Crate edgedb_errors

Error Handling for EdgeDB

All errors that EdgeDB Rust bindings produce are encapsulated into the Error structure. The structure is a bit like Box<dyn Error> or anyhow::Error, except it can only contain EdgeDB error types. Or UserError can be used to encapsulate custom errors (commonly used to return error from the transaction).

Each error kind is represented as a separate type that implements ErrorKind trait. But error kinds are used like marker structs you can use Error::is for error kinds and use them to create instances of the error:

let err = UserError::with_source(io::Error::from(io::ErrorKind::NotFound));
assert!(err.is::<UserError>());

Since errors are hirarhical Error::is works with any ancestor:

assert!(err.is::<MissingArgumentError>());
assert!(err.is::<QueryArgumentError>());  // implied by the assertion above
assert!(err.is::<InterfaceError>());  // and this one
assert!(err.is::<ClientError>());  // and this one

Error hierarchy doesn’t have multiple inheritance (i.e. every error has only single parent). When we match across different parents we use error tags:

assert!(err1.is::<ClientConnectionTimeoutError>());
assert!(err2.is::<TransactionConflictError>());
// Both of these are retried
assert!(err1.has_tag(SHOULD_RETRY));
assert!(err2.has_tag(SHOULD_RETRY));

// But they aren't a part of common hierarchy
assert!(err1.is::<ClientError>());
assert!(!err1.is::<ExecutionError>());
assert!(err2.is::<ExecutionError>());
assert!(!err2.is::<ClientError>());

Errors in Transactions

Special care for errors must be taken in transactions. Generally:

1. Errors from queries should not be ignored, and should be propagagated up to the transaction function.
2. User errors can be encapsulated into UserError via one of the methods:
   • ErrorKind::with_source (for any std::error::Error)
   • ErrorKind::with_source_box already boxed error
   • ErrorKind::with_source_ref for smart wrappers such as anyhow::Error
3. Original query error must be propagated via error chain. It can be in the .source() chain but must not be swallowed, otherwise retrying transaction may work incorrectly.

Re-exports

pub use kinds::*;

Modules

display

kinds

Structs

Error

Error type returned from any EdgeDB call.

Tag

Tag that is used to group similar errors.

Traits

ErrorKind

Trait that marks EdgeDB errors.

ResultExt