yuhang2685 / ITJobWebsite-SpringBoot-MongoDB

Construct an IT Job web service with SpringBoot and MongoDB (Pending functionality to be implemented).

ITJobWebsite-SpringBoot-MongoDB

Construct an IT Job website with SpringBoot and MongoDB.

Author: Dr. Yuhang Zhao

What is MongoDB?

MongoDB is document-DB. Unlike relational database, it does not require creating table before inserting data with pre-defined data structure. With MongoDB we can store data with flexible structures. E.g., JSON-like document.

Install MongoDB from the official website.

Encountered problem: installation never ends on windows 7 X64 bit. Solution: See "Install MongoDB With Compass On Windows" @ https://vegibit.com/install-mongodb-with-compass-on-windows/

Start MongoDB server

Open Command Prompt and navigate to your MongoDB Bin folder, run mongod.exe. Encountered problem: Mongo Server fails to up. Solution: see "How to Install MongoDB on Windows 10" @ https://www.youtube.com/watch?v=FwMwO8pXfq0 Then it will start MongoDB main process and then keep waiting for connections message in the console.

Register MongoDB

Add mongoDB/bin to Path and we can use Mongo Shell and Mongo Server from anywhere.

Construct the app using MongoDB with CRUD functionality through RESTful APIs.

• Create a controller used in RESTful web services to handle HTTP requests and annotated by @RestController.

• Create a service annotated by @Service, which writes business logic in the service layer separated from @RestController.

• Create the entity class for job posting and annotated by @Document. Ref: https://schema.org/JobPosting

• Create the interface repository which extends MongoRepository using the entity class and its Id type.

• Use dependency injection annotated by @Autowired for the repository in service, similarly for service in controller.

• Implement the method to create job postings annotated by @PostMapping. Annotation @RequestBody is used to bind the HTTP request body with a domain object in the method parameter.

• So far we have implemented Create and Read in CRUD. We use PostMan to test the methods.

• Below is what we obtain from Http Get method:

• Add "spring.data.mongodb.database=JobPostings" in application.properties. Thereafter, we use the database "JobPostings" to maintain collections which are corresponding to concept tables in relational DB.

• Implement the method to get a job posting by id, and the method for deleting a job posting by id.

• Implement the method to update a posting by id. First we need to introduce a new class JobPostingNoId which is the JobPosting class but without attribute Id. When calling the method to update a posting, beside the id we also have to supply an object of JobPostingNoId. In this way, we can update a posting except its id. The method returns the updated copy of the posting. Note that although the parameter is of type JobPostingNoId, it doesn't have to supply the complete list of attributes. See the following example.

Response from the method for updating:

That's it! We've implemented all "CRUD" methods. Cheers!

Reference:

• "What is MongoDB? Spring Data MongoDB in Spring Boot Application with Example" by "Tech Primers" @ https://www.youtube.com/watch?v=l5KC6OcbuOI
• "Spring Boot Tutorial - CRUD Operations using MongoDB" by "Code with Kris" @ https://www.youtube.com/watch?v=WT-2KWCa1l8