InterceptedCommand

Implements: ICommand

Description

The InterceptedCommand allows you to implement a command wrapped by an interceptor. Thus, it allows you to build command call chains, where the interceptor can alter execution and delegate calls to a next command, which can then be intercepted or not.

Constructors

Creates a new InterceptedCommand, which serves as a link in an execution chain. Contains information about the interceptor that is being used and the next command in the chain.

public constructor(interceptor: ICommandInterceptor, next: ICommand)

• interceptor: ICommandInterceptor - interceptor that is intercepting the command.
• next: ICommand - (link to) the next command in the command’s execution chain.

Instance methods

execute

Executes the next command in the execution chain using the given parameters (arguments).
See Parameters

public execute(context: IContext, args: Parameters): Promise<any>

• context: IContext - a context to trace execution through a call chain.
• args: Parameters - parameters (arguments) to pass to the command for execution.
• returns: Promise<any> - execution result

getName

Returns a string with the name of the command that is being intercepted.

public getName(c): string

• returns: string - name of the command that is being intercepted.

validate

Validates the parameters (arguments) that are to be passed to the command that is next in the execution chain.
See Parameters, ValidationResult

public validate(args: Parameters): ValidationResult[]

• args: Parameters - parameters (arguments) to validate for the next command.
• returns: ValidationResult[] - array of ValidationResults.

Examples

export class CommandLogger implements ICommandInterceptor {       
        
    public getName(command: ICommand): string {
        return command.getName();
    }
          
    public async execute(context: IContext, command: ICommand, args: Parameters): Promise\<any\> {
        console.log("Executed command " + command.getName());
        await command.execute(context, args);
    }
          
    private validate(command: ICommand, args: Parameters): ValidationResult[] {
        return command.validate(args);
    }
}
   
let logger = new CommandLogger();
let loggedCommand = new InterceptedCommand(logger, command); 

// Each called command will output: Executed command <command name>

See also

• ICommand

• ICommandInterceptor