Cleaning the canister

Developers
1

Hi!
Is there a way to completely clear the canister of data?
Or let’s say there is a possibility of re-creation with an already known canister_id.?
It doesn’t really matter to me whether the logic remains there(.wasm) - that is, complete cleaning.

2

If you want to reinstall code to a canister and wipe all it’s state you can use the --mode reinstall flag

If you just want to wipe code and state use dfx canister uninstall-code

2 Likes
3

Thanks. OK, I have already used these operators in the project. Let’s say my code is below:

    public shared({caller}) func reinstall_wasm(
        canister_id : Principal, 
        wasm : Wasm) : async Bool {
            try{
                await actor_ic.install_code({arg = []; wasm_module = wasm; mode = #reinstall; canister_id = canister_id;});
                return true;
            }
            catch e { 
                Debug.print("reinstall_wasm: error: " # debug_show(Error.message(e)));
                return false; 
            }
    };

Completely clean the canister?

I understand correctly that the code:

    public func get_rts_memory_size(): async Nat {  
        return Prim.rts_memory_size();
    };

Will it return the number of bytes of an almost empty canister? Or will the byte size be equal to the already marked area before cleaning?

4

Depends on your definition of ‘completely clean’. This will clean the canister and then install the new wasm module. So it will be like a new canister that you installed code into for the first time. If you want a completely empty canister, you’ll have to use the uninstall_code function.

5

Thanks. I have not fully described the context of the question. I need to clarify. The fact is that I use the data saving functions when updating the code in the canister.

 system func preupgrade(){  // save logic };
 system func postupgrade(){ // save logic  };

That is, I need to definitely (without taking into account the operators above) delete all the data. It would be great if there was such a function. Thanks anyway. I will need to check everything in my tests.