Enum ValidationError

pub enum ValidationError {
    Empty,
    TooLong {
        max: usize,
        actual: usize,
    },
    TooShort {
        min: usize,
        actual: usize,
    },
    InvalidFormat(String),
    OutOfRange(String),
    Custom(String),
}

Errors that can occur during validation of smart constructor inputs.

ValidationError represents failures when constructing domain types from raw input. These should be rare in practice because validation happens at system boundaries when parsing user input into domain types.

Design Philosophy

In a type-driven system, validation errors only occur at the edges where unstructured data enters the system. Once data is parsed into domain types, those types guarantee validity throughout the program.

Example Usage

use eventcore::types::StreamId;
use eventcore::errors::ValidationError;

match StreamId::try_new(user_input) {
    Ok(stream_id) => {
        // stream_id is guaranteed valid from here on
        process_stream(stream_id).await?;
    }
    Err(validation_error) => {
        // Show error to user and ask for corrected input
        match validation_error {
            ValidationError::Empty => {
                println!("Stream ID cannot be empty");
            }
            ValidationError::TooLong { max, actual } => {
                println!("Stream ID too long: {actual} chars (max: {max})");
            }
            _ => println!("Invalid stream ID: {}", validation_error),
        }
    }
}

Variants

Empty

The input was empty when a non-empty value was required.

TooLong

The input exceeded the maximum allowed length.

Fields

max: usize

Maximum allowed length

actual: usize

Actual length provided

TooShort

The input did not meet the minimum required length.

Fields

min: usize

Minimum required length

actual: usize

Actual length provided

InvalidFormat(String)

The input contained invalid characters or format.

OutOfRange(String)

The input value was out of the allowed range.

Custom(String)

A custom validation rule failed.

Trait Implementations

impl Clone for ValidationError

fn clone(&self) -> ValidationError

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ValidationError

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

Formats the value using the given formatter.

impl Diagnostic for ValidationError

fn code<'a>(&'a self) -> Option<Box<dyn Display + 'a>>

Unique diagnostic code that can be used to look up more information about this Diagnostic. Ideally also globally unique, and documented in the toplevel crate’s documentation for easy searching. Rust path format (foo::bar::baz) is recommended, but more classic codes like E0123 or enums will work just fine.

fn severity(&self) -> Option<Severity>

Diagnostic severity. This may be used by ReportHandlers to change the display format of this diagnostic.

fn help<'a>(&'a self) -> Option<Box<dyn Display + 'a>>

Additional help text related to this Diagnostic. Do you have any advice for the poor soul who’s just run into this issue?

fn url<'a>(&'a self) -> Option<Box<dyn Display + 'a>>

URL to visit for a more detailed explanation/help about this Diagnostic.

fn source_code(&self) -> Option<&dyn SourceCode>

Source code to apply this Diagnostic’s Diagnostic::labels to.

fn labels(&self) -> Option<Box<dyn Iterator<Item = LabeledSpan> + '_>>

Labels to apply to this Diagnostic’s Diagnostic::source_code

fn related<'a>( &'a self, ) -> Option<Box<dyn Iterator<Item = &'a dyn Diagnostic> + 'a>>

Additional related Diagnostics.

fn diagnostic_source(&self) -> Option<&dyn Diagnostic>

The cause of the error.

impl Display for ValidationError

fn fmt(&self, __formatter: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Error for ValidationError

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

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0: use the Display impl or to_string()

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

👎Deprecated since 1.33.0: replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.