Module middleware 

Middleware system for query interception.

This module provides a flexible middleware system that allows intercepting queries before and after execution. Use cases include:

• Logging - Log all queries and their execution times
• Metrics - Collect query performance metrics
• Caching - Cache query results
• Authentication - Add tenant/user context to queries
• Retry logic - Automatically retry failed queries
• Circuit breaking - Prevent cascade failures

Example

use prax_query::middleware::{Middleware, MiddlewareStack, LoggingMiddleware};

// Create a middleware stack
let mut stack = MiddlewareStack::new();
stack.push(LoggingMiddleware::new());
stack.push(MetricsMiddleware::new());

// Use with an engine
let engine = engine.with_middleware(stack);

Structs

LoggingMiddleware

Middleware that logs queries.

MetricsMiddleware

Middleware that collects query metrics.

MiddlewareBuilder

Builder for creating middleware stacks.

MiddlewareChain

A chain of middleware that processes queries.

MiddlewareStack

A stack of middleware with builder pattern.

Next

The next handler in the middleware chain.

QueryContext

Context passed through the middleware chain.

QueryMetadata

Metadata about a query.

QueryMetrics

Collected metrics for queries.

QueryResponse

Response from a query execution.

RetryConfig

Configuration for retry behavior.

RetryMiddleware

Middleware that automatically retries failed queries.

TimingMiddleware

Middleware that measures query execution time.

TimingResult

Result of timing a query.

Enums

LogLevel

Log level for query logging.

QueryPhase

The current phase of query execution.

QueryType

The type of query being executed.

Traits

MetricsCollector

Interface for collecting metrics.

Middleware

Middleware trait for intercepting queries.

Type Aliases

BoxFuture

A boxed future for async middleware operations.

MiddlewareResult

Result type for middleware operations.