feat(core): add DatabaseError

sqlx-core/src/error.rs

@@ -2,6 +2,10 @@ use std::borrow::Cow;
 use std::error::Error as StdError;
 use std::fmt::{self, Display, Formatter};
 
+mod database;
+
+pub use database::DatabaseError;
+
 pub type Result<T> = std::result::Result<T, Error>;
 
 #[derive(Debug)]
@@ -9,6 +13,8 @@ pub type Result<T> = std::result::Result<T, Error>;
 pub enum Error {
     Configuration { message: Cow<'static, str>, source: Option<Box<dyn StdError + Send + Sync>> },
 
+    Connect(Box<dyn DatabaseError>),
+
     Network(std::io::Error),
 }
 
@@ -30,14 +36,16 @@ impl Error {
 impl Display for Error {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
         match self {
-            Self::Network(source) => write!(f, "network: {}", source),
+            Self::Network(source) => write!(f, "{}", source),
+
+            Self::Connect(source) => write!(f, "{}", source),
 
             Self::Configuration { message, source: None } => {
-                write!(f, "configuration: {}", message)
+                write!(f, "{}", message)
             }
 
             Self::Configuration { message, source: Some(source) } => {
-                write!(f, "configuration: {}: {}", message, source)
+                write!(f, "{}: {}", message, source)
             }
         }
     }
@@ -57,12 +65,12 @@ impl StdError for Error {
 
 impl From<std::io::Error> for Error {
     fn from(error: std::io::Error) -> Self {
-        Error::Network(error)
+        Self::Network(error)
     }
 }
 
 impl From<std::io::ErrorKind> for Error {
     fn from(error: std::io::ErrorKind) -> Self {
-        Error::Network(error.into())
+        Self::Network(error.into())
     }
 }

sqlx-core/src/error/database.rs

@@ -0,0 +1,13 @@
+use std::error::Error as StdError;
+
+/// `DatabaseError` is a trait representing an error that was returned from
+/// the database.
+///
+/// Provides abstract access to information returned from the database about
+/// the error.
+///
+#[allow(clippy::module_name_repetitions)]
+pub trait DatabaseError: 'static + StdError + Send + Sync {
+    /// Returns the primary, human-readable error message.
+    fn message(&self) -> &str;
+}

sqlx-core/src/lib.rs

@@ -41,7 +41,7 @@ pub mod blocking;
 
 pub use connection::Connection;
 pub use database::{Database, HasOutput};
-pub use error::{Error, Result};
+pub use error::{Error, Result, DatabaseError};
 pub use options::ConnectOptions;
 #[cfg(feature = "actix")]
 pub use runtime::Actix;

sqlx-mysql/src/error.rs

@@ -0,0 +1,28 @@
+use std::error::Error as StdError;
+use std::fmt::{self, Display, Formatter};
+
+use sqlx_core::DatabaseError;
+
+use crate::protocol::ErrPacket;
+
+/// An error returned from the MySQL database server.
+#[allow(clippy::module_name_repetitions)]
+#[derive(Debug)]
+pub struct MySqlDatabaseError(pub(crate) ErrPacket);
+
+impl DatabaseError for MySqlDatabaseError {
+    fn message(&self) -> &str {
+        &self.0.error_message
+    }
+}
+
+impl Display for MySqlDatabaseError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        match &self.0.sql_state {
+            Some(state) => write!(f, "{} ({}): {}", self.0.error_code, state, self.message()),
+            None => write!(f, "{}: {}", self.0.error_code, self.message()),
+        }
+    }
+}
+
+impl StdError for MySqlDatabaseError {}