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Types ¶
type CallWrapper ¶
A constructor for a piece of middleware. Some middleware use this constructor out of the box, so in most cases you can just pass somepackage.New
type Chain ¶
type Chain struct {
// contains filtered or unexported fields
}
Chain acts as a list of http.Handler middlewares. Chain is effectively immutable: once created, it will always hold the same set of middlewares in the same order.
func New ¶
func New(wrappers ...CallWrapper) Chain
New creates a new chain, memorizing the given list of middleware middlewares. New serves no other function, middlewares are only called upon a call to Then().
func (Chain) Append ¶
func (c Chain) Append(wrappers ...CallWrapper) Chain
Append extends a chain, adding the specified middlewares as the last ones in the request flow.
Append returns a new chain, leaving the original one untouched.
stdChain := alice.New(m1, m2) extChain := stdChain.Append(m3, m4) // requests in stdChain go m1 -> m2 // requests in extChain go m1 -> m2 -> m3 -> m4
func (Chain) Extend ¶
Extend extends a chain by adding the specified chain as the last one in the request flow.
Extend returns a new chain, leaving the original one untouched.
stdChain := alice.New(m1, m2) ext1Chain := alice.New(m3, m4) ext2Chain := stdChain.Extend(ext1Chain) // requests in stdChain go m1 -> m2 // requests in ext1Chain go m3 -> m4 // requests in ext2Chain go m1 -> m2 -> m3 -> m4
Another example:
aHtmlAfterNosurf := alice.New(m2)
aHtml := alice.New(m1, func(h http.Handler) http.Handler {
csrf := nosurf.New(h)
csrf.SetFailureHandler(aHtmlAfterNosurf.ThenFunc(csrfFail))
return csrf
}).Extend(aHtmlAfterNosurf)
// requests to aHtml hitting nosurfs success handler go m1 -> nosurf -> m2 -> target-handler
// requests to aHtml hitting nosurfs failure handler go m1 -> nosurf -> m2 -> csrfFail
func (Chain) Then ¶
Then chains the middleware and returns the final http.Handler.
New(m1, m2, m3).Then(h)
is equivalent to:
m1(m2(m3(h)))
When the request comes in, it will be passed to m1, then m2, then m3 and finally, the given handler (assuming every middleware calls the following one).
A chain can be safely reused by calling Then() several times.
stdStack := alice.New(ratelimitHandler, csrfHandler) indexPipe = stdStack.Then(indexHandler) authPipe = stdStack.Then(authHandler)
Note that middlewares are called on every call to Then() and thus several instances of the same middleware will be created when a chain is reused in this way. For proper middleware, this should cause no problems.
Then() treats nil as http.DefaultServeMux.
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