Middlewares

Middlewares are functions that are run before a command is invoked. They can be used to inject data into a command's plugin.Context, conditionalize execution, or do things like performance and stats tracking.

Adam itself provides middlewares on both a global and a per-plugin level. Aside from that, you can also add middlewares through the state. The order of execution is as follows.

1. A message create event or message update event is received by the state's event handler.

2. All global state middlewares are called.

3. The MessageCreateMiddlewares or MessageUpdateMiddlewares found in the bot's Options are called.

4. The router is called, which either routes the command or discards the message if it's not a command.

5. Adam's global middlewares are called.

6. The plugin's middlewares are called, starting from the highest-most module to the command itself.

7. Adam's global post-middlewares are called.

8. The command is invoked.

Adding middlewares

Global middlewares can be added using bot.Bot.AddMiddleware. Similarly, global post middlewares can be added using bot.Bot.AddPostMiddleware.

To get the plugin middlewares, the bot checks if interface { Middlewares() []bot.MiddlewareFunc } is implemented. Every module.Module already does that, and you can add middlewares using .AddMiddleware(f interface{}). However, commands, being custom types, need to implement that interface manually. You can do so by embedding a bot.MiddlewareManager into your command's struct, which adds the required Middlewares function, as well as an AddMiddleware function to add middlewares to the command.

Supported types

bot.MiddlewareManager, bot.Bot, and module.Module support the following middleware signatures:

• func(*state.State, interface{})

• func(*state.State, interface{}) error

• func(*state.State, *state.Base)

• func(*state.State, *state.Base) error

• func(*state.State, *state.MessageCreateEvent)

• func(*state.State, *state.MessageCreateEvent) error

• func(*state.State, *state.MessageUpdateEvent)

• func(*state.State, *state.MessageUpdateEvent) error

• func(next CommandFunc) CommandFunc