MadEyeMatt.Results.AspNetCore 2.0.0

Results

A result object implementation. Return result objects from operations to indicate success or failure instead of throwing exceptions.

Features

• Default result implementations with and without a result value.
  • Result
  • Result<int>
• Supports multiple error messages in a result.
• Supports optional multiple success messages.
• Supports custom result implementations with and without a result value.
  • ResultBase<TResult>
  • ResultBase<TResult, TValue>
• Supports custom error and success implementations.
  • Error
  • Success
• Provides FluentAssertions extensions for simpler uni testing.
• Provides extensions to transform results to IActionResult instances for ASP.NET controllers.
• Provides extensions to transform results to IResult instances to be used with Minimal APIs.

Usage

Create Results

To create result instances use the static helper methods found in the Result and Result<T>classes.

// Create a successful result without a value.
Result result = Result.Ok();

// Create a successful result with a value.
Result<int> result = Result<int>.Ok(42);

// Create a failed result without a value.
Result result = Result.Fail("An error occurred.");
Result result = Result.Fail(new Error("An error occurred));

// Create a failed result for a result that can have a value.
Result<int> result = Result<int>.Fail("An error occurred.");
Result<int> result = Result<int>.Fail(new Error("An error occurred));

The result type Result is typically used by operations that have no return value.

public Result PerformOperation() 
{
    if(this.State == State.Failed) 
    {
        return Result.Fail("The operation failed.");
    }

    return Result.Ok();
}

The result type Result<T> is typically used by operations that have a return value.

public Result<int> PerformOperation() 
{
    if(this.State == State.Failed) 
    {
        return Result<int>.Fail("The operation failed.");
    }

    return Result.Ok(42);
}

Process Results

To process the result of an operation you can check if the operation was successful or failed by accewssing the IsSuccessful and/or IsFailed properties.

// Handle the return value of a result without a value.
Result result = PerformOperation();

// Print all error messages, if the result is failed.
if(result.IsFailed) 
{
    foreach(IError error in result.Errors) 
    {
        Console.WriteLine(error.Message);
    }
}

// Print all success messages, if the result is successful.
if(result.IsSuccessful) 
{
    foreach(ISuccess success in result.Successes) 
    {
        Console.WriteLine(success.Message);
    }
}

// Handle the return value of a result with a value.
Result<int> result = PerformOperation();

// Get the value if the result is successful or will throw if the result is failed.
int value = result.Value;

// Get the value oif the result is successful or will return the default of the value.
int value = result.GetValueOrDefault();

Future

• Store hierarchical error chain in a root error cause.
• Support custom error and success types.

References

Michael Altmann

FluentResults