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58 lines
1.8 KiB
58 lines
1.8 KiB
import {Request} from '../lifecycle/Request'
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import {ResponseObject} from './Route'
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import {Container} from '../../di'
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import {CanonicalItemClass} from '../../support/CanonicalReceiver'
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import {Awaitable, Either, ErrorWithContext, Left, left, Right, right} from '../../util'
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/**
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* Base class representing a middleware handler that can be applied to routes.
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*/
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export abstract class Middleware extends CanonicalItemClass {
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constructor(
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/** The request that will be handled by this middleware. */
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protected readonly request: Request,
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) {
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super()
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if ( !request ) {
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throw new Error('Middleware constructed without request')
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}
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}
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protected container(): Container {
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return this.request
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}
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/**
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* Apply the middleware to the request.
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* If this returns a response factory or similar item, that will be sent
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* as a response.
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*
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* If this returns `void | Promise<void>`, the request will continue to the
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* next handler.
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*/
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public abstract apply(): ResponseObject
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}
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/**
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* A type of Middleware that produces a parameter that is passed to later handlers.
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* Can be used to do common look-ups, &c before routes.
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*/
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export abstract class ParameterMiddleware<T, THandlerArgs extends any[] = []> extends Middleware {
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/** Look up the value. */
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public abstract handle(...options: THandlerArgs): Awaitable<Either<ResponseObject, T>>
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apply(): ResponseObject {
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throw new ErrorWithContext('Attempted to apply parameter-providing middleware directly. Try using `parameterMiddleware()` instead.')
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}
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/** Alias for an error response return. */
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left(what: T): Left<T> {
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return left(what)
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}
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/** Alias for a good value return. */
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right(what: T): Right<T> {
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return right(what)
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}
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}
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