++

src/example/paid_service/src/lib.rs

@@ -7,7 +7,7 @@ use ic_papi_api::{Account, PaymentError};
 use ic_papi_guard::guards::attached_cycles::AttachedCyclesPayment;
 use ic_papi_guard::guards::icrc2_from_caller::Icrc2FromCaller;
 use ic_papi_guard::guards::PaymentGuard;
-use state::{payment_ledger, set_init_args};
+use state::{own_canister_id, payment_ledger, set_init_args};
 
 #[init]
 fn init(init_args: Option<InitArgs>) {
@@ -32,6 +32,7 @@ async fn cost_1000_attached_cycles() -> Result<String, PaymentError> {
 #[update()]
 async fn cost_1000_icrc2_from_caller() -> Result<String, PaymentError> {
     let guard = Icrc2FromCaller {
+        own_canister_id: own_canister_id(),
         payer: Account {
             owner: ic_cdk::caller(),
             subaccount: None,

src/example/paid_service/src/state.rs

@@ -14,13 +14,18 @@ where
     INIT_ARGS.with(|init_args| f(init_args.borrow().as_ref().expect("No init args provided")))
 }
 
+/// Provides own canister ID
+pub fn own_canister_id() -> Principal {
+    init_element(|init_args| init_args.own_canister_id.clone())
+}
+
 /// Provides the canister_id of the ledger used for payments.
 pub fn payment_ledger() -> Principal {
     init_element(|init_args| {
         init_args
             .ledger
-            .clone()
             .expect("Init args specify no ledger")
+            .clone()
     })
 }
 

src/example/paid_service/tests/it/icrc2.rs

@@ -43,10 +43,13 @@ impl Default for CallerPaysWithIcRc2TestSetup {
         let paid_service = PicCanisterBuilder::default()
             .with_wasm(&PicCanister::cargo_wasm_path("example_paid_service"))
             .with_canister(paid_service.clone())
-            .with_arg(encode_one(Some(InitArgs{
-                ledger: Some(ledger.canister_id()),
-                own_canister_id: paid_service,
-            })).unwrap())
+            .with_arg(
+                encode_one(Some(InitArgs {
+                    ledger: Some(ledger.canister_id()),
+                    own_canister_id: paid_service,
+                }))
+                .unwrap(),
+            )
             .deploy_to(pic.clone());
         let user =
             Principal::from_text("xzg7k-thc6c-idntg-knmtz-2fbhh-utt3e-snqw6-5xph3-54pbp-7axl5-tae")

src/guard/src/guards/icrc2_from_caller.rs

@@ -8,13 +8,15 @@ pub struct Icrc2FromCaller {
     pub payer: cycles_ledger_client::Account,
     /// The ledger to deduct the charge from.
     pub ledger_canister_id: Principal,
+    /// Own canister ID
+    pub own_canister_id: Principal,
 }
 
 impl PaymentGuard for Icrc2FromCaller {
     async fn deduct(&self, fee: u64) -> Result<(), PaymentError> {
         cycles_ledger_client::Service(self.ledger_canister_id)
             .withdraw_from(&WithdrawFromArgs {
-                to: Principal::anonymous(), // TODO: Should presumably be the canister ID of the service
+                to: self.own_canister_id.clone(),
                 from: self.payer.clone(),
                 amount: Nat::from(fee),
                 spender_subaccount: None,