Middleware phases - initial implementation
Modify the app and router implementation, so that the middleware is
executed in order defined by phases.
Predefined phases:
'initial', 'session', 'auth', 'parse', 'routes', 'files', 'final'
Methods defined via `app.use`, `app.route` and friends are executed
as the first thing in 'routes' phase.
API usage:
app.middleware('initial', compression());
app.middleware('initial:before', serveFavicon());
app.middleware('files:after', loopback.urlNotFound());
app.middleware('final:after', errorHandler());
Middleware flavours:
// regular handler
function handler(req, res, next) {
// do stuff
next();
}
// error handler
function errorHandler(err, req, res, next) {
// handle error and/or call next
next(err);
}
This commit is contained in:
Miroslav Bajtoš
parent
747da886c9
commit
4e1433b519
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@ -2,7 +2,7 @@
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* Module dependencies.
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*/
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var express = require('express');
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var express = require('./server-app');
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var proto = require('./application');
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var fs = require('fs');
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var ejs = require('ejs');
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@ -0,0 +1,125 @@
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var express = require('express');
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var merge = require('util')._extend;
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var PhaseList = require('loopback-phase').PhaseList;
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var debug = require('debug')('loopback:app');
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var proto = {};
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module.exports = function loopbackExpress() {
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var app = express();
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app.__expressLazyRouter = app.lazyrouter;
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merge(app, proto);
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return app;
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};
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/**
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* Register a middleware handler to be executed in a given phase.
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* @param {string} name The phase name, e.g. "init" or "routes".
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* @param {function} handler The middleware handler, one of
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* `function(req, res, next)` or
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* `function(err, req, res, next)`
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* @returns {object} this (fluent API)
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*/
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proto.middleware = function(name, handler) {
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this.lazyrouter();
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var fullName = name;
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var handlerName = handler.name || '(anonymous)';
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var hook = 'use';
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var m = name.match(/^(.+):(before|after)$/);
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if (m) {
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name = m[1];
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hook = m[2];
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}
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var phase = this._requestHandlingPhases.find(name);
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if (!phase)
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throw new Error('Unknown middleware phase ' + name);
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var wrapper;
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if (handler.length === 4) {
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// handler is function(err, req, res, next)
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debug('Add error handler %j to phase %j', handlerName, fullName);
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wrapper = function errorHandler(ctx, next) {
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if (ctx.err) {
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var err = ctx.err;
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ctx.err = undefined;
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handler(err, ctx.req, ctx.res, storeErrorAndContinue(ctx, next));
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} else {
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next();
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}
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};
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} else {
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// handler is function(req, res, next)
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debug('Add middleware %j to phase %j', handlerName , fullName);
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wrapper = function regularHandler(ctx, next) {
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if (ctx.err) {
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next();
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} else {
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handler(ctx.req, ctx.res, storeErrorAndContinue(ctx, next));
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}
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};
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}
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phase[hook](wrapper);
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return this;
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};
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function storeErrorAndContinue(ctx, next) {
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return function(err) {
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if (err) ctx.err = err;
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next();
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};
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}
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// Install our custom PhaseList-based handler into the app
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proto.lazyrouter = function() {
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var self = this;
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if (self._router) return;
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self.__expressLazyRouter();
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// Storing the fn in another property of the router object
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// allows us to call the method with the router as `this`
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// without the need to use slow `call` or `apply`.
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self._router.__expressHandle = self._router.handle;
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self._requestHandlingPhases = new PhaseList();
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self._requestHandlingPhases.add([
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'initial', 'session', 'auth', 'parse',
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'routes', 'files', 'final'
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]);
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// In order to pass error into express router, we have
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// to pass it to a middleware executed from within the router.
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// This is achieved by adding a phase-handler that wraps the error
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// into `req` object and then a router-handler that unwraps the error
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// and calls `next(err)`.
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// It is important to register these two handlers at the very beginning,
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// before any other handlers are added.
