Result

class Result<T>

A discriminated union that encapsulates a successful outcome with a value of type T or a failure with an arbitrary Throwable exception.

Properties

isFailure

isFailure: boolean

Returns true if this instance represents a failed outcome. In this case isSuccess returns false.

isSuccess

isSuccess: boolean

Returns true if this instance represents a successful outcome. In this case isFailure returns false.

Methods

exceptionOrNull

exceptionOrNull(): Throwable | null

Returns the encapsulated Throwable exception if this instance represents failure or null if it is success.

failure

static failure<T>(exception: Throwable): Result<T>

Returns an instance that encapsulates the given Throwable as failure.

fold

fold<R>(
  onSuccess: (value: T) => R,
  onFailure: (exception: Throwable) => R
): R

Returns the result of onSuccess for the encapsulated value if this instance represents success or the result of onFailure function for the encapsulated Throwable exception if it is failure.

Note, that this function rethrows any Throwable exception thrown by onSuccess or by onFailure function.

getOrDefault

getOrDefault(defaultValue: T): T

Returns the encapsulated value if this instance represents success or the defaultValue if it is failure.

getOrElse

getOrElse(onFailure: (exception: Throwable) => T): T

Returns the encapsulated value if this instance represents success or the result of onFailure function for the encapsulated Throwable exception if it is failure.

Note, that this function rethrows any Throwable exception thrown by onFailure function.

getOrNull

getOrNull(): T | null

Returns the encapsulated value if this instance represents success or null if it is failure.

getOrThrow

getOrThrow(): T

Returns the encapsulated value if this instance represents success or throws the encapsulated Throwable exception if it is failure.

map

map<R>(
  transform: (value: T) => R
): R extends Promise<infer U>
  ? Promise<Result<U>>
  : Result<R>

Returns the encapsulated result of the given transform function applied to the encapsulated value if this instance represents success or the original encapsulated Throwable exception if it is failure.

Note, that this function rethrows any Throwable exception thrown by transform function. See mapCatching for an alternative that encapsulates exceptions.

mapCatching

mapCatching<R>(
  transform: (value: T) => R
): R extends Promise<infer U>
  ? Promise<Result<U>>
  : Result<R>

Returns the encapsulated result of the given transform function applied to the encapsulated value if this instance represents success or the original encapsulated Throwable exception if it is failure.

This function catches any Throwable exception thrown by transform function and encapsulates it as a failure. See map for an alternative that rethrows exceptions from transform function.

onFailure

onFailure(action: (exception: Throwable) => void): Result<T>

Performs the given action on the encapsulated Throwable exception if this instance represents failure. Returns the original Result unchanged.

onSuccess

onSuccess(action: (value: T) => void): Result<T>

Performs the given action on the encapsulated value if this instance represents success. Returns the original Result unchanged.

recover

recover(transform: (exception: Throwable) => T): Result<T>
recover(transform: (exception: Throwable) => Promise<T>): Promise<Result<T>>

Returns the encapsulated result of the given transform function applied to the encapsulated Throwable exception if this instance represents failure or the original encapsulated value if it is success.

Note, that this function rethrows any Throwable exception thrown by transform function. See recoverCatching for an alternative that encapsulates exceptions.

recoverCatching

recoverCatching(transform: (exception: Throwable) => T): Result<T>
recoverCatching(transform: (exception: Throwable) => Promise<T>): Promise<Result<T>>

Returns the encapsulated result of the given transform function applied to the encapsulated Throwable exception if this instance represents failure or the original encapsulated value if it is success.

This function catches any Throwable exception thrown by transform function and encapsulates it as a failure. See recover for an alternative that rethrows exceptions.

success

static success<T>(value: T): Result<T>

Returns an instance that encapsulates the given value as a successful value.

toString

toString(): string

Returns a string Success(v) if this instance represents success where v is a string representation of the value or a string Failure(x) if it is failure where x is a string representation of the exception.