Bookmark service (MongoDB & Spring REST) -2/2

    I accidentally deleted my development VM. I got lucky having the habit of taking notes. This blog is useful. Development VM is doom to be lost. Rebuild it waste time, but having a clean slate is refreshing~. What concerns me more is my AWS free quota this month is reaching 85%. The second VM I launched but never being used might be the one to blame. (Of course, my mistake.) I terminated the wrong VM. Now I got Linux 2 built. Great, just threw away everything happened on AMI. 

1st layer: Page

Page class

 

Originally, I need to prepare getter/setter for all class properties for Spring. By using lombok, I only need to create constructors. lombok will deal with getter/setter and toString(). But there are chances to call getter/setter, but how? .......Naming convention.... Capitalize the 1st character with the prefix get/set. 

Annotation @Data was used on this class. 

Repository class

Spring Docs: Repository

https://docs.spring.io/spring-data/mongodb/docs/3.0.0.RELEASE/reference/html/#mongodb.repositories.queries

Spring Docs: curdRepository

https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#repositories.core-concepts

Spring Repository handles intuitive implementation. The developers only need to expose (and guess the naming convention) desired functionalities to other classes. The combinations of defaults are about to rewrite query statements. i.e.

curd Repository provides: findBy, countBy, deleteBy, etc.

Repository provides: containing, like, not in, regex, etc.

Take Page.title as an example, the possible combination could be: 

findByTitle(), deleteByTitleLike(), countByTitleNotIn(), findByTitleRegex(), etc. 

If you're not happy with Spring's service, you can create your own trouble(I'm kidding) by creating multiple interfaces. 

Controller class

Controller exposes methods to URL. Developers can define the "path" and parameters as wish. There are annotations for REST (@GetMapping, @PostMapping) and for general usage (@RequestMapping). In REST, @GetMapping is using method: GET, @PostMapping is also using method: GET, but functioning as INSERT. @RequestMapping can use method:POST as hidden form, but not applicable to REST. 

My controller is the main body to use Repository instance. Based on Spring's tutorial, Repository's instance was stored here. And other classes use @Autowired reference. 

RepositoryCustom, RepositoryImpl classes

Developers are picky. (Don't take it at the face value.)(Customers are picky. They have the very rights. We have the work. Wonderful! (by all meanings.)) When more sophisticated operations are required, customizing repository functionalities is inevitable. At the earlier version, I didn't use Controller and Spring's sample expose interface to URL directly. The only way to customize process is by extending interface. After resolving extension problems, I still had to deploy Controller since Spring does't handle custom functions even though I put annotation on it. I found maybe I can define functionalities in Controller, like how Spring defines id specific operations. 

The setting of a list property in Page object is intentional. Collection of nested object is real-world requirement. No one want to repeatedly typing the entire list only for appending or deleting one item( at Page layer).  And nested objects are stored as references in MongoDB( at Bookmk layer). 

Here are all concepts I thought worth introducing. I learned much from it.