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Instance Method

guard(_:else:)

Guards that the future’s value satisfies the callback’s condition or fails with the given error.
func `guard`(_ callback: @escaping (Value) -> Bool, else error: @autoclosure @escaping () -> any Error) -> EventLoopFuture<Value>

Parameters

callback

Callback that asynchronously executes a condition.

error

The error to fail with if condition isn’t met.

Return Value

A future containing the original future’s result.

Discussion

Example usage:

future.guard({ $0.userID == user.id }, else: AccessError.unauthorized)

See Also

EventLoopFuture

  • EventLoopFutureQueue
    Allows you to queue closures that produce an EventLoopFuture, so each future only gets run if the previous ones complete, succeed, or fail.
  • mapEach(_:)
    Gets the value of a key path for each element in the sequence that is wrapped by an EventLoopFuture.
  • mapEach(_:)
    Calls a closure on each element in the sequence that is wrapped by an EventLoopFuture.
  • mapEachCompact(_:)
    Gets the optional value of a key path for each element in the sequence that is wrapped by an EventLoopFuture.
  • mapEachCompact(_:)
    Calls a closure, which returns an Optional, on each element in the sequence that is wrapped by an EventLoopFuture.
  • mapEachFlat(_:)
    Gets the collection value of a key path for each element in the sequence that is wrapped by an EventLoopFuture, combining the results into a single result collection.
  • mapEachFlat(_:)
    Calls a closure which returns a collection on each element in the sequence that is wrapped by an EventLoopFuture, combining the results into a single result collection.
  • flatMapEach(on:_:)
    Calls a closure, which returns an EventLoopFuture, on each element in a sequence that is wrapped by an EventLoopFuture. No results from each future are expected.
  • flatMapEach(on:_:)
    Calls a closure, which returns an EventLoopFuture, on each element in a sequence that is wrapped by an EventLoopFuture.
  • flatMapEachCompact(on:_:)
    Calls a closure, which returns an EventLoopFuture<Optional>, on each element in a sequence that is wrapped by an EventLoopFuture.
  • flatMapEachThrowing(_:)
    Calls a closure on each element in the sequence that is wrapped by an EventLoopFuture.
  • flatMapEachCompactThrowing(_:)
    Calls a closure, which returns an Optional, on each element in the sequence that is wrapped by an EventLoopFuture.
  • sequencedFlatMapEach(_:)
    An overload of sequencedFlatMapEach(_:) which returns a Void future instead of [Void] when the result type of the transform closure is Void.
  • sequencedFlatMapEach(_:)
    A variant form of flatMapEach(on:_:) which guarantees:
  • sequencedFlatMapEachCompact(_:)
    Variant of sequencedFlatMapEach(_:) which provides compactMap() semantics by allowing result values to be nil. Such results are not included in the output array.