08-07-2019_Week3_Monday

(Create user called newuser and password as 'password')
mysql> CREATE USER 'newuser'@'localhost' IDENTIFIED BY 'password' ;
mysql> GRANT ALL PRIVILEGES ON *.* TO 'newuser'@'localhost' BY 'password';

(creating database called details.)

mysql> CREATE DATABASE details;

mysql> use details

Database changed

(creating a Table called example and coloumn names of firstname , lastname ,email all having intermediate length of 100)

mysql>CREATE TABLE example (firstname VARCHAR(100),lastname VARCHAR(100) ,email VARCHAR(100))

Next task is to get the data from the data base we created .

Creating an spring rest API to communicate through mongoDB and using POSTMAN to check http request.

Softwares used:

• Spring Data Rest
• Spring Boot
• Spring rest API server
• Postman

ref: https://docs.spring.io/spring/docs/2.0.x/reference/jdbc.html

started mongoDB and . Created the called rest_tutorial


> mongo   
> use rest_tutorial
> show dbs (shows the db s in mongo db)
> show collections
> show tables
> db.getCollectionNames() //gets the names of the collection you have
> db.database.find() //displays a list of records matching 

> db.createUser({"user": "ajitesh", "pwd": "gurukul", "roles": ["readWrite", "dbAdmin"]})

(creatinng user called ajitesh with password gurukul )

>db.pets.drop();   (deletes the collection called pets.)

useful to start he mongo server

>sudo service mongod start 
>netstat -plntu (to check whether the port is listening)

usual port of Mongodb is 27017




GET method working
DELETE method working
PUT method working
When POST method working it gave an error

what happened was a simple "/" was missing from the url address

http://localhost:8080/pets wrong
http://localhost:8080/pets/ correct

Connecting Web App to API for calling GET,POST,DELETE

For this we need a client to sent GET,POST,DELETE requests to REST API.

ref: https://spring.io/blog/2009/03/27/rest-in-spring-3-resttemplate

     org.springframework.web.client 


The main problem we come across is what are the steps to connect the webapp to the API server side. 
For this we have couple of methods that can be used.

using http client service HttpClient REST 

http client connection management
http.HttpEntitiy
http.HttpResponse
http.client.HttpClient
http.client.HttpGet
http.impl.client.DefaultHettpClient






RestTemplate supported by Spring

postForLocation  public URI postForLocation(String url, Object request, Object... urlVariables)

getForObject public <T> T getForObject(String url, Class<T> responseType, Object... urlVariables)

delete    public void delete(String url,Object... urlVariables

put public void put(String url,Object request, Object... urlVariables)

String result = restTemplate.getForObject("http://example.com/hotels/{hotel}/bookings/{booking}", String.class,"42", "21");
will perform a GET on http://example.com/hotels/42/bookings/21