Abhinay-g

> Why agnular forms :
Angualr form gives key-value object of a form which can be used for multiple purpose .
Agnular also give a metadata related to forms.
In traditional HTML form we have action="somefunction()" and method="get!post" , but when we use it with angular we do not specify 
anything to angular, angular itself treat <form> as some kind of directive|compoenent and act on it using formsModule.

> Types of angular forms
Template Driven From : in this template is fixed and form element is accessed on TS {So angular infer form from DOM side}
Reactive Form        : in this form configuration is done on TS file Also on TEMPLATE side {form created dynamically and synced with DOM}

Abhinay-g

> intorductioon 
mongod is a database server , this should be up and running 
mongod --port = PORT will be running mongo server on perticular server
mongo is a mongoDB shell , this is used to do all mongo operation , thought we haave DRIVERS for all kind of platform

Shell command are almost similar as JAVAscript driver for nodejs 

show dbs > show databases 
use DataBase_name > create a database
db.collectionName.insertOne({JSON_Document}) > create a collection and inserting a document into it

Abhinay-g

> Introductions
when working with project we need to find what kind of structure of our data, what will be ralation between our data
We will udnerstand ducuments and other types of data 
we a will also look into diffreent type of relation, And we will Validate the Data [Schema validation]

>Schema 
Mongo DB supposed to be a schemaless DB but why there is a schema, well MongoDB do not enforce schema as 
it is enforced by RELATIONAL database. hance creating a schema is an option and as per developers need
It is totally developer oriented we can follow any approch, we can forefully insert value by assigninign 
null to that extra field

Abhinay-g

> Introduction 
This module based on data creating , Data can be crated on mongodb , or it can be imported from other source 
We will learn about insert method and different ways of importing data into mongo DB 

> Insert methods 
ther eare 3 mthods 
  1 ) insertOne({}) this will take one documetns 
  2 ) insertMany({}) this tail ltake multiple documents 
  3 ) insert() It takes both single/ multiple documents 

Abhinay-g

 >Intorduction 
 This module will consist of following 
 1) methods, Filters and Operators for Reading Data
 2) query selector
 3) Projection operator
 
 >Operators
 All command include a db.collectionName.MethodName({-parameter-})
 parameter can be key value pair or it could be a Range 
 db.collectionName.MethodName({key:{$operator:value}})

Abhinay-g

>$set Operator
this is used to add update an existing field or add a new field
Sysntax : db.collection.updateOne/updateMany({--findQuery--},{$set:{fieldName:"value"}})


> $inc Operator for Increment and Decrement 
this isus ed to increment / decrement the value 
Systax : db.collection.updateOne/updateMany({--findQuery--},{$set:{fieldName:"value"} , $inc:{age: INCREMENT_VALUE}})
Note: $inc can be combined with other operator
IMP : You can not put $set and $inc on same field , it will throw an error ie updating and incrementing age will cause an error 

Abhinay-g

Delete one or many items from collection > db.collection.deleteOne/deleteMany(--findCondition--)
Delete Collection > db.collection.deleteMAny({})
Delete Entire Collection [Admin task]  >>>> db.collection.drop()
Delete entire Database [Admin TAsk]  >>>> db.deleteDatabase()

Abhinay-g

>Introduction
Indexes are to optimize read, update and delete operation.
Indexes load a extra funcnionality while inserting data into DB, mongoDb update indexes whenever a record in inserted
db.contacts.getIndexes() // to get all the indexes

> Why index are needed
By default MongoDB do COLLECTION lookup while read, update and delete operation which is time consuming in sense that 
Thare is unknown number of records that match condition 
records position is unknown to mongoDB , HENCE mongoDB iterate over each document looking for matching condition 
Solution : we can create an index on the column which is frequently used to access records.

Abhinay-g

Introduction:
Aggregation framework is just an alternative for a find method, here there is more controle given to find data in custom format by using 
$match, $sort, $group, $project
This is type of data is only gathered for smaller audiance as we design database based on larger audiance 
In aggregation we create a pipeline where in data of one operator is passed to other operator 

Aggregation method: 
for aggregation we use Aggrigate() method which takes multiple parameter in sequence. Note this aggregation method can take advantage of 
mongodb indexes. 
Note: for this tutorial persons.json is used 

Abhinay-g

referance : https://scotch.io/tutorials/understanding-hoisting-in-javascript

concept: all the declaration of var , let , const , function declaration, class declaration is moved up in run time.
var: variable hoisted and  get (initialized) default value of "undefined" [variable declared without var are added to global scope]
let/ const : variable is hoisted but not assigned to any value
function declaration: function declaration is hoisted to upward.

Note: function and variable with same name then there will be preferance given to variable assignment over but when variable declaration
only then preferance given to function declaration no matter what order they are defined