Table of Contents

Basic Operations Questions

In the following section, you will find commonly asked questions and answers regarding basic usage of the library, as well as language-specific tips when using this library.

How should I safely check a type?

Warning

Direct casting (e.g., (Type)type) is the least recommended way of casting, as it can throw an InvalidCastException when the object isn't the desired type.

Please refer to this post for more details.

In Discord.Net, the idea of polymorphism is used throughout. You may need to cast the object as a certain type before you can perform any action.

A good and safe casting example:

public async Task MessageReceivedHandler(SocketMessage msg)
{
   // Option 1:
   // Using the `as` keyword, which will return `null` if the object isn't the desired type.
   var usermsg = msg as SocketUserMessage;
   // We bail when the message isn't the desired type.
   if (msg == null) return;
   
   // Option 2:
   // Using the `is` keyword to cast (C#7 or above only)
   if (msg is SocketUserMessage usermsg) 
   {
      // Do things
   }
}

How do I send a message?

Tip

The GetChannel method by default returns an IChannel, allowing channel types such as IVoiceChannel, ICategoryChannel to be returned; consequently, you cannot send a message to channels like those.

Any implementation of IMessageChannel has a SendMessageAsync method. You can get the channel via GetChannel under the client. Remember, when using Discord.Net, polymorphism is a common recurring theme. This means an object may take in many shapes or form, which means casting is your friend. You should attempt to cast the channel as an IMessageChannel or any other entity that implements it to be able to message.

How can I tell if a message is from X, Y, Z channel?

You may check the message channel type. Visit Glossary to see the various types of channels.

How can I get the guild from a message?

There are 2 ways to do this. You can do either of the following,

  1. Cast the user as an IGuildUser and use its IGuild property.
  2. Cast the channel as an IGuildChannel and use its IGuild property.

How do I add hyperlink text to an embed?

Embeds can use standard markdown in the description field as well as in field values. With that in mind, links can be added with [text](link).

How do I add reactions to a message?

Any entity that implements IUserMessage has an AddReactionAsync method. This method expects an IEmote as a parameter. In Discord.Net, an Emote represents a custom-image emote, while an Emoji is a Unicode emoji (standard emoji). Both Emoji and Emote implement IEmote and are valid options.

// bail if the message is not a user one (system messages cannot have reactions)
var usermsg = msg as IUserMessage;
if (usermsg == null) return;

// standard Unicode emojis
Emoji emoji = new Emoji("👍");
// or
// Emoji emoji = new Emoji("\uD83D\uDC4D");

// custom guild emotes
Emote emote = Emote.Parse("<:dotnet:232902710280716288>");  
// using Emote.TryParse may be safer in regards to errors being thrown;
// please note that the method does not verify if the emote exists,
// it simply creates the Emote object for you.

// add the reaction to the message
await usermsg.AddReactionAsync(emoji); 
await usermsg.AddReactionAsync(emote);

What is a "preemptive rate limit?"

A preemptive rate limit is Discord.Net's way of telling you to slow down before you get hit by the real rate limit. Hitting a real rate limit might prevent your entire client from sending any requests for a period of time. This is calculated based on the HTTP header returned by a Discord response.

Why am I getting so many preemptive rate limits when I try to add more than one reactions?

This is due to how HTML header works, mistreating 0.25sec/action to 1sec. This causes the lib to throw preemptive rate limit more frequently than it should for methods such as adding reactions.

Can I opt-out of preemptive rate limits?

Unfortunately, not at the moment. See #401.

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