#17 - Adding an 'aliases' config section

README.md

@@ -8,7 +8,7 @@
 # express-jefferson
 Declarative Express Application Wiring
 
-express-jefferson is a microlibrary for declaratively describing RESTful services. Currently, it allows you to describe your service routes as a map.
+express-jefferson is a microlibrary for declaratively describing RESTful services.
 
 ```js
 // main.js
@@ -58,6 +58,7 @@ jefferson(app, conf);
 
 ## Configuration
 * routes - An map of routes by name. Each object in the map describes an endpoint to be wired. These endpoints must contain an HTTP method, a path, and an array of middleware functions.
+* aliases: (optional) - A map of alias-name to handler chain. Routes may use these aliases in lieu of repeated function groups.
 * proxies: (optional) - An array of proxy objects invoked around all middleware functions in order. Each proxy object should have an init() function that accepts a delegate middleware function and returns a new middleware function.
 * params: (optional) - A map of path-parameter name to resolver functions. 
 

src/jefferson.js

@@ -40,6 +40,19 @@ module.exports = (app, conf) => {
      * @returns {*} An array of middleware functions
      */
     let configureMiddleware = (middleware) => {
+        for (let i = middleware.length -1; i >= 0; i--) {
+            let item = middleware[i];
+            if (typeof item === 'string') {
+                if (!conf.aliases) {
+                    throw new Error(`no aliases defined, cannot find ${item}`);
+                }
+                if (!conf.aliases[item]) {
+                    throw new Error(`could not find handler chain with alias ${item}`);
+                }
+                let subchain = conf.aliases[item];
+                middleware.splice(i, 1, subchain);
+            }
+        }
         return middleware.map(wrapInProxies);
     };
 

src/jefferson.test.js

@@ -221,4 +221,89 @@ describe('Jefferson', () => {
                 done();
             });
     });
+
+    it('throws if a subchain reference is undefined', () => {
+        let conf = {
+            aliases: {
+                'derp': []
+            },
+            routes: {
+                'getUser': {
+                    method: 'GET',
+                    path: '/test-item',
+                    middleware: [
+                        (req, res, next) => {
+                            req.entity = {id: 1};
+                            next();
+                        },
+                        'processAndReturn'
+                    ]
+                }
+            }
+        };
+
+        let app = express();
+        expect(() => jefferson(app, conf)).to.throw();
+    });
+
+    it('throws if a alias section is undefined and an alias is referenced', () => {
+        let conf = {
+            routes: {
+                'getUser': {
+                    method: 'GET',
+                    path: '/test-item',
+                    middleware: [
+                        (req, res, next) => {
+                            req.entity = {id: 1};
+                            next();
+                        },
+                        'processAndReturn'
+                    ]
+                }
+            }
+        };
+
+        let app = express();
+        expect(() => jefferson(app, conf)).to.throw();
+    });
+
+    it('can reference subchain aliases', (done) => {
+        let conf = {
+            aliases: {
+                processAndReturn: [
+                    (req, res, next) => {
+                        req.entity.herp = 'derp';
+                        next();
+                    },
+                    (req, res) => { res.json(req.entity); }
+                ]
+            },
+            routes: {
+                'getUser': {
+                    method: 'GET',
+                    path: '/test-item',
+                    middleware: [
+                        (req, res, next) => {
+                            req.entity = {id: 1};
+                            next();
+                        },
+                        'processAndReturn'
+                    ]
+                }
+            }
+        };
+
+        let app = express();
+        jefferson(app, conf);
+
+        request(app)
+            .get('/test-item')
+            .expect(200)
+            .end((err, res) => {
+                if (err) { return done(err); }
+                expect(res.body.id).to.equal(1);
+                expect(res.body.herp).to.equal('derp');
+                done();
+            });
+    });
 });