ServiceHook

public protocol ServiceHook

A service hook represents a component that is called at specific events during the processing of a request. A service hook can be attached to a service to e.g. provide caching behavior.


                    
                    
                    onSchedule(_:_:)

Default implementation

The method is called right before a request is scheduled. It may return the result type of a request to prematurely fulfill it. That means, whenever a non-nil value is returned, the request is not sent over the wire but the returned value will be returned instead. No failures can occur after returning a non-nil value here.

Note

When calling schedule(with:) on a request, this method is not guaranteed to be called. If building the URL request fails for some reason (e.g. the body cannot be constructed), no method invocation will occur.

Attention

Internally, the request is actually started to be sent simultaneously with this method call. If the response of this function takes too long, the server’s response might get called. As soon as this method returns, however, the request will be cancelled.

Default Implementation

By default, nil is returned always, allowing the request to be sent to the server.

Declaration

Swift

func onSchedule<R>(_ request: R, _ urlRequest: URLRequest) -> R.Result? where R : Request

Parameters

`request`	The request object that was scheduled.
`urlRequest`	The URL request that would be sent to the server. Contains all headers, the exact body, etc.


                    
                    
                    onSuccess(_:_:result:)

Default implementation

This method is called whenever a request was successfully finished, i.e. a valid response has been recorded from the server. This method will not be called when the result was returned by onSchedule(_:_:).

Default Implementation

By default, no operation is performed.

Declaration

Swift

func onSuccess<R>(_ request: R, _ urlRequest: URLRequest, result: R.Result) where R : Request

Parameters

`request`	The request object that was scheduled.
`urlRequest`	The URL request that was sent to the server.
`result`	The decoded result returned by the server.


                    
                    
                    onFailure(_:)

Default implementation

This method is called whenever a failure occurs when scheduling a Request or a StreamRequest. The error might indicate e.g. network outage that should be displayed to the user.

Default Implementation

By default, no operation is performed.

Declaration

Swift

func onFailure(_ error: Error)

Parameters


                                error

The error that caused a request to fail.