Enum diesel::result::Error

pub enum Error {
    InvalidCString(NulError),
    DatabaseError(DatabaseErrorKind, Box<dyn DatabaseErrorInformation + Send + Sync>),
    NotFound,
    QueryBuilderError(Box<dyn StdError + Send + Sync>),
    DeserializationError(Box<dyn StdError + Send + Sync>),
    SerializationError(Box<dyn StdError + Send + Sync>),
    RollbackTransaction,
    AlreadyInTransaction,
    // some variants omitted
}

Represents all the ways that a query can fail.

This type is not intended to be exhaustively matched, and new variants may be added in the future without a major version bump.

Variants

InvalidCString(NulError)

The query contained a nul byte.

This should never occur in normal usage.

DatabaseError(DatabaseErrorKind, Box<dyn DatabaseErrorInformation + Send + Sync>)

The database returned an error.

While Diesel prevents almost all sources of runtime errors at compile time, it does not attempt to prevent 100% of them. Typically this error will occur from insert or update statements due to a constraint violation.

NotFound

No rows were returned by a query expected to return at least one row.

This variant is only returned by get_result and first. load does not treat 0 rows as an error. If you would like to allow either 0 or 1 rows, call optional on the result.

QueryBuilderError(Box<dyn StdError + Send + Sync>)

The query could not be constructed

An example of when this error could occur is if you are attempting to construct an update statement with no changes (e.g. all fields on the struct are None).

DeserializationError(Box<dyn StdError + Send + Sync>)

An error occurred deserializing the data being sent to the database.

Typically this error means that the stated type of the query is incorrect. An example of when this error might occur in normal usage is attempting to deserialize an infinite date into chrono.

SerializationError(Box<dyn StdError + Send + Sync>)

An error occurred serializing the data being sent to the database.

An example of when this error would be returned is if you attempted to serialize a chrono::NaiveDate earlier than the earliest date supported by PostgreSQL.

RollbackTransaction

Roll back the current transaction.

You can return this variant inside of a transaction when you want to roll it back, but have no actual error to return. Diesel will never return this variant unless you gave it to us, and it can be safely ignored in error handling.

AlreadyInTransaction

Attempted to perform an operation that cannot be done inside a transaction when a transaction was already open.

Trait Implementations

impl PartialEq<Error> for Error

fn eq(&self, other: &Error) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use] fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl From<NulError> for Error

fn from(e: NulError) -> Self

Performs the conversion.

impl From<Error> for RunMigrationsError

fn from(e: Error) -> Self

Performs the conversion.

impl Display for Error

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl Debug for Error

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl Error for Error

fn description(&self) -> &str

This method is soft-deprecated.

fn cause(&self) -> Option<&dyn StdError>

Deprecating in 1.33.0

: replaced by Error::source, which can support downcasting

The lower-level cause of this error, if any.

fn source(&self) -> Option<&(dyn Error + 'static)>

The lower-level source of this error, if any.