Take 2

src/Discord.Net.Rest/DiscordRestClient.cs

@@ -32,9 +32,15 @@ namespace Discord.Rest
         ///     Initializes a new <see cref="DiscordRestClient"/> with the provided configuration.
         /// </summary>
         /// <param name="config">The configuration to be used with the client.</param>
-        public DiscordRestClient(DiscordRestConfig config) : base(config, CreateApiClient(config)) { }
+        public DiscordRestClient(DiscordRestConfig config) : base(config, CreateApiClient(config))
+        {
+            APIOnInteractionCreation = config.APIOnRestInteractionCreation;
+        }
         // used for socket client rest access
-        internal DiscordRestClient(DiscordRestConfig config, API.DiscordRestApiClient api) : base(config, api) { }
+        internal DiscordRestClient(DiscordRestConfig config, API.DiscordRestApiClient api) : base(config, api)
+        {
+            APIOnInteractionCreation = config.APIOnRestInteractionCreation;
+        }
 
         private static API.DiscordRestApiClient CreateApiClient(DiscordRestConfig config)
             => new API.DiscordRestApiClient(config.RestClientProvider, DiscordRestConfig.UserAgent, serializer: Serializer, useSystemClock: config.UseSystemClock, defaultRatelimitCallback: config.DefaultRatelimitCallback);
@@ -82,6 +88,8 @@ namespace Discord.Rest
 
         #region Rest interactions
 
+        internal readonly bool APIOnInteractionCreation;
+
         public bool IsValidHttpInteraction(string publicKey, string signature, string timestamp, string body)
             => IsValidHttpInteraction(publicKey, signature, timestamp, Encoding.UTF8.GetBytes(body));
         public bool IsValidHttpInteraction(string publicKey, string signature, string timestamp, byte[] body)

src/Discord.Net.Rest/DiscordRestConfig.cs

@@ -9,5 +9,7 @@ namespace Discord.Rest
     {
         /// <summary> Gets or sets the provider used to generate new REST connections. </summary>
         public RestClientProvider RestClientProvider { get; set; } = DefaultRestClientProvider.Instance;
+
+        public bool APIOnRestInteractionCreation { get; set; } = true;
     }
 }

src/Discord.Net.Rest/Entities/Interactions/CommandBase/RestResolvableData.cs

@@ -38,15 +38,26 @@ namespace Discord.Rest
 
             if (resolved.Channels.IsSpecified)
             {
-                var channels = await guild.GetChannelsAsync().ConfigureAwait(false);
+                var channels = discord.APIOnInteractionCreation ? await guild.GetChannelsAsync().ConfigureAwait(false) : null;
 
                 foreach (var channelModel in resolved.Channels.Value)
                 {
-                    var restChannel = channels.FirstOrDefault(x => x.Id == channelModel.Value.Id);
+                    if (channels != null)
+                    {
+                        var guildChannel = channels.FirstOrDefault(x => x.Id == channelModel.Value.Id);
 
-                    restChannel.Update(channelModel.Value);
+                        guildChannel.Update(channelModel.Value);
 
-                    Channels.Add(ulong.Parse(channelModel.Key), restChannel);
+                        Channels.Add(ulong.Parse(channelModel.Key), guildChannel);
+                    }
+                    else
+                    {
+                        var restChannel = RestChannel.Create(discord, channelModel.Value);
+
+                        restChannel.Update(channelModel.Value);
+
+                        Channels.Add(ulong.Parse(channelModel.Key), restChannel);
+                    }
                 }
             }
 
@@ -76,7 +87,10 @@ namespace Discord.Rest
             {
                 foreach (var msg in resolved.Messages.Value)
                 {
-                    channel ??= (IRestMessageChannel)(Channels.FirstOrDefault(x => x.Key == msg.Value.ChannelId).Value ?? await discord.GetChannelAsync(msg.Value.ChannelId).ConfigureAwait(false));
+                    channel ??= (IRestMessageChannel)(Channels.FirstOrDefault(x => x.Key == msg.Value.ChannelId).Value
+                        ?? (discord.APIOnInteractionCreation
+                        ? await discord.GetChannelAsync(msg.Value.ChannelId).ConfigureAwait(false)
+                        : null));
 
                     RestUser author;
 

src/Discord.Net.Rest/Entities/Interactions/RestInteraction.cs

@@ -31,6 +31,10 @@ namespace Discord.Rest
         /// <summary>
         ///     Gets the user who invoked the interaction.
         /// </summary>
+        /// <remarks>
+        ///     If this user is an <see cref="RestGuildUser"/> and <see cref="DiscordRestConfig.APIOnRestInteractionCreation"/> is set to false,
+        ///     <see cref="RestGuildUser.Guild"/> will return <see langword="null"/>
+        /// </remarks>
         public RestUser User { get; private set; }
 
         /// <inheritdoc/>
@@ -51,11 +55,17 @@ namespace Discord.Rest
         /// <summary>
         ///     Gets the channel that this interaction was executed in.
         /// </summary>
+        /// <remarks>
+        ///     <see langword="null"/> if <see cref="DiscordRestConfig.APIOnRestInteractionCreation"/> is set to false.
+        /// </remarks>
         public IRestMessageChannel Channel { get; private set; }
 
         /// <summary>
-        ///     Gets the guild this interaction was executed in.
+        ///     Gets the guild this interaction was executed in if applicable.
         /// </summary>
+        /// <remarks>
+        ///     <see langword="null"/> if <see cref="DiscordRestConfig.APIOnRestInteractionCreation"/> is set to false.
+        /// </remarks>
         public RestGuild Guild { get; private set; }
 
         /// <inheritdoc/>
@@ -122,7 +132,10 @@ namespace Discord.Rest
 
             if(Guild == null && model.GuildId.IsSpecified)
             {
-                Guild = await discord.GetGuildAsync(model.GuildId.Value);
+                if (discord.APIOnInteractionCreation)
+                    Guild = await discord.GetGuildAsync(model.GuildId.Value);
+                else
+                    Guild = null;
             }
 
             if (User == null)
@@ -141,7 +154,10 @@ namespace Discord.Rest
             {
                 try
                 {
-                    Channel = (IRestMessageChannel)await discord.GetChannelAsync(model.ChannelId.Value);
+                    if (discord.APIOnInteractionCreation)
+                        Channel = (IRestMessageChannel)await discord.GetChannelAsync(model.ChannelId.Value);
+                    else
+                        Channel = null;
                 }
                 catch(HttpException x) when(x.DiscordCode == DiscordErrorCode.MissingPermissions) { } // ignore
             }