notes.md

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6-1: Introduction to Mongoose

Object Data Modeling(ODM) library for MongoDB. It is used for storing data in MongoDB in a structured and developer-friendly way efficiently.

overview -

• It provides a higher-level abstraction for interacting with MongoDB, making it easier to work with data.
• Schemas, models, and relationships can be defined for MongoDB documents.

key features -

• Schema definition
• Model creating
• Data validation
• Querying
• Middleware support
• Population

$$ MongoDB + ODM + ExtraFeatures = Mongoose $$

How Mongoose works with Typescript -

$$ Interface → Schema → Model → DatabaseQuery $$

6-2: Install express, typescript, mongoose, ts-node-dev

Steps to installing MongoDB -

1. press win key

2. type env, go to → “Edit the system environment variables”

3. This will open a new window → “System properties”

4. under the “Advanced” tab click “Environment variables”.

5. This will open a new window → “Environment variables”.

6. Under “User variable for [username]” click on “Path” and after that click on “Edit”

7. This will open a new window “Edit environment variable”

8. Click on the “New” button. Which will open a new line on the list.

9. Now paste the bin directory, which should look like this, C:\Program Files\MongoDB\Server\6.0\bin

10. make sure you ended the path with a \ at the end, like this, C:\Program Files\MongoDB\Server\6.0\bin\

11. You are almost done. Press “OK” → “OK” → “OK”

Hurray! 🎉 The setup is finished. Now you can type mongos --version or mongod --version on your terminal and check your MongoDB. If it shows something like this,

db version v6.0.5
Build Info: {
    "version": "6.0.5",
    "gitVersion": "c9a99c120371d4d4c52cbb15dac34a36ce8d3b1d",
    "modules": [],
    "allocator": "tcmalloc",
    "environment": {
        "distmod": "windows",
        "distarch": "x86_64",
        "target_arch": "x86_64"
    }
}

It means everything is OK.

MongoDB compass local connection string - mongodb://localhost:27017

• setting up the server
  • npm i typescript ts-node-dev @types/express @types/cors --save-dev (Dev dependency)
  • npm i express mongoose cors (dependency)

6-3: How to organize your code a little more. Install and implement types.

types -

• app: *Application*
• *req*: *Request*
• *res*: *Response*
• *next*: *NextFunction*

6-4: How To relate Interface and schema

You have to be responsible for checking if the interface matches with the schema. Cause TS will not give you an error if you leave any field.

6-5: Create a Model using Interface, Schema, and Insert Data

creating a model and Inserting it on save.

6-6: How to organize your structure, MVC vs Modular

MVC

moduler

6-7: More Refactoring, Test API to insert data

$$ Route → controller → service $$

6-8: Create and Test Post Route, Refactor Code

6-9: Find, FindOne, Field Filtering

• Field Filtering

User.findOne({ id: payload }, { _id: 0, name: 1 });

returns the object with only name property.

6-10: What are instance methods, built custom instance method

• Instance method or build-in instance method

  • methods of instance.

    If we create an instance from a class and that instance has a method attached to it, it’s called instance methods

    export const createUserToDB = async (payload: IUser): Promise<IUser> => {
      const user = new User(payload); // User is a class. user is an instance
      await user.save();              // user.save() is a method of user instance. So save() is an instance method
      return user;
    };
    
    // save() is a method of Mongoose. So save() is a build in an instance method.

• Custom instance methods

  Instance methods made by the developer.

  How to create a custom instance method -

  1. Create an interface for the method. go to code
  2. Create a new Model type that knows about the interface. go to code
  3. and add the method to the schema. go to code
  4. Now it can be accessed if you create an Instance. go to code

Now, the instance methods can only be accessed after creating an instance. Not before. Here come static methods so we can use them without creating an instance.

6-11: What is statics, built custom static method

• Static methods -
  • The methods that are attached to the class. We can call these methods without creating an instance. By using class directly. Just like OOP static methods concept. go to notes