Toolsfactory.Common Result and Result utility library

The Result and Result<T> classes provide a robust way to represent the outcome of an operation in C#. This approach ensures operations can communicate success, failure, and relevant error details.

Why use Result and Result<T>?

• Clarity:
  • Clearly communicate the outcome of an operation without relying on exceptions.
  • Exceptions are for - as the name already implies - exceptional cases, not for regular control flow.
• Error Handling:
  • Easily access error details when an operation fails.
• Simplicity:
  • Simplify the handling of success and failure scenarios.
  • The code gets more readable and maintainable.
• Performance:
  • Avoid the performance overhead of throwing and catching exceptions.

Key Features

• Encapsulation of Success/Failure:

  • The Result class encapsulates whether an operation was successful or not (IsSuccess).
  • Access to associated errors through the Errors collection.

• Generic Support:

  • The Result<T> class extends Result to include a value (T) when the operation succeeds.

• Immutable Design:

  • Both classes are designed to ensure immutability, enhancing reliability and thread safety.

Class Details

Result

• Indicates whether an operation succeeded (IsSuccess) or failed (IsFaulted).
• Provides a collection of errors (IReadOnlyList<Error>) if the operation fails.
• Constructor overloading allows creating success results or faulted results with error details.

Result<T>

• Extends Result by adding a value (Value) of type T for successful operations.
• Throws an exception if you try to access the Value of a failed operation.
• Ensures Value is cleared upon failure to prevent misuse.

Extension methods

• Switch and Map methods are provided to simplify handling success and failure scenarios.
• Bind, BindTryCatch, and Tap methods are provided to simplify chaining operations following the Railway oriented pattern. (Inspired by this Video)

Usage Examples

Creating a Success Result

var successResult = Result.Success();

Creating a Faulted Result

var faultedResult = Result.Failure(new Error("Operation failed"));

Using Result<T> with a Value

var resultWithValue = Result<int>.Success(42);
if (resultWithValue.IsSuccess)
{
    Console.WriteLine(resultWithValue.Value); // Output: 42
}

Using Result<T> with implicit conversion

record Person(string Name, int Age);
var PersonDB = new List<Person> { new Person("Alice", 25), new Person("Bob", 30) };
var result1 = GetPersonWithName("Alice");
var result2 = GetPersonWithName("James");

Result<Person> GetPersonWithName(string Name)
{
    if (string.IsNullOrWhiteSpace(Name))
    {
        return new Error("Name cannot be empty"); // <= Implicit conversion to Result<Person>
    }
    var person = PersonDB.Where(p => p.Name == Name).FirstOrDefault();
    return person != null ? person : new Error("Person not found"); // <= Implicit conversion to Result<Person>
}

Handling Errors

if (result.IsFaulted)
{
    foreach (var error in result.Errors)
    {
        Console.WriteLine(error.Message);
    }
}

Utility methods

Switch and Map methods are provided to simplify handling success and failure scenarios.

Switch Method

using System;
using System.Collections.Generic;
using Toolsfactory.Common;

class Program
{
    static void Main()
    {
        // Example 1: Success scenario
        var successResult = Result.Success();

        successResult.Switch(
            onSuccess: () => Console.WriteLine("Operation was successful!"),
            onFailure: errors =>
            {
                foreach (var error in errors)
                {
                    Console.WriteLine($"Error: {error.Message}");
                }
            }
        );

        // Example 2: Failure scenario
        var failureResult = Result.Failure(new List<Error>
        {
            new Error("Invalid input"),
            new Error("Connection timeout")
        });

        failureResult.Switch(
            onSuccess: () => Console.WriteLine("Operation was successful!"),
            onFailure: errors =>
            {
                foreach (var error in errors)
                {
                    Console.WriteLine($"Error: {error.Message}");
                }
            }
        );
    }
}

Generic Switch Method

using System;
using System.Collections.Generic;
using Toolsfactory.Common;

class Program
{
    static void Main()
    {
        // Example 1: Success scenario
        var successResult = Result<int>.Success(42);

        successResult.Switch(
            onSuccess: value => Console.WriteLine($"Success! Value: {value}"),
            onFailure: errors =>
            {
                foreach (var error in errors)
                {
                    Console.WriteLine($"Error: {error.Message}");
                }
            }
        );

        // Example 2: Failure scenario
        var failureResult = Result<int>.Failure(new List<Error>
        {
            new Error("Division by zero"),
            new Error("Value out of range")
        });

        failureResult.Switch(
            onSuccess: value => Console.WriteLine($"Success! Value: {value}"),
            onFailure: errors =>
            {
                foreach (var error in errors)
                {
                    Console.WriteLine($"Error: {error.Message}");
                }
            }
        );
    }
}

Map Method

using System;
using System.Collections.Generic;
using Toolsfactory.Common;
class Program
{
    static void Main()
    {
        // Example 1: Success scenario
        var successResult = Result.Success();

        string successMessage = successResult.Map(
            onSuccess: () => "Operation was successful!",
            onFailure: errors => string.Join(", ", errors.Select(e => e.Message))
        );

        Console.WriteLine(successMessage); // Output: Operation was successful!

        // Example 2: Failure scenario
        var failureResult = Result.Failure(new List<Error>
        {
            new Error("Invalid credentials"),
            new Error("Account locked")
        });

        string failureMessage = failureResult.Map(
            onSuccess: () => "Operation was successful!",
            onFailure: errors => string.Join("; ", errors.Select(e => e.Message))
        );

        Console.WriteLine(failureMessage); 
        // Output: Invalid credentials; Account locked
    }
}

Generic Map Method

using System;
using System.Collections.Generic;
using System.Linq;
using Toolsfactory.Common;

class Program
{
    static void Main()
    {
        // Example 1: Success scenario
        var successResult = Result<int>.Success(100);

        string successMessage = successResult.Map(
            onSuccess: value => $"Operation succeeded with value: {value}",
            onFailure: errors => string.Join("; ", errors.Select(e => e.Message))
        );

        Console.WriteLine(successMessage); 
        // Output: Operation succeeded with value: 100

        // Example 2: Failure scenario
        var failureResult = Result<int>.Failure(new List<Error>
        {
            new Error("Network issue"),
            new Error("Timeout occurred")
        });

        string failureMessage = failureResult.Map(
            onSuccess: value => $"Operation succeeded with value: {value}",
            onFailure: errors => $"Errors: {string.Join(", ", errors.Select(e => e.Message))}"
        );

        Console.WriteLine(failureMessage);
        // Output: Errors: Network issue, Timeout occurred
    }
}

Railway oriented pattern samples

Result<string> result = Result<bool>.Success(true)
        .Bind<bool, string>(x => x ? "Great!" : "Not so great...")
        .Tap(Console.WriteLine);