Struct ResponseValidationError 

pub struct ResponseValidationError {
    pub errors: Vec<ValidationError>,
    pub response_content: Option<Value>,
    pub summary: Option<String>,
    pub debug_info: Option<DebugInfo>,
}

Response validation error for internal failures (500 Internal Server Error).

This error type is used when a response fails to serialize or validate against the expected response model. Unlike ValidationErrors which indicates client errors (422), this represents a bug in the server code and returns a 500 status.

When This Is Used

• Response fails to serialize to JSON
• Response doesn’t match the declared response_model
• Internal data transformation fails

Security Note

Error details and the original response content are logged server-side but are NOT exposed to clients (unless debug mode is explicitly enabled). This prevents leaking internal implementation details.

Examples

use fastapi_core::error::{ResponseValidationError, ValidationError, loc};

// Serialization failure
let error = ResponseValidationError::serialization_failed(
    "failed to serialize field 'created_at': invalid date format"
);

// Response model validation failure
let error = ResponseValidationError::new()
    .with_error(ValidationError::missing(loc::response_field("user_id")))
    .with_response_content(serde_json::json!({"name": "Alice"}));

Fields

errors: Vec<ValidationError>

The validation errors that occurred.

response_content: Option<Value>

The response content that failed validation (for logging only). This is NOT included in the response to clients.

summary: Option<String>

A summary message for logging.

debug_info: Option<DebugInfo>

Debug information (only included in response when debug mode is enabled).

Implementations

impl ResponseValidationError

pub fn new() -> Self

Create a new empty response validation error.

pub fn serialization_failed(message: impl Into<String>) -> Self

Create a serialization failure error.

Use this when response serialization to JSON fails.

pub fn model_validation_failed(message: impl Into<String>) -> Self

Create a response model validation failure error.

Use this when the response doesn’t match the declared response_model.

pub fn with_error(self, error: ValidationError) -> Self

Add a validation error.

pub fn with_errors( self, errors: impl IntoIterator<Item = ValidationError>, ) -> Self

Add multiple validation errors.

pub fn with_response_content(self, content: Value) -> Self

Set the response content that failed validation.

This is logged server-side but NOT exposed to clients.

pub fn with_summary(self, summary: impl Into<String>) -> Self

Set a summary message for logging.

pub fn with_debug_info(self, debug_info: DebugInfo) -> Self

Add debug information.

This information will only be included in the response when debug mode is enabled (via enable_debug_mode()).

pub fn is_empty(&self) -> bool

Check if there are no errors.

pub fn len(&self) -> usize

Get the number of errors.

pub fn iter(&self) -> impl Iterator<Item = &ValidationError>

Get an iterator over the errors.

pub fn to_log_string(&self) -> String

Log the error details (for server-side logging).

This returns a formatted string suitable for logging that includes the error details and response content (if any).

Trait Implementations

impl Clone for ResponseValidationError

fn clone(&self) -> ResponseValidationError

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ResponseValidationError

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

Formats the value using the given formatter.

impl Default for ResponseValidationError

fn default() -> ResponseValidationError

Returns the “default value” for a type.

impl Display for ResponseValidationError

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

Formats the value using the given formatter.

impl Error for ResponseValidationError

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 ResponseValidationError

fn into_response(self) -> Response

Convert into a response.