Databases, Collections, and Documents

In the section before, you connected to the database for this course.

Database-> Collections -> Documents

Each Database and Collection define a namespace.

🤓 Exploring Datasets in Compass

You will use the schema view Compass provides, that will show you a list of the fields, the data types, and a summary of the range of values for each field.

📌 Documents Scalar Value Types

Array, document, special value types (dates, maps)

A field can have multiple value types.

At compass, you can visualize the range of values. For dates, you can see them for days and hours.

📌 MongoDB Documents: Fields with Documents as Values

Using nested documents can help you model your database with a hierarchical data structure.

📌 MongoDb Documents: Fields with Arrays as Values

An array is a good choice when you need data that is a list.

📌 MongoDb Documents: Geospatial Data

There is a type called “Point” where you can store a variety of shapes, calculate the distance between points and filter documents with a specific radius.

🤓 Filtering Collections with Queries

At compass, if you click on a graph element, you’ll activate the filter functionality, and the filter element in the view will be updated.

1. JSON documents start and end with {}

2. JSON documents are composed of fields.

3. Fields have two parts: A key and a value.

   • The key is the name of the field.

   • The value is the value we want to filter with.

📌 Equality filter

{"field_name": "desired match"}

📌 Range filter

$gte, greater than or equal to; $lt, less than

{"field_name": {"$gte":"value", "$lt": "value"}}

🤓 Understanding of JSON

JSON: Javascript Object Notation.

JSON object and JSON document are the same in MongoDB.

JSON objects are analogous to objects, structs, dictionaries in other programming languages.

📌 Rules:

• All the keys have double quotes around them.

• Keys and values must be separated by colons.

• Fields are separated from one to another with commas.

• JSON values can be strings, numbers, boolean, null, array, and objects.