Struct FromMapKeyError

pub struct FromMapKeyError { /* private fields */ }

Error type for failed map key conversions.

This error is returned when attempting to convert a CEL MapKey to a Rust type using the FromMapKey trait, but the conversion fails due to type mismatch.

Error Information

The error contains:

• Source key: The original CEL map key that could not be converted
• Target type: The intended map key type for the conversion

Map Key Constraints

Only certain types can be used as CEL map keys:

• bool - Boolean keys
• i64 - Signed integer keys
• u64 - Unsigned integer keys
• String - String keys

Common Causes

• Type mismatch: Trying to convert MapKey::String to i64
• Invalid key type: Attempting conversion to unsupported key type
• Format issues: Key value doesn’t meet target type constraints

Examples

use cel_cxx::{MapKey, FromMapKey, FromMapKeyError};

let string_key = MapKey::String("not_a_number".to_string().into());
let result = i64::from_mapkey(&string_key);

match result {
    Ok(num) => println!("Converted key: {}", num),
    Err(error) => {
        println!("Cannot convert key: {}", error);
    }
}

Implementations

impl FromMapKeyError

pub fn new(key: MapKey, to: MapKeyType) -> Self

Create a new map key conversion error.

Arguments

• key - The CEL map key that could not be converted
• to - The target map key type for the conversion

Examples

use cel_cxx::{MapKey, MapKeyType, FromMapKeyError};

let error = FromMapKeyError::new(
    MapKey::String("text".to_string().into()),
    MapKeyType::Int
);
// Error created successfully

pub fn new_typed<T: TypedMapKey>(key: MapKey) -> Self

Create a new map key conversion error with automatic type detection.

This method uses the TypedMapKey trait to automatically determine the CEL type information of the target type, providing more consistent error messages.

Type Parameters

• T - The target map key type that implements TypedMapKey

Arguments

• key - The CEL map key that could not be converted

Examples

use cel_cxx::{MapKey, FromMapKeyError};

let error = FromMapKeyError::new_typed::<i64>(MapKey::String("text".to_string().into()));
// error contains type information for the target type

Trait Implementations

impl Clone for FromMapKeyError

fn clone(&self) -> FromMapKeyError

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for FromMapKeyError

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

Formats the value using the given formatter.

impl Display for FromMapKeyError

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

Formats the value using the given formatter.

impl Error for FromMapKeyError

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.

impl From<FromMapKeyError> for Error

fn from(error: FromMapKeyError) -> Self

Converts to this type from the input type.

impl From<FromMapKeyError> for FromValueError

fn from(error: FromMapKeyError) -> Self

Converts to this type from the input type.