SG.NullableExtensions 0.1.0

Nullable Extensions

This is a set of extension methods for C# nullable types (reference types and Nullable<T>) that allow you to ger rid of null checks using if statements and ternary operators. This draws inspiration from Rust.

Methods

• Inspect
• WhenNull
• Is
• Map
• ValueOr

Inspect

The Inspect() methods performs an action against the value if the value is not null.

var product = products.FirstOrDefault(p => p.Code == Code);
product.Inspect(product => product.UpdatedDate = DateTime.NowUtc);

In addition to that Inspect() has async overloads.

var delivery = await delivery.GetProductAsync(id);
product.InspectAsync(p => {
    p.Address = await addressService.GetByPostalCodeAsync(p.PostlCode)
});

Some of the overloads actually extend the ValueTask<T> class, so instead of inspecting a task they inspect the output of the task:

await serializer.SerializeAsync()
    .InspectAsync(message => processor.ProcessAsync(message));

await serializer.SerializeAsync()
    .InspectAsync(message => logger.LogInformation(message));

WhenNull

This method as opposed to Inspect() call the delegate when the value is null.

await serializer.Serialize()
    .WhenNull(message => logger.LogError("Failed to serialize message!"));

Since Inspect() and WhenNull() return the unchanged value you can combine these methods:

await serializer.Serialize()
    .WhenNull(() => logger.LogError("Failed to serialize message!"))
    .Inspect(message => logger.LogInformation(message))
    .Inspect(message => processor.Process(message));

WhenNull() has the same set of async overloads as Inspect().

await serializer.SerializeAsync()
    .WhenNullAsync(() => logger.NotifyAsync("Failed to serialize a message!"));
});

await serializer.SerializeAsync()
    .WhenNullAsync(() => logger.LogError("Failed to serialize a message!"));

await serializer.Serialize()
    .WhenNullAsync(() => notifier.NotifyAsync("Failed to serialize message!"));

Is

Checks if the underlying value is not null. If so, it'll run specified predicate.

var user = userService.GetUser(id);
user.Is(u => u.EmailAddress == emailAddress);

Also, async overloads available.

var user = userService.GetUser(id);
user.IsAsync(u => userOrderService.HasPendingOrdersAsync(u.Id));

userService.GetUserAsync(id).IsAsync(u => userOrderService.HasPendingOrdersAsync(u.Id));

Map

Transforms the underlying value if it is not null.

var user = dbContext.User.FirstOrDefaultAsync(u => u.Id == id)
    .MapAsync(u => new UserModel(u));

ValueOr

Tries to unwrap the underlying value. If the value is null, it will return specified default value.

var address = employee.Address.ValueOr(new Address());

Also, there is an overload that uses a factory instead of plain value.

var address = employee.Address.ValueOr(() => addressService.GetDefaultAddress());

Async overloads are available as well.