Initial release, parse-server, 2.0.0

PromiseRouter.js

@@ -0,0 +1,148 @@
+// A router that is based on promises rather than req/res/next.
+// This is intended to replace the use of express.Router to handle
+// subsections of the API surface.
+// This will make it easier to have methods like 'batch' that
+// themselves use our routing information, without disturbing express
+// components that external developers may be modifying.
+
+function PromiseRouter() {
+  // Each entry should be an object with:
+  // path: the path to route, in express format
+  // method: the HTTP method that this route handles.
+  //   Must be one of: POST, GET, PUT, DELETE
+  // handler: a function that takes request, and returns a promise.
+  //   Successful handlers should resolve to an object with fields:
+  //     status: optional. the http status code. defaults to 200
+  //     response: a json object with the content of the response
+  //     location: optional. a location header
+  this.routes = [];
+}
+
+// Global flag. Set this to true to log every request and response.
+PromiseRouter.verbose = process.env.VERBOSE || false;
+
+// Merge the routes into this one
+PromiseRouter.prototype.merge = function(router) {
+  for (var route of router.routes) {
+    this.routes.push(route);
+  }
+};
+
+PromiseRouter.prototype.route = function(method, path, handler) {
+  switch(method) {
+  case 'POST':
+  case 'GET':
+  case 'PUT':
+  case 'DELETE':
+    break;
+  default:
+    throw 'cannot route method: ' + method;
+  }
+
+  this.routes.push({
+    path: path,
+    method: method,
+    handler: handler
+  });
+};
+
+// Returns an object with:
+//   handler: the handler that should deal with this request
+//   params: any :-params that got parsed from the path
+// Returns undefined if there is no match.
+PromiseRouter.prototype.match = function(method, path) {
+  for (var route of this.routes) {
+    if (route.method != method) {
+      continue;
+    }
+
+    // NOTE: we can only route the specific wildcards :className and
+    // :objectId, and in that order.
+    // This is pretty hacky but I don't want to rebuild the entire
+    // express route matcher. Maybe there's a way to reuse its logic.
+    var pattern = '^' + route.path + '$';
+
+    pattern = pattern.replace(':className',
+                              '(_?[A-Za-z][A-Za-z_0-9]*)');
+    pattern = pattern.replace(':objectId',
+                              '([A-Za-z0-9]+)');
+    var re = new RegExp(pattern);
+    var m = path.match(re);
+    if (!m) {
+      continue;
+    }
+    var params = {};
+    if (m[1]) {
+      params.className = m[1];
+    }
+    if (m[2]) {
+      params.objectId = m[2];
+    }
+
+    return {params: params, handler: route.handler};
+  }
+};
+
+// A helper function to make an express handler out of a a promise
+// handler.
+// Express handlers should never throw; if a promise handler throws we
+// just treat it like it resolved to an error.
+function makeExpressHandler(promiseHandler) {
+  return function(req, res, next) {
+    try {
+      if (PromiseRouter.verbose) {
+        console.log(req.method, req.originalUrl, req.headers,
+                    JSON.stringify(req.body, null, 2));
+      }
+      promiseHandler(req).then((result) => {
+        if (!result.response) {
+          console.log('BUG: the handler did not include a "response" field');
+          throw 'control should not get here';
+        }
+        if (PromiseRouter.verbose) {
+          console.log('response:', JSON.stringify(result.response, null, 2));
+        }
+        var status = result.status || 200;
+        res.status(status);
+        if (result.location) {
+          res.set('Location', result.location);
+        }
+        res.json(result.response);
+      }, (e) => {
+        if (PromiseRouter.verbose) {
+          console.log('error:', e);
+        }
+        next(e);
+      });
+    } catch (e) {
+      if (PromiseRouter.verbose) {
+        console.log('error:', e);
+      }
+      next(e);
+    }
+  }
+}
+
+// Mount the routes on this router onto an express app (or express router)
+PromiseRouter.prototype.mountOnto = function(expressApp) {
+  for (var route of this.routes) {
+    switch(route.method) {
+    case 'POST':
+      expressApp.post(route.path, makeExpressHandler(route.handler));
+      break;
+    case 'GET':
+      expressApp.get(route.path, makeExpressHandler(route.handler));
+      break;
+    case 'PUT':
+      expressApp.put(route.path, makeExpressHandler(route.handler));
+      break;
+    case 'DELETE':
+      expressApp.delete(route.path, makeExpressHandler(route.handler));
+      break;
+    default:
+      throw 'unexpected code branch';
+    }
+  }
+};
+
+module.exports = PromiseRouter;