Module sql_interface_refill

Contains functions for execution of all queries relevant for refill (water) Manages all database interactions for the automated water refill system.

This module provides a dedicated interface, SqlInterfaceRefill, for handling all SQL operations related to the refill event log (refill table). It also defines a DatabaseInterfaceRefillTrait to decouple the core refill logic from the specific database implementation, adhering to the Dependency Inversion Principle.

Key Components

• DatabaseInterfaceRefillTrait: An abstraction that defines the contract for any component that interacts with refill data. This is crucial for testability, as it allows for mock implementations to be used in unit tests without needing a live database.

• SqlInterfaceRefill Struct: The concrete implementation of the trait, holding a database connection and providing methods for all refill-related operations.

• new() Constructor: A critical entry point that performs “fail-fast” validation at initialization. It checks whether the number of rows in the refill table exceeds the max_rows_refill limit defined in the application configuration, preventing uncontrolled table growth.

• Statistics Methods: Functions like get_refill_count_of_last_24h and get_refill_volume_of_last_24h provide aggregated data about recent refill activity.

• insert_refill_event(): The core logging function that persists the details of a completed refill operation to the database.

Design and Purpose

The main goal of this module is to provide a robust, encapsulated, and testable interface for the refill subsystem’s data.

• Encapsulation: All SQL queries and logic specific to the refill table are contained within this module, separating concerns.

• Data Integrity: The constructor’s validation logic enforces the configured row limit at startup, ensuring the system doesn’t start with an overgrown log table.

• Abstraction for Testability: The DatabaseInterfaceRefillTrait allows higher-level components to be tested independently of the database.

Structs

SqlInterfaceRefill

Contains the configuration and the implementation of the SQL interface for Refill.

Traits

DatabaseInterfaceRefillTrait

Trait for interfacing between refill and SQL database This trait is prerequisite to use mock implementation for testing