Lesli::Courier

The Lesli::Courier module is a dynamic service caller designed to streamline interactions with service classes within a Ruby on Rails application. By enabling dynamic resolution of modules, services, and methods, Lesli::Courier simplifies complex service calls into a clean and fluent interface.

Why Use Lesli::Courier?

1. Dynamic Module and Service Resolution: Avoid hardcoding module and service names, making the codebase more flexible and easier to maintain.
2. Fluent Interface: Create service calls with a readable, chainable syntax.
3. Error Handling: Optional support for handling undefined modules, services, or methods gracefully.
4. Improved Readability: Reduce boilerplate code and make service interactions more concise.

How It Works

The Lesli::Courier module dynamically:

1. Resolves the module name (e.g., :lesli_test becomes LesliTest).
2. Identifies the service class within the module (e.g., :ticket_service becomes TicketService).
3. Calls the specified method on the service class, optionally passing arguments.

Key Methods

initialize(module_name, on_error = nil)

• Purpose: Sets the module name to resolve and an optional error handler.
• Parameters:
  • module_name (Symbol/String): The module to resolve.
  • on_error (Object, optional): A fallback value to return if an error occurs (normally if the module is not installed or a method is not defined in the required engine).
• Example:

    Lesli::Courier.new(:lesli_test)

from(service_name)

• Purpose: Specifies the service class within the module.
• Parameters:
  • service_name (Symbol/String): The name of the service class.
• Example:

    Lesli::Courier.new(:lesli_test).from(:ticket_service)

with(*args)

• Purpose: Passes arguments to the service class initializer or the method to be called.
• Parameters:
  • args: Arguments to be passed.
• Example:

    Lesli::Courier.new(:lesli_test).from(:ticket_service).with(current_user, query)

call(method_name)

• Purpose: Specifies the method to be called on the service class and triggers the call.
• Parameters:
  • method_name: (Symbol/String): The method to call.
• Example:

    Lesli::Courier.new(:lesli_test).from(:ticket_service).call(:index)

Error Handling

If any part of the process fails (e.g., the module, service class, or method is not found), Lesli::Courier will return the value specified in the on_error parameter (if provided). Otherwise, it will raise an error.

Usage Examples

Basic Usage

# Call the `index_with_deadline` method on the `TicketService` class within the `LesliTest` module
Lesli::Courier.new(:lesli_test)
              .from(:ticket_service)
              .call(:index_with_deadline)

Passing Arguments

# Call the `index` method on the `TicketService` class, passing arguments
Lesli::Courier.new(:lesli_test)
              .from(:ticket_service)
              .with(current_user, query)
              .call(:index)

Custom Error Handling

# Return a custom error object if the service or method is not found
Lesli::Courier.new(:lesli_test, []).from(:ticket_service).call(:non_existent_method)

Note: In the event of an error, Lesli::Courier will always return false instead of raising an exception.