• The purpose of this exercise is to get you used to being quizzed on Interview Questions commonly asked about Mongo.
• Answers to your written questions will be recorded in Answers.md
• This is to be worked on alone but you can use outside resources. You can reference any old code you may have, and the React Documentation, however, please refrain from copying and pasting any of your answers. Try and understand the question and put your responses in your own words. Be as thorough as possible when explaining something.
• Just a friendly Reminder Don't fret or get anxious about this, this is a no-pressure assessment that is only going to help guide you here in the near future. This is NOT a pass/fail situation.

  Start by forking and cloning this repository.

  Questions - Self Study - You can exercise your Google-Fu for this and any other Sprint Challenge in the future.

1. Describe the following: DataBase, Collection , Document
2. Describe how one can achieve the pattern of relationships in MongoDB. What needs to take place at the schema level? How do we 'fill' in the appropriate relational data using mongoose?
3. Explain a way to break up an API into Sub-Applications, which tool did we use to do that?

• For this Project we're going to be building out a Backend for a Budget Tracker app.

• For this project you'll need three different models, budget, Expense and Category.

• This will be the budget that you set for Budget Tracker.
• An budget object saved to the DB should look like this:

{
  _id: ObjectId('507f1f77bcf86cd799439011'),
  title: 'Budget',
  budgetAmount: 3000,
}

• An expense is a purchase one would make that will affect one's budget.
• There will be two relationships tied to an expense, the budget it effects, & category it belongs to.
• An expense object when saved to the database would look something like this:

{
  _id: ObjectId('503c2b66bcf86cs793443564'),
  amount: 35,
  description: 'potatoes',
  budget: ObjectId('507f1f77bcf86cd799439011'), // Monthly Spending
  category: ObjectId('543d2c72gsb23cd657438921') // Groceries
}

• A category collection will consist of different places you can assign your expenses to.
• A category can be something as simple as groceries.
• Your relationship to consider here is the relationship between Expenses and Categories
• An example of a category object after it is saved to the databse:

{
  _id: ObjectId('543d2c72gsb23cd657438921'),
  title: 'Groceries',
}

Add your code to server.js. Remember to install any npm packages you need.

• Used to save a new budget to the database.

• Only worry about creating ONE budget for now.

• NOTE We only want to create a budget, no need to write a getter or even update the budget total directly. When we call for data to see how much is left in our budget, we'll write a separate endpoint that aggregates that information for us. We want to keep our budget total 'pure' and unaffected by our queries.

• to create a category you should have a 'post' method that stores the category information.
• you can write a getter 'get' method that simply returns all the categories. Filter out any unuseful information here, meaning we just want the title of the categories.
• create a minimum of 4 categories so that when you create your expenses, you can assign where they go!
• example of categories could be: Food/Dining Gas/Auto Date Nights Mortgage

• your expense should have a 'post' method for creating the expense. To save an expense you'll need an 'budget' _id and a 'category' _id so that we can build out a relationship between those other collections and our expenses.
• your expense route should also have a 'get' method that returns all the expenses with the populated data.

You are not required to work on the stretch goal, but if you're done with the main project go ahead an try to figure out how to use MongoDB's Aggregation Framework.

1. Add as many CRUD endpoints as you can and break the application into separate Routers.
2. Validate the data at the endpoint, before saving it to the database.
3. Add a React front end.

Good Luck!