Last Sync: 2022-08-09 08:30:04

Databases/MongoDB/Introduction.md

@@ -56,6 +56,8 @@ rm /tmp/mongodb-27017.sock
 
 Although Mongo is not a relational database it has a structure that we can understand in relation to that paradigm. A **database** is obviously the overall structure. It comprises **collections** which are organised sets of data that are analagous to [tables](/Databases/Relational_database_architecture.md#table) in RDBs. Within each collection are a series of **documents** which we can think of as being equivalent to [rows](/Databases/Relational_database_architecture.md) in RDB table: units that comprise the collection.
 
+A document is a container comprising key-value pairs in the manner of an object. 
+
 ## Mongoose 
 
 ### Connecting to our database
@@ -72,3 +74,48 @@ mongoose
 ### Creating collections and documents 
 
 In order start adding collections and documents to our database, we use Mongoose's schema structure. (This is specific to the Mongoose wrapper and is not a structure that is a part of Mongo in general.)
+
+We use a schema to define the shape of documents in a MongoDB collection. To do this we instantiate an instance of the Mongoose `Schema` class and set our properties:
+
+#### Creating a schema
+
+```js
+const courseSchema = new mongoose.Schema({
+  name: String,
+  author: String,
+  tags: [String],
+  data: {type: Date, default: Date.now}, // if unspecified, entry will default to current date
+  isPublished: boolean
+});
+
+```
+This is just like defining an interace or type within TypeScript.
+#### Available data types
+
+The following data types are available:
+* `String`
+* `Number`
+* `Boolean`
+* `Array`
+* `Date`
+* `Buffer`
+* `ObjectID` (for UUIDs)
+
+#### Models
+
+Once we have established our schema we can then create a **model** of it. A model is basically a class representation of the interface we define in the schema:
+
+```js
+const Course = mongoose.model("Course", courseSchema);
+```
+With this in place, we can then create instances of the model. This stands in relation to the model as an object does to a class:
+
+```js
+const course = new Course({
+  name: "Node.js Course",
+  author: "Ozzy Osbourne",
+  tags: ["node", "backend"],
+});
+```
+
+// TODO: diagram schema - model - object