Struct DependencyScopeError 

pub struct DependencyScopeError {
    pub request_scoped_type: String,
    pub function_scoped_type: String,
}

Error returned when a dependency scope constraint is violated.

This occurs when a request-scoped dependency depends on a function-scoped dependency. Since request-scoped dependencies are cached for the lifetime of the request, they would hold stale values from function-scoped dependencies (which should be resolved fresh on each call).

Example

Dependency scope violation: request-scoped 'CachedUser' depends on
function-scoped 'DbConnection'. Request-scoped dependencies cannot
depend on function-scoped dependencies because the cached value
would become stale.

Why This Matters

Consider this scenario:

• CachedUser is request-scoped (cached for the request)
• DbConnection is function-scoped (fresh connection each call)

If CachedUser depends on DbConnection:

1. First request: CachedUser resolved, caches DbConnection value
2. Later in same request: CachedUser retrieved from cache
3. Problem: The cached CachedUser holds a stale DbConnection

This violates the contract that function-scoped dependencies are fresh.

Fields

request_scoped_type: String

The name of the request-scoped dependency (the outer one).

function_scoped_type: String

The name of the function-scoped dependency (the inner one).

Implementations

impl DependencyScopeError

pub fn new(request_scoped_type: String, function_scoped_type: String) -> Self

Create a new scope violation error.

Trait Implementations

impl Clone for DependencyScopeError

fn clone(&self) -> DependencyScopeError

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for DependencyScopeError

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

Formats the value using the given formatter.

impl Display for DependencyScopeError

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

Formats the value using the given formatter.

impl Error for DependencyScopeError

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 IntoResponse for DependencyScopeError

fn into_response(self) -> Response

Convert into a response.