124 lines
4.3 KiB
Markdown
124 lines
4.3 KiB
Markdown
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---
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uid: FAQ.Basics.BasicOp
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title: Basic Operations Questions
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---
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# Basic Operations Questions
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In the following section, you will find commonly asked questions and
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answers regarding basic usage of the library, as well as
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language-specific tips when using this library.
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## How should I safely check a type?
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> [!WARNING]
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> Direct casting (e.g., `(Type)type`) is **the least recommended**
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> way of casting, as it _can_ throw an [InvalidCastException]
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> when the object isn't the desired type.
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>
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> Please refer to [this post] for more details.
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In Discord.Net, the idea of polymorphism is used throughout. You may
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need to cast the object as a certain type before you can perform any
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action.
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A good and safe casting example:
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[!code-csharp[Casting](samples/cast.cs)]
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[invalidcastexception]: https://docs.microsoft.com/en-us/dotnet/api/system.invalidcastexception
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[this post]: https://docs.microsoft.com/en-us/dotnet/csharp/how-to/safely-cast-using-pattern-matching-is-and-as-operators
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## How do I send a message?
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> [!TIP]
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> The [GetChannel] method by default returns an [IChannel], allowing
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> channel types such as [IVoiceChannel], [ICategoryChannel]
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> to be returned; consequently, you cannot send a message
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> to channels like those.
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Any implementation of [IMessageChannel] has a [SendMessageAsync]
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method. You can get the channel via [GetChannel] under the client.
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Remember, when using Discord.Net, polymorphism is a common recurring
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theme. This means an object may take in many shapes or form, which
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means casting is your friend. You should attempt to cast the channel
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as an [IMessageChannel] or any other entity that implements it to be
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able to message.
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[sendmessageasync]: xref:Discord.IMessageChannel.SendMessageAsync*
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[getchannel]: xref:Discord.WebSocket.DiscordSocketClient.GetChannel*
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## How can I tell if a message is from X, Y, Z channel?
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You may check the message channel type. Visit [Glossary] to see the
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various types of channels.
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[Glossary]: xref:Guides.Entities.Glossary#channels
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## How can I get the guild from a message?
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There are 2 ways to do this. You can do either of the following,
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1. Cast the user as an [IGuildUser] and use its [IGuild] property.
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2. Cast the channel as an [IGuildChannel] and use its [IGuild] property.
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## How do I add hyperlink text to an embed?
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Embeds can use standard [markdown] in the description field as well
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as in field values. With that in mind, links can be added with
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`[text](link)`.
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[markdown]: https://support.discordapp.com/hc/en-us/articles/210298617-Markdown-Text-101-Chat-Formatting-Bold-Italic-Underline-
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## How do I add reactions to a message?
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Any entity that implements [IUserMessage] has an [AddReactionAsync]
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method. This method expects an [IEmote] as a parameter.
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In Discord.Net, an Emote represents a custom-image emote, while an
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Emoji is a Unicode emoji (standard emoji). Both [Emoji] and [Emote]
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implement [IEmote] and are valid options.
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# [Adding a reaction to another message](#tab/emoji-others)
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[!code-csharp[Emoji](samples/emoji-others.cs)]
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# [Adding a reaction to a sent message](#tab/emoji-self)
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[!code-csharp[Emoji](samples/emoji-self.cs)]
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---
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[addreactionasync]: xref:Discord.IMessage.AddReactionAsync*
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## What is a "preemptive rate limit?"
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A preemptive rate limit is Discord.Net's way of telling you to slow
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down before you get hit by the real rate limit. Hitting a real rate
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limit might prevent your entire client from sending any requests for
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a period of time. This is calculated based on the HTTP header
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returned by a Discord response.
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## Why am I getting so many preemptive rate limits when I try to add more than one reactions?
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This is due to how HTML header works, mistreating
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0.25sec/action to 1sec. This causes the lib to throw preemptive rate
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limit more frequently than it should for methods such as adding
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reactions.
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## Can I opt-out of preemptive rate limits?
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Unfortunately, not at the moment. See [#401](https://github.com/discord-net/Discord.Net/issues/401).
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[IChannel]: xref:Discord.IChannel
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[ICategoryChannel]: xref:Discord.ICategoryChannel
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[IGuildChannel]: xref:Discord.IGuildChannel
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[ITextChannel]: xref:Discord.ITextChannel
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[IGuild]: xref:Discord.IGuild
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[IVoiceChannel]: xref:Discord.IVoiceChannel
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[IGuildUser]: xref:Discord.IGuildUser
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[IMessageChannel]: xref:Discord.IMessageChannel
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[IUserMessage]: xref:Discord.IUserMessage
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[IEmote]: xref:Discord.IEmote
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[Emote]: xref:Discord.Emote
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[Emoji]: xref:Discord.Emoji
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