steid

steid/src/domain/error.rs

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1	use std::fmt;
2
3	/// Every way a domain rule can be violated.
4	///
5	/// Deliberately coarse: a variant earns its place when a caller needs to react to it
6	/// differently, not merely to describe a failure more precisely.
7	#[derive(Debug, Clone, PartialEq, Eq)]
8	pub enum DomainError {
9	/// A value failed validation. Carries the field and the reason.
10	Validation { field: String, reason: String },
11	/// The requested entity does not exist.
12	NotFound { entity: &'static str },
13	/// The entity already exists and the operation requires it not to.
14	AlreadyExists { entity: &'static str },
15	/// Credentials did not match. Deliberately says nothing about which part failed.
16	InvalidCredentials,
17	}
18
19	impl DomainError {
20	pub fn validation(field: impl Into<String>, reason: impl Into<String>) -> Self {
21	Self::Validation {
22	field: field.into(),
23	reason: reason.into(),
24	}
25	}
26	}
27
28	impl fmt::Display for DomainError {
29	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
30	match self {
31	Self::Validation { field, reason } => write!(f, "invalid {field}: {reason}"),
32	Self::NotFound { entity } => write!(f, "{entity} not found"),
33	Self::AlreadyExists { entity } => write!(f, "{entity} already exists"),
34	Self::InvalidCredentials => f.write_str("invalid credentials"),
35	}
36	}
37	}
38
39	impl std::error::Error for DomainError {}