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self.middleware('routes', function wrapError(err, req, res, next) {
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req.__err = err;
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next();
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});
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self.use(function unwrapError(req, res, next) {
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var err = req.__err;
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req.__err = undefined;
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next(err);
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});
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self.middleware('routes', function runRootHandlers(req, res, next) {
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self._router.__expressHandle(req, res, next);
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});
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// Overwrite the original handle() function provided by express,
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// replace it with our implementation based on PhaseList
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self._router.handle = function(req, res, next) {
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var ctx = { req: req, res: res };
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self._requestHandlingPhases.run(ctx, function(err) {
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next(err || ctx.err);
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});
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};
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};
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@ -38,7 +38,7 @@
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"canonical-json": "0.0.4",
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"debug": "~2.0.0",
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"ejs": "~1.0.0",
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"express": "4.x",
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"express": "^4.10.2",
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"inflection": "~1.4.2",
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"loopback-connector-remote": "^1.0.1",
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"nodemailer": "~1.3.0",
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@ -78,6 +78,7 @@
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"karma-script-launcher": "~0.1.0",
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"loopback-boot": "^1.1.0",
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"loopback-datasource-juggler": "^2.8.0",
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"loopback-phase": "^1.0.1",
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"loopback-testing": "~0.2.0",
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"mocha": "~1.21.4",
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"serve-favicon": "~2.1.3",
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@ -90,6 +91,7 @@
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},
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"browser": {
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"express": "./lib/browser-express.js",
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"./lib/server-app.js": "./lib/browser-express.js",
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"connect": false,
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"nodemailer": false
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},
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@ -1,5 +1,5 @@
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var path = require('path');
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var SIMPLE_APP = path.join(__dirname, 'fixtures', 'simple-app');
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var http = require('http');
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var loopback = require('../');
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var PersistedModel = loopback.PersistedModel;
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@ -7,6 +7,102 @@ var describe = require('./util/describe');
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var it = require('./util/it');
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describe('app', function() {
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describe.onServer('.middleware(phase, handler)', function() {
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var app;
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var steps;
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beforeEach(function setup() {
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app = loopback();
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steps = [];
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});
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it('runs middleware in phases', function(done) {
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var PHASES = [
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'initial', 'session', 'auth', 'parse',
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'routes', 'files', 'final'
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];
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PHASES.forEach(function(name) {
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app.middleware(name, namedHandler(name));
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});
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app.use(namedHandler('main'));
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executeHandlers(function(err) {
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if (err) return done(err);
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expect(steps).to.eql([
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'initial', 'session', 'auth', 'parse',
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'main', 'routes', 'files', 'final'
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]);
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done();
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});
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});
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it('supports "before:" and "after:" prefixes', function(done) {
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app.middleware('routes:before', namedHandler('routes:before'));
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app.middleware('routes:after', namedHandler('routes:after'));
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app.use(namedHandler('main'));
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executeHandlers(function(err) {
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if (err) return done(err);
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expect(steps).to.eql(['routes:before', 'main', 'routes:after']);
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done();
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});
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});
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it('injects error from previous phases into the router', function(done) {
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var expectedError = new Error('expected error');
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app.middleware('initial', function(req, res, next) {
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steps.push('initial');
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next(expectedError);
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});
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// legacy solution for error handling
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app.use(function errorHandler(err, req, res, next) {
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expect(err).to.equal(expectedError);
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steps.push('error');
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next();
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});
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executeHandlers(function(err) {
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if (err) return done(err);
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expect(steps).to.eql(['initial', 'error']);
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done();
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});
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});
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it('passes unhandled error to callback', function(done) {
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var expectedError = new Error('expected error');
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app.middleware('initial', function(req, res, next) {
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next(expectedError);
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});
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executeHandlers(function(err) {
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expect(err).to.equal(expectedError);
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done();
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});
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});
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function namedHandler(name) {
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return function(req, res, next) {
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steps.push(name);
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next();
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};
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}
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function executeHandlers(callback) {
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var server = http.createServer(function(req, res) {
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app.handle(req, res, callback);
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});
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request(server)
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.get('/test/url')
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.end(function(err) {
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if (err) return callback(err);
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});
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}
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});
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describe('app.model(Model)', function() {
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var app, db;
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