API docs: rest.middlewaresequence | LoopBack Documentation

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MiddlewareSequence class

A sequence implementation using middleware chains

Signature:

export declare class MiddlewareSequence implements SequenceHandler 

Implements: SequenceHandler

Constructors

Constructor	Modifiers	Description
(constructor)(context, invokeMiddleware, options)		Constructor: Injects `InvokeMiddleware` and `InvokeMiddlewareOptions`

Properties

Property	Modifiers	Type
defaultOptions	`static`	InvokeMiddlewareOptions
invokeMiddleware	`readonly`	InvokeMiddleware
options	`readonly`	InvokeMiddlewareOptions

Methods

Method Modifiers Description

Method	Modifiers	Description
handle(context)		Runs the default sequence. Given a handler context (request and response), running the sequence will produce a response or an error. Default sequence executes these groups of middleware: `cors`: Enforces `CORS` - `openApiSpec`: Serves OpenAPI specs - `findRoute`: Finds the appropriate controller method, swagger spec and args for invocation - `parseParams`: Parses HTTP request to get API argument list - `invokeMethod`: Invokes the API which is defined in the Application controller method In front of the groups above, we have a special middleware called `sendResponse`, which first invokes downstream middleware to get a result and handles the result or error respectively. Writes the result from API into the HTTP response (if the HTTP response has not been produced yet by the middleware chain. - Catches error logs it using ‘logError’ if any of the above steps in the sequence fails with an error.

handle(context)

Runs the default sequence. Given a handler context (request and response), running the sequence will produce a response or an error.

Default sequence executes these groups of middleware:

cors: Enforces CORS - openApiSpec: Serves OpenAPI specs - findRoute: Finds the appropriate controller method, swagger spec and args for invocation - parseParams: Parses HTTP request to get API argument list - invokeMethod: Invokes the API which is defined in the Application controller method

In front of the groups above, we have a special middleware called sendResponse, which first invokes downstream middleware to get a result and handles the result or error respectively.

Writes the result from API into the HTTP response (if the HTTP response has not been produced yet by the middleware chain. - Catches error logs it using ‘logError’ if any of the above steps in the sequence fails with an error.