Library featuring a command handler pattern for both synchronous and asynchronous operations.
Uses a functional Result approach for failure-prone operations.
To utilize all features using Autofac is required.
Features
Synchronous and asynchronous command handler definitions
Definitions and base implementations of commands
Supports decorators and adapters via Autofac's methods
Description
There are two command types - one that only returns a Result and one that returns an additional entity contained within the Result.
Every handler must return a Result struct which determines whether the operation succedeed or not, handlers may or may not return additional results contained within the Result struct - this is defined by the handled comand.
Installation
To register handlers with the DI container use the ContainerBuilder or IServiceCollection extension methods provided by the library:
builder.AddResultCommander(assembliesToScan);
To register decorators or adapters use the methods available on ResultCommanderConfiguration like so:
<b> You should never throw exceptions from within handlers, they should be exception free - instead return appropriate error results (and catch possible exceptions).</b> Library offers a simple error catching, logging and exception to result error decorators for uses where writing try-catch blocks becomes a pain - but remember that these results will never be as informative as manually returned proper result error types.
A command without a concrete result:
public record SimpleCommand(bool IsSuccess) : ICommand;
And a synchronous handler that handles it:
public class SimpleSyncCommandHandler : ISyncCommandHandler<SimpleCommand>
{
public Result Handle(SimpleCommand command)
{
if (command.IsSuccess)
return Result.FromSuccess();
return new InvalidOperationError();
}
}
A command with a concrete result:
public record SimpleCommandWithConcreteResult(bool IsSuccess) : ICommand<int>;
And an asynchronous handler that handles it:
public SimpleAsyncCommandHandlerWithConcreteResult : IAsyncCommandHandler<SimpleCommand, int>
{
public async Task<Result<int>> Handle(SimpleCommand command)
{
if (command.IsSuccess)
return 1;
return new InvalidOperationError();
}
}
