Result<T>

API Reference / SampleApi / Result

Class public

Encapsulates the outcome of a domain operation as either a success carrying a value of type T, or a failure carrying an error message.

Namespace SampleApi

Assembly SampleApi

Package v1.0.0.0

Definition

public class Result<T>

T

Type Parameters

T

The type of the value returned on success.

Remarks

Result`1 implements the discriminated-result pattern: callers inspect IsSuccess (or IsFailure) before accessing Value or Error. Accessing Value on a failed result returns default for T. Prefer the static factory methods Ok(`0) and String) over direct construction to ensure the success/error invariants are satisfied. This type can be used as a method return value in service layers to avoid throwing exceptions for expected failure conditions.

Properties4

Error nullable

string?

string? Result<T>.Error

Gets the error message describing why the operation failed.

IsFailure

bool

bool Result<T>.IsFailure

Gets a value indicating whether the operation failed.

IsSuccess

bool

bool Result<T>.IsSuccess

Gets a value indicating whether the operation succeeded.

Value nullable

T?

T? Result<T>.Value

Gets the value produced by a successful operation.

Methods2

Fail static

Result<T>

Result<T> Result<T>.Fail(
    string error)

Creates a failed result with the specified error message.

Parameters

error string

A message describing the failure.

Returns

Result<T> A Result`1 representing a failed outcome.

Ok static

Result<T>

Result<T> Result<T>.Ok(
    T value)

Creates a successful result containing the specified value.

Parameters

value T

The success value.

Returns

Result<T> A Result`1 representing a successful outcome.

Examples

Using Result to handle success and failure paths:

Result<Customer> result = await customerService.TryFindAsync(id);

if (result.IsSuccess)
{
    Console.WriteLine($"Found: {result.Value!.FullName}");
}
else
{
    Console.WriteLine($"Error: {result.Error}");
}

Returning a Result from a service method:

public Result<Customer> Validate(Customer customer)
{
    if (string.IsNullOrWhiteSpace(customer.FullName))
        return Result<Customer>.Fail("Full name is required.");

    return Result<Customer>.Ok(customer);
}

See Also

ValidationError ProblemDetails