refactor to include both get and post in one function

constants.js

@@ -0,0 +1,5 @@
+const COURSES_TABLE = "eg_courses";
+
+module.exports = {
+  COURSES_TABLE
+};

handler.js

@@ -1,14 +0,0 @@
-'use strict';
-
-module.exports.hello = async (event, context) => {
-  return {
-    statusCode: 200,
-    body: JSON.stringify({
-      message: 'Go Serverless v1.0! Your function executed successfully!',
-      input: event,
-    }),
-  };
-
-  // Use this code if you don't use the http event with the LAMBDA-PROXY integration
-  // return { message: 'Go Serverless v1.0! Your function executed successfully!', event };
-};

handlers/courses/index.js

@@ -0,0 +1,38 @@
+const {createResponse} = require('../../helpers');
+const {parseAndValidateBody} = require('../../validators');
+const courseSchema = require('./schema');
+const {COURSES_TABLE} = require('../../constants');
+const db = require('../../services/db');
+
+const get = async (event, context, callback) => {  
+  const courses = await db.scan(COURSES_TABLE);
+
+  return createResponse(200, {
+    courses: courses
+  });
+};
+
+const post = async (event, context, callback) => {
+  const course = await parseAndValidateBody(courseSchema, event.body);
+  const createCourseResult = await db.create(COURSES_TABLE, course);
+
+  return createResponse(200, {
+    course: createCourseResult
+  });
+};
+
+module.exports.default = async (event, context, callback) => {
+  try {
+
+    if (event.httpMethod === "GET") {
+      return get(event, context, callback);
+    }
+    if (event.httpMethod === "POST") {
+      return post(event, context, callback);
+    }
+
+  } catch (err) {
+    const statusCode = (err && err.statusCode) || 500;
+    return createResponse(statusCode, err.message || err);
+  }  
+};

handlers/courses/schema.js

@@ -0,0 +1,13 @@
+module.exports.default = {
+  "type": "object",
+  "properties": {
+    "name": {"type": "string"},
+    "num_tests": {"type": "number"},
+    "num_questions_per_test": {"type": "number"},
+    "answers": {
+      "type": "array",
+      "items": { "type": "string" }
+    }
+  },
+  "required": ["name", "num_tests", "num_questions_per_test", "answers"]
+};

helpers.js

@@ -0,0 +1,20 @@
+const customThrow = (statusCode, message) => {
+  const err = new Error();
+  err.statusCode = statusCode;
+  err.message = message;
+  throw err;
+};
+
+const createResponse = (statusCode, body) => ({
+  statusCode,
+  headers: {
+    "Access-Control-Allow-Origin" : "*", // Required for CORS support to work
+    "Access-Control-Allow-Credentials" : true // Required for cookies, authorization headers with HTTPS
+  },
+  body: JSON.stringify(body),
+});
+
+module.exports = {
+  customThrow,
+  createResponse
+};

serverless.yml

@@ -20,6 +20,17 @@ service: eg-api # NOTE: update this with your service name
 provider:
   name: aws
   runtime: nodejs8.10
+  region: us-east-2
+  iamRoleStatements:
+      - Effect: Allow
+        Action:
+          - dynamodb:Query
+          - dynamodb:Scan
+          - dynamodb:GetItem
+          - dynamodb:PutItem
+          - dynamodb:UpdateItem
+          - dynamodb:DeleteItem
+        Resource: "*"
 
 # you can overwrite defaults here
 #  stage: dev
@@ -55,8 +66,17 @@ provider:
 #    - exclude-me-dir/**
 
 functions:
-  hello:
-    handler: handler.hello
+  courses:
+    handler: handlers/courses.default
+    events:
+      - http:
+          path: courses
+          method: get
+          cors: true
+      - http:
+          path: courses
+          method: post
+          cors: true
 
