Enum cqrs_core::Precondition

pub enum Precondition {
    New,
    Exists,
    ExpectedVersion(Version),
}

A precondition that must be upheld for a command to be executed or for events to be persisted.

Variants

New

Requires that the target aggregate must not have had any events previously applied to it.

Exists

Requires that the target event at least exist, whether as a snapshot, or as having had at least one event applied.

ExpectedVersion(Version)

Requires that the target aggregate have the exact version specified.

Methods

impl Precondition

pub fn verify(self, current_version: Option<Version>) -> Result<(), Self>

Verifies that the precondition holds, given the current_version. If the precondition is violated, an error is returned with the precondition.

Trait Implementations

impl From<Version> for Precondition

fn from(v: Version) -> Self

Performs the conversion.

impl Clone for Precondition

fn clone(&self) -> Precondition

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Precondition

impl Eq for Precondition

impl PartialEq<Precondition> for Precondition

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

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

fn ne(&self, other: &Precondition) -> bool

This method tests for !=.

impl Debug for Precondition

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

Formats the value using the given formatter.

impl Display for Precondition

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

Formats the value using the given formatter.

impl Hash for Precondition

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given [Hasher].

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given [Hasher].