• Mongoose's Populate Method
• Model / Controller / Routes organization

• cd into your project directory
• npm install to install dependencies
• Run mongod to start your Mongo server from your root directory or create a data directory in this project

For this mini sprint, there are two models we'll be utilizing: the Post model and the Comment model. The Comment model depends upon the Post model. You'll notice that the in the Post model schema we have this line

comments: [{ type: mongoose.Schema.Types.Number, ref: 'Comment' }]

This line specifies the comments field on the Post schema, which is an array populated by comment IDs. This is where the populate() method that Mongoose provides comes in. When we fetch a post, we want to also see all of its associated comments on the posts that we get back from the database. Without running populate(), our posts would come back with an array of just IDs of all of their comment children, without the comments' actual data. Here's an example of running the populate() command

Post.findById(3).exec()
   .then((post) => {
   	post.populate('comments');
   	res.send(post);
   }

Take a look at how the files in this sprint are organized. The model directory holds the schemas. The routes directory specifies all of the routes of our little API. The controller directory holds all of the logic that needs to be executed upon querying individual endpoints.

Think of this style of organization as analogous to the Model / View / Controller paradigm that is still commonly used in front end applications. It's just a way of organizing and modularizing different parts of what our project needs to do in a logical fashion. Organizing your code in this way makes it easier to find files in the future when a project scales and becomes much larger in terms of sheer number of lines of code. Also, a developer without any prior knowledge of the project can look around and orient themselves much more easily with an organization pattern such as this.

• Implement all of the different controller methods in the controllers/postControllers.js file.
• Test your implementation locally on your Mongo server with either Postman, or via your terminal.