 #    The following are a few example events you can configure
 #    NOTE: Please make sure to change your handler code to work with those events
@@ -102,3 +122,24 @@ functions:
 #     NewOutput:
 #       Description: "Description for the output"
 #       Value: "Some output value"
+resources:
+  Resources:
+    coursesTable:
+      Type: AWS::DynamoDB::Table
+      Properties:
+        TableName: eg_courses
+        AttributeDefinitions:
+          - AttributeName: name
+            AttributeType: S
+        KeySchema:
+          - AttributeName: name
+            KeyType: HASH
+        Tags:
+          - Key: app
+            Value: ecs-grader
+        ProvisionedThroughput:
+          ReadCapacityUnits: 1
+          WriteCapacityUnits: 1
+
+plugins:
+  - serverless-offline

services/db/dynamoClient.js

@@ -0,0 +1,13 @@
+const AWS = require('aws-sdk');
+
+// Set the region
+AWS.config.update({region: 'us-east-2'});
+
+// also set local endpoint while in development
+if (process.env.NODE_ENV === 'development') {
+  AWS.config.update({endpoint: "http://localhost:8000"});
+}
+
+const client = new AWS.DynamoDB.DocumentClient({});
+
+module.exports = client;

services/db/index.js

@@ -0,0 +1,70 @@
+const dynamoClient = require('./dynamoClient');
+
+const create = async (tableName, item) => {
+  const fullItem = {...item, created_at: Date.now()};
+
+  await dynamoClient.put({
+    TableName: tableName,
+    Item: fullItem
+  }).promise();
+
+  // put does not return saved item, just return our object
+  return fullItem;
+};
+
+const get = async (tableName, keyMap) => {
+  const res = await dynamoClient.get({
+    TableName: tableName,
+    Key: keyMap
+  }).promise();
+
+  return res && res.Item;
+};
+
+const scan = async (tableName) => {
+  const res = await dynamoClient.scan({
+    TableName: tableName
+  }).promise();
+
+  return res && res.Items;
+};
+
+const queryByID = async (tableName, idKeyName, id) => {
+  // querying by id can be used when we are querying a table
+  // that has a sortKey, but we don't need to use the sortKey
+  const res = await dynamoClient.query({
+    TableName: tableName,
+    KeyConditionExpression: "#id = :idValue",
+    ExpressionAttributeNames: {
+      "#id": idKeyName,
+    },
+    ExpressionAttributeValues: {
+      ":idValue": id,
+    }
+  }).promise();
+
+  return res && res.Items;
+};
+
+const update = async (tableName, keyMap, ue, eav) => {
+  const res = await dynamoClient.update({
+    TableName: tableName,
+    Key: keyMap,
+    UpdateExpression: ue,
+    ExpressionAttributeValues: eav,
+    ReturnValues: 'UPDATED_NEW'
+  }).promise();
+
+  console.log('update res', res);
+
+  return res;
+};
+
+module.exports = {
+  client: dynamoClient,
+  create,
+  get,
+  scan,
+  queryByID,
+  update
+};

validators/index.js

@@ -0,0 +1,35 @@
+const Ajv = require('ajv');
+const {customThrow} = require('../helpers');
+
+const parseAndValidateBody = async (schema, body) => {
+  let parsedBody;
+
+  try {
+    parsedBody = JSON.parse(body);
+  } catch (err) {
+    customThrow(400, 'Error. Malformed event.parsedBody.');
+  }
+
+  const validation = validateBody(schema, parsedBody);
+
+  if (!validation.isValid) {
+    customThrow(400, validation.error);
+  }
+
+  return parsedBody;
+};
+
+const validateBody = (schema, body) => {
+  const ajv = new Ajv({$data: true});
+  const validate = ajv.compile(schema);
+  const isValid = validate(body);
+
+  return {
+    isValid: isValid,
+    error: JSON.stringify(validate.errors)
+  }
+};
+
+module.exports = {
+  parseAndValidateBody,
+};