" {
req.Prompt("Enter amount to transfer")
} else {
req.Session().Set("transferAmount", req.Input())
req.Session().Set("transferStep", ConfirmTransfer)
req.PromptWithTemplate(
"transfer/confirm.tmpl", grouter.TemplateValues{
"Account": req.Session().MustGet("transferAccount"),
"Amount": req.Session().MustGet("transferAmount"),
},
)
}
case ConfirmTransfer:
if req.Input() == "" {
req.PromptWithTemplate(
"transfer/confirm.tmpl", grouter.TemplateValues{
"Account": req.Session().MustGet("transferAccount"),
"Amount": req.Session().MustGet("transferAmount"),
},
)
} else {
switch req.Input() {
case "1":
req.End(
"🤙 You transferred %s to %s.",
req.Session().MustGet("transferAmount"),
req.Session().MustGet("transferAccount"),
)
case "#":
req.End("Transfer cancelled. Thank you. Come again")
case "3":
req.End("You entered a wrong option! Pay attention")
}
}
}
return true // retain the scrren context for the duration of the interaction
}
func showAccount(req grouter.UssdRequest) bool {
req.ContinueWithTemplate("account.tmpl", grouter.TemplateValues{"Phone": req.MSISDN()})
return false
}
func accountBalance(req grouter.UssdRequest) bool {
req.ContinueWithTemplate("balance.tmpl", grouter.TemplateValues{"Phone": req.MSISDN()})
return false
}
func miniStatement(req grouter.UssdRequest) bool {
req.ContinueWithTemplate("statement.tmpl", grouter.TemplateValues{"Phone": req.MSISDN()})
return false
}
func welcomeScreen(req grouter.UssdRequest) bool {
req.ContinueWithTemplate("main.tmpl", grouter.TemplateValues{"Phone": req.MSISDN()})
return false
}
func endSession(req grouter.UssdRequest) bool {
req.End("Thank you %s. Please come again!", req.MSISDN())
return false
}You can test the above code with the following USSD simulators