103 lines
3.4 KiB
Markdown
103 lines
3.4 KiB
Markdown
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---
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uid: Discord.Commands.PreconditionAttribute
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remarks: *content
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---
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This precondition attribute can be applied on module-level or
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method-level for a command.
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[!include[Additional Remarks](PreconditionAttribute.Remarks.Inclusion.md)]
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---
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uid: Discord.Commands.ParameterPreconditionAttribute
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remarks: *content
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---
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This precondition attribute can be applied on parameter-level for a
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command.
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[!include[Additional Remarks](PreconditionAttribute.Remarks.Inclusion.md)]
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---
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uid: Discord.Commands.PreconditionAttribute
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example: [*content]
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---
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The following example creates a precondition to see if the user has
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sufficient role required to access the command.
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```cs
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public class RequireRoleAttribute : PreconditionAttribute
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{
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private readonly ulong _roleId;
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public RequireRoleAttribute(ulong roleId)
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{
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_roleId = roleId;
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}
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public override async Task<PreconditionResult> CheckPermissionsAsync(ICommandContext context,
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CommandInfo command, IServiceProvider services)
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{
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var guildUser = context.User as IGuildUser;
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if (guildUser == null)
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return PreconditionResult.FromError("This command cannot be executed outside of a guild.");
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var guild = guildUser.Guild;
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if (guild.Roles.All(r => r.Id != _roleId))
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return PreconditionResult.FromError(
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$"The guild does not have the role ({_roleId}) required to access this command.");
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return guildUser.RoleIds.Any(rId => rId == _roleId)
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? PreconditionResult.FromSuccess()
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: PreconditionResult.FromError("You do not have the sufficient role required to access this command.");
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}
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}
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```
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---
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uid: Discord.Commands.ParameterPreconditionAttribute
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example: [*content]
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---
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The following example creates a precondition on a parameter-level to
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see if the targeted user has a lower hierarchy than the user who
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executed the command.
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```cs
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public class RequireHierarchyAttribute : ParameterPreconditionAttribute
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{
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public override async Task<PreconditionResult> CheckPermissionsAsync(ICommandContext context,
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ParameterInfo parameter, object value, IServiceProvider services)
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{
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// Hierarchy is only available under the socket variant of the user.
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if (!(context.User is SocketGuildUser guildUser))
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return PreconditionResult.FromError("This command cannot be used outside of a guild.");
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SocketGuildUser targetUser;
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switch (value)
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{
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case SocketGuildUser targetGuildUser:
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targetUser = targetGuildUser;
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break;
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case ulong userId:
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targetUser = await context.Guild.GetUserAsync(userId).ConfigureAwait(false) as SocketGuildUser;
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break;
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default:
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throw new ArgumentOutOfRangeException();
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}
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if (targetUser == null)
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return PreconditionResult.FromError("Target user not found.");
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if (guildUser.Hierarchy < targetUser.Hierarchy)
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return PreconditionResult.FromError("You cannot target anyone else whose roles are higher than yours.");
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var currentUser = await context.Guild.GetCurrentUserAsync().ConfigureAwait(false) as SocketGuildUser;
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if (currentUser?.Hierarchy < targetUser.Hierarchy)
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return PreconditionResult.FromError("The bot's role is lower than the targeted user.");
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return PreconditionResult.FromSuccess();
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}
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}
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```
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