There are two canisters, and when using a function in canister A to call a function in canister B, need to pass in the canister id <Principal> of canister A as a parameter, so is there any way to get the canister id in the motoko code? like address(this) in Ethereum solidity One way that is not so …

While that solution works, it’s quite slow since it requires an expensive await. A more direct solution is to declare the optional this parameter of the actor or actor class and return its principal using the Principal.fromActor base library function. Something like: import Principal "mo:base/Prin…

dfinity/examples/blob/master/motoko/whoami/src/Main.mo#L22 return someone; }; // Return the principal identifier of the caller of this method. public shared (message) func whoami() : async Principal { return message.caller; }; // Return the principal identifier of this c…

Interesting The call Principal.fromActor(this) is basically free compared to 18k~ cycles burned by the await call cf. Main.mo // Return the principal identifier of this canister. public func id() : async (Principal, Nat, Nat) { let before = Cycles.balance(); let result = await whoam…

Yes, it’s essentially free. The only cost here is the enclosing method itself, but if you were using it to pass on the principal of actor A to actor B as an explicit argument, just obtaining the principal of A can be dead cheap.

[image] claudio: shared (install) actor class WhoAmI(someone : Principal) = this { // Bind the optional `this` argument (any name will do) ... Actor class is ok: actor class Test() = this { and actor is not ok: actor Test = this { Stdout: Stderr: main.mo:6.14-6.18: syntax error [M00…

For an actor declaration, you can just pass the name of the actor (the name, if provided, is the “this” reference). actor Test { ... public func idQuick() : async Principal { return Principal.fromActor(Test); }; } (Classes need additional syntax to reference “this” because th…

[image] claudio: (Classes need additional syntax to reference “this” because the name of the class names the constructor (a function), not the instance being constructed (an object)). Hi, do you know how to refer to the identity of a class?

I’m note sure I understand the question, but does the example above not answer it? [image] claudio: import Principal "mo:base/Principal"; shared (install) actor class WhoAmI(someone : Principal) = this { // Bind the optional `this` argument (any name will do) ... // Return the principa…

Binding this to the actor class to obtain its principal id, however, calling it from next js file an error Error: Impossible to convert undefined to Principal. is thrown while trying to pass some inputs from a form.

I’m trying to use this approach : [image] claudio: actor Test { ... public func idQuick() : async Principal { return Principal.fromActor(Test); }; } But I get an error, is this approach no longer allowed? This is the error : cannot use Test before Test has been defined…

I have this in my code somewhere: actor class Test() = self { func a() : async Principal { return Principal.fromActor(self); } }

How to get the canister identifier in the motoko code?

Developers

ggreif October 10, 2024, 3:59pm 16

Indeed. See What is special about actor wrapper and this? - Motoko - #4 by ggreif.

Topic		Replies	Views
Getting actor (class) from Principal Language Support Motoko	2	962	February 23, 2022
How to call a canister by using canister principal in a canister? Language Support Motoko	3	915	January 30, 2022
Calling CANISTER_ID env variable in motoko Developers	1	375	July 14, 2022
Motoko actor class canister id Motoko	7	693	October 22, 2024
Check if function is called from another canister Developers	21	2445	July 11, 2024

How to get the canister identifier in the motoko code?

Related topics