Merge pull request #786 from strongloop/feature/define-middleware-phases

Implement `app.defineMiddlewarePhases`

lib/server-app.js

@@ -54,6 +54,77 @@ proto.middlewareFromConfig = function(factory, config) {
   this.middleware(config.phase, handler);
 };
 
+/**
+ * Register (new) middleware phases.
+ *
+ * If all names are new, then the phases are added just before "routes" phase.
+ * Otherwise the provided list of names is merged with the existing phases
+ * in such way that the order of phases is preserved.
+ *
+ * **Examples**
+ *
+ * ```js
+ * // built-in phases:
+ * // initial, session, auth, parse, routes, files, final
+ *
+ * app.defineMiddlewarePhases('custom');
+ * // new list of phases
+ * // initial, session, auth, parse, custom, routes, files, final
+ *
+ * app.defineMiddlewarePhases([
+ *   'initial', 'postinit', 'preauth', 'routes', 'subapps'
+ * ]);
+ * // new list of phases
+ * // initial, postinit, preauth, session, auth, parse, custom,
+ * // routes, subapps, files, final
+ * ```
+ *
+ * @param {string|Array.<string>} nameOrArray A phase name or a list of phase
+ *   names to add.
+ */
+proto.defineMiddlewarePhases = function(nameOrArray) {
+  this.lazyrouter();
+  if (!Array.isArray(nameOrArray)) {
+    this._requestHandlingPhases.addBefore('routes', nameOrArray);
+    return;
+  }
+
+  var sourcePhases = nameOrArray;
+  if (!sourcePhases.length) return;
+
+  var targetPhases = this._requestHandlingPhases.getPhaseNames();
+  var targetIx = targetPhases.indexOf(nameOrArray[0]);
+
+  if (targetIx === -1) {
+    // the first new phase does not match any existing one
+    // add all phases before "routes"
+    sourcePhases.forEach(function(it) {
+      this._requestHandlingPhases.addBefore('routes', it);
+    }, this);
+    return;
+  }
+
+  // merge (zip) two arrays of phases
+  for (var sourceIx = 1; sourceIx < sourcePhases.length; sourceIx++) {
+    var nameToAdd = sourcePhases[sourceIx];
+    var previousPhase = sourcePhases[sourceIx - 1];
+    var existingIx = targetPhases.indexOf(nameToAdd, targetIx);
+    if (existingIx === -1) {
+      // A new phase - try to add it after the last one,
+      // unless it was already registered
+      if (targetPhases.indexOf(nameToAdd) !== -1) {
+        throw new Error('Phase ordering conflict: cannot add "' + nameToAdd +
+        '" after "' + previousPhase + '", because the opposite order was ' +
+        ' already specified');
+      }
+      this._requestHandlingPhases.addAfter(previousPhase, nameToAdd);
+    } else {
+      // An existing phase - move the pointer
+      targetIx = existingIx;
+    }
+  }
+};
+
 /**
  * Register a middleware handler to be executed in a given phase.
  * @param {string} name The phase name, e.g. "init" or "routes".

test/app.test.js

@@ -146,6 +146,64 @@ describe('app', function() {
     });
   });
 
+  describe.onServer('.defineMiddlewarePhases(nameOrArray)', function() {
+    var app;
+    beforeEach(function() {
+      app = loopback();
+    });
+
+    it('adds the phase just before "routes" by default', function(done) {
+      app.defineMiddlewarePhases('custom');
+      verifyMiddlewarePhases(['custom', 'routes'], done);
+    });
+
+    it('adds an array of phases just before "routes"', function(done) {
+      app.defineMiddlewarePhases(['custom1', 'custom2']);
+      verifyMiddlewarePhases(['custom1', 'custom2', 'routes'], done);
+    });
+
+    it('merges phases preserving the order', function(done) {
+      app.defineMiddlewarePhases([
+        'initial',
+        'postinit', 'preauth', // add
+        'auth', 'routes',
+        'subapps', // add
+        'final',
+        'last' // add
+      ]);
+      verifyMiddlewarePhases([
+        'initial',
+        'postinit', 'preauth', // new
+        'auth', 'routes',
+        'subapps', // new
+        'files', 'final',
+        'last' // new
+      ], done);
+    });
+
+    it('throws helpful error on ordering conflict', function() {
+      app.defineMiddlewarePhases(['first', 'second']);
+      expect(function() { app.defineMiddlewarePhases(['second', 'first']); })
+        .to.throw(/ordering conflict.*first.*second/);
+    });
+
+    function verifyMiddlewarePhases(names, done) {
+      var steps = [];
+      names.forEach(function(it) {
+        app.middleware(it, function(req, res, next) {
+          steps.push(it);
+          next();
+        });
+      });
+
+      executeMiddlewareHandlers(app, function(err) {
+        if (err) return done(err);
+        expect(steps).to.eql(names);
+        done();
+      });
+    }
+  });
+
   describe('app.model(Model)', function() {
     var app, db;
     beforeEach(function() {