feat(rest): switch to body parser and add extensibility for parsers

docs/site/Parsing-requests.md

@@ -179,6 +179,86 @@ in/by the `@requestBody` decorator. Please refer to the documentation on
 [@requestBody decorator](Decorators.md#requestbody-decorator) to get a
 comprehensive idea of defining custom validation rules for your models.
 
+We support `json`, `urlencoded`, and `text` content types. The client should set
+`Content-Type` http header to `application/json`,
+`application/x-www-form-urlencoded`, or `text/plain`. Its value is matched
+against the list of media types defined in the `requestBody.content` object of
+the OpenAPI operation spec. If no matching media types is found or the type is
+not supported yet, an UnsupportedMediaTypeError (http statusCode 415) will be
+reported.
+
+Please note that `urlencoded` media type does not support data typing. For
+example, `key=3` is parsed as `{key: '3'}`. The raw result is then coerced by
+AJV based on the matching content schema. The coercion rules are described in
+[AJV type coercion rules](https://github.com/epoberezkin/ajv/blob/master/COERCION.md).
+
+The [qs](https://github.com/ljharb/qs) is used to parse complex strings. For
+example, given the following request body definition:
+
+```ts
+const requestBodyObject = {
+  description: 'data',
+  content: {
+    'application/x-www-form-urlencoded': {
+      schema: {
+        type: 'object',
+        properties: {
+          name: {type: 'string'},
+          location: {
+            type: 'object',
+            properties: {
+              lat: {type: 'number'},
+              lng: {type: 'number'},
+            },
+          },
+          tags: {
+            type: 'array',
+            items: {type: 'string'},
+          },
+        },
+      },
+    },
+  },
+};
+```
+
+The encoded value
+`'name=IBM%20HQ&location[lat]=0.741895&location[lng]=-73.989308&tags[0]=IT&tags[1]=NY'`
+is parsed and coerced as:
+
+```ts
+{
+  name: 'IBM HQ',
+  location: {lat: 0.741895, lng: -73.989308},
+  tags: ['IT', 'NY'],
+}
+```
+
+The request body parser options (such as `limit`) can now be configured by
+binding the value to `RestBindings.REQUEST_BODY_PARSER_OPTIONS`
+('rest.requestBodyParserOptions'). For example,
+
+```ts
+server.bind(RestBindings.REQUEST_BODY_PARSER_OPTIONS).to({
+  limit: '4MB',
+});
+```
+
+The options can be media type specific, for example:
+
+```ts
+server.bind(RestBindings.REQUEST_BODY_PARSER_OPTIONS).to({
+  json: {limit: '4MB'},
+  text: {limit: '1MB'},
+});
+```
+
+The list of options can be found in the
+[body-parser](https://github.com/expressjs/body-parser/#options) module.
+
+By default, the `limit` is `1MB`. Any request with a body length exceeding the
+limit will be rejected with http status code 413 (request entity too large).
+
 A few tips worth mentioning:
 
 - If a model property's type refers to another model, make sure it is also

packages/openapi-v3/src/decorators/request-body.decorator.ts

@@ -81,7 +81,9 @@ export function requestBody(requestBodySpec?: Partial<RequestBodyObject>) {
   return function(target: Object, member: string, index: number) {
     debug('@requestBody() on %s.%s', target.constructor.name, member);
     debug('  parameter index: %s', index);
-    debug('  options: %s', inspect(requestBodySpec, {depth: null}));
+    /* istanbul ignore if */
+    if (debug.enabled)
+      debug('  options: %s', inspect(requestBodySpec, {depth: null}));
 
     // Use 'application/json' as default content if `requestBody` is undefined
     requestBodySpec = requestBodySpec || {content: {}};
@@ -95,7 +97,9 @@ export function requestBody(requestBodySpec?: Partial<RequestBodyObject>) {
 
     const paramType = paramTypes[index];
     const schema = resolveSchema(paramType);
-    debug('  inferred schema: %s', inspect(schema, {depth: null}));
+    /* istanbul ignore if */
+    if (debug.enabled)
+      debug('  inferred schema: %s', inspect(schema, {depth: null}));
     requestBodySpec.content = _.mapValues(requestBodySpec.content, c => {
       if (!c.schema) {
         c.schema = schema;
@@ -109,7 +113,9 @@ export function requestBody(requestBodySpec?: Partial<RequestBodyObject>) {
       requestBodySpec[REQUEST_BODY_INDEX] = index;
     }
 
-    debug('  final spec: ', inspect(requestBodySpec, {depth: null}));
+    /* istanbul ignore if */
+    if (debug.enabled)
+      debug('  final spec: ', inspect(requestBodySpec, {depth: null}));
     ParameterDecoratorFactory.createDecorator<RequestBodyObject>(
       OAI3Keys.REQUEST_BODY_KEY,
       requestBodySpec as RequestBodyObject,

packages/rest/package.json

@@ -25,13 +25,14 @@
     "@loopback/http-server": "^1.0.0",
     "@loopback/openapi-v3": "^1.0.2",
     "@loopback/openapi-v3-types": "^1.0.0",
+    "@types/body-parser": "^1.17.0",
     "@types/cors": "^2.8.3",
     "@types/express": "^4.11.1",
     "@types/http-errors": "^1.6.1",
     "@types/parseurl": "^1.3.1",
-    "@types/qs": "^6.5.1",
+    "@types/type-is": "^1.6.2",
     "ajv": "^6.5.1",
-    "body": "^5.1.0",
+    "body-parser": "^1.18.3",
     "cors": "^2.8.4",
     "debug": "^4.0.1",
     "express": "^4.16.3",
@@ -44,6 +45,7 @@
     "path-to-regexp": "^2.2.0",
     "qs": "^6.5.2",
     "strong-error-handler": "^3.2.0",
+    "type-is": "^1.6.16",
     "validator": "^10.4.0"
   },
   "devDependencies": {
@@ -56,7 +58,9 @@
     "@types/js-yaml": "^3.11.1",
     "@types/lodash": "^4.14.106",
     "@types/node": "^10.11.2",
-    "@types/serve-static": "1.13.2"
+    "@types/qs": "^6.5.1",
+    "@types/serve-static": "1.13.2",
+    "@types/type-is": "^1.6.2"
   },
   "files": [
     "README.md",