isController

Check if a given principal is a controller of the canister.

import { isController, msgCaller, IDL, query, update } from 'azle';

export default class {
    @query([IDL.Principal], IDL.Bool)
    checkController(principal: Principal): boolean {
        return isController(principal);
    }

    @update([IDL.Text], IDL.Text)
    adminOnlyFunction(data: string): string {
        const caller = msgCaller();

        if (!isController(caller)) {
            throw new Error('Access denied: caller is not a controller');
        }

        return `Admin processed: ${data}`;
    }

    @query([], IDL.Bool)
    amIController(): boolean {
        return isController(msgCaller());
    }
}

The isController function checks whether a given principal is a controller of the current canister. Controllers have administrative privileges and can upgrade the canister.

Parameters:

• principal: The principal to check (Principal)

Returns: true if the principal is a controller, false otherwise

Use Cases:

• Implement controller-only functions
• Access control for administrative operations
• Security checks before sensitive operations
• Role-based permissions

Important Notes:

• Controllers are set during canister creation or by other controllers
• Controllers can upgrade the canister code
• Use for high-privilege operations only