error refactor

rust/src/models/error.rs

@@ -0,0 +1,165 @@
+use std::convert;
+use std::fmt;
+
+use sqlx::error::DatabaseError as _;
+
+pub enum DatabaseError {
+    /// Errors we can receive **from** the database that are caused by connection
+    /// problems or schema problems (e.g. we get a return value that does not fit our enum,
+    /// or a wrongly formatted date)
+    Sql {
+        description: String,
+    },
+    Uuid {
+        description: String,
+    },
+    Enum {
+        description: String,
+    },
+    TimeParse {
+        description: String,
+    },
+}
+
+impl fmt::Display for DatabaseError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Self::Sql { description } => {
+                write!(f, "SQL error: {description}")
+            }
+            Self::Uuid { description } => {
+                write!(f, "UUID error: {description}")
+            }
+            Self::Enum { description } => {
+                write!(f, "Enum error: {description}")
+            }
+            Self::TimeParse { description } => {
+                write!(f, "Date parse error: {description}")
+            }
+        }
+    }
+}
+
+pub enum QueryError {
+    /// Errors that are caused by wrong input data, e.g. ids that cannot be found, or
+    /// inserts that violate unique constraints
+    Constraint {
+        description: String,
+    },
+    Duplicate {
+        description: String,
+    },
+    NotFound {
+        description: String,
+    },
+    ReferenceNotFound {
+        description: String,
+    },
+}
+
+impl fmt::Display for QueryError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Self::Constraint { description } => {
+                write!(f, "SQL constraint error: {description}")
+            }
+            Self::Duplicate { description } => {
+                write!(f, "Duplicate data entry: {description}")
+            }
+            Self::NotFound { description } => {
+                write!(f, "not found: {description}")
+            }
+            Self::ReferenceNotFound { description } => {
+                write!(f, "SQL foreign key reference was not found: {description}")
+            }
+        }
+    }
+}
+
+pub enum Error {
+    Database(DatabaseError),
+    Query(QueryError),
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Self::Database(error) => write!(f, "{}", error),
+            Self::Query(error) => write!(f, "{}", error),
+        }
+    }
+}
+
+impl fmt::Debug for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        // defer to Display
+        write!(f, "SQL error: {self}")
+    }
+}
+
+impl convert::From<uuid::Error> for Error {
+    fn from(value: uuid::Error) -> Self {
+        Error::Database(DatabaseError::Uuid {
+            description: value.to_string(),
+        })
+    }
+}
+
+impl convert::From<time::error::Format> for Error {
+    fn from(value: time::error::Format) -> Self {
+        Error::Database(DatabaseError::TimeParse {
+            description: value.to_string(),
+        })
+    }
+}
+
+impl convert::From<sqlx::Error> for Error {
+    fn from(value: sqlx::Error) -> Self {
+        match value {
+            sqlx::Error::RowNotFound => Error::Query(QueryError::NotFound {
+                description: value.to_string(),
+            }),
+            sqlx::Error::Database(ref error) => {
+                let sqlite_error = error.downcast_ref::<sqlx::sqlite::SqliteError>();
+                if let Some(code) = sqlite_error.code() {
+                    match &*code {
+                        // SQLITE_CONSTRAINT_FOREIGNKEY
+                        "787" => Error::Query(QueryError::Constraint {
+                            description: format!("foreign key reference not found"),
+                        }),
+                        // SQLITE_CONSTRAINT_UNIQUE
+                        "2067" => Error::Query(QueryError::Constraint {
+                            description: format!("item with unique constraint already exists",),
+                        }),
+                        _ => Error::Database(DatabaseError::Sql {
+                            description: format!(
+                                "got error with unknown code: {}",
+                                sqlite_error.to_string()
+                            ),
+                        }),
+                    }
+                } else {
+                    Error::Database(DatabaseError::Sql {
+                        description: format!(
+                            "got error without code: {}",
+                            sqlite_error.to_string()
+                        ),
+                    })
+                }
+            }
+            _ => Error::Database(DatabaseError::Sql {
+                description: format!("got unknown error: {}", value.to_string()),
+            }),
+        }
+    }
+}
+
+impl convert::From<time::error::Parse> for Error {
+    fn from(value: time::error::Parse) -> Self {
+        Error::Database(DatabaseError::TimeParse {
+            description: value.to_string(),
+        })
+    }
+}
+
+impl std::error::Error for Error {}