Overview
CommandHandler is an abstract base class for handlers that process command messages. This handler is triggered when users send bot commands (messages starting with ’/’) and provides functionality to extract and parse command arguments.
Attribute
[CommandHandler(importance: 1)]
The importance level of the handler. Default is 1 (higher than MessageHandler).
Base Class
public abstract class CommandHandler : MessageHandler
MessageHandler, which provides all message handling capabilities.
Properties
ReceivedCommand
protected string ReceivedCommand { get; }
/start@mybot, ReceivedCommand will be "start".
Arguments
protected string[] Arguments { get; }
/search foo bar, Arguments will be ["foo", "bar"].
ArgumentsString
protected string ArgumentsString { get; }
/search hello world, ArgumentsString will be "hello world".
Methods
Execute
public abstract Task<Result> Execute(
IHandlerContainer<Message> container,
CancellationToken cancellation
)
MessageHandler.
container
IHandlerContainer<Message>
required
The handler container with message update data.
cancellation
CancellationToken
required
Cancellation token for the operation.
Task<Result> - A result indicating success, fault, or continuation.
All methods from MessageHandler are available:
Reply() - Send a reply to the command messageResponse() - Send a response to the chat
How Commands are Recognized
The CommandHandlerAttribute checks if:
- The message contains entities
- The first entity is of type
BotCommand
- The command starts at position 0 in the message
- The command is extracted (removing ’/’ and optional ‘@botname’)
Examples
Basic Command Handler
using Telegrator.Handlers;
using Telegrator.Filters;
using Telegram.Bot.Types.Enums;
[CommandHandler]
[CommandFilter("start")]
public class StartCommandHandler : CommandHandler
{
public override async Task<Result> Execute(
IHandlerContainer<Message> container,
CancellationToken cancellation)
{
await Reply(
$"Welcome! You executed the '{ReceivedCommand}' command.",
parseMode: ParseMode.Html
);
return Result.Ok();
}
}
Command with Arguments
[CommandHandler]
[CommandFilter("search")]
public class SearchCommandHandler : CommandHandler
{
public override async Task<Result> Execute(
IHandlerContainer<Message> container,
CancellationToken cancellation)
{
if (Arguments.Length == 0)
{
await Reply("Please provide a search query.");
return Result.Ok();
}
string query = ArgumentsString;
await Reply($"Searching for: {query}");
// Perform search logic here...
return Result.Ok();
}
}
Multiple Commands in One Handler
[CommandHandler]
public class MultiCommandHandler : BranchingCommandHandler
{
[CommandFilter("help")]
public async Task<Result> HandleHelp()
{
await Reply("Available commands: /help, /about, /settings");
return Result.Ok();
}
[CommandFilter("about")]
public async Task<Result> HandleAbout()
{
await Reply("This is my awesome bot!");
return Result.Ok();
}
[CommandFilter("settings")]
public async Task<Result> HandleSettings()
{
if (Arguments.Length > 0)
{
await Reply($"Updating setting: {Arguments[0]}");
}
else
{
await Reply("Current settings...");
}
return Result.Ok();
}
}
Parsing Structured Arguments
[CommandHandler]
[CommandFilter("set")]
public class SetCommandHandler : CommandHandler
{
public override async Task<Result> Execute(
IHandlerContainer<Message> container,
CancellationToken cancellation)
{
// Example: /set key value
if (Arguments.Length < 2)
{
await Reply(
"Usage: /set <key> <value>",
parseMode: ParseMode.Html
);
return Result.Ok();
}
string key = Arguments[0];
string value = string.Join(" ", Arguments.Skip(1));
await Reply($"Set {key} = {value}");
return Result.Ok();
}
}
BranchingCommandHandler
BranchingCommandHandler extends BranchingMessageHandler with command parsing capabilities.
public abstract class BranchingCommandHandler : BranchingMessageHandler
ReceivedCommand, Arguments, ArgumentsString) are available in branching handlers.
See Also