add task description

README.md

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+# Spring Core
+
+### Task
+
+#### Recommended Timeline
+
+The recommended timeline for the whole module is 2 weeks.
+
+#### Business requirements
+
+- Migrate your solution prepared in **Architecture advanced** module to Spring.
+- Support [CRUD](https://en.wikipedia.org/wiki/Create,_read,_update_and_delete) operations for Author as well.
+
+#### Prerequisites
+
+You are provided with the basic interfaces for `repository`, `service` and `controller` layers:
+
+- `com.mjc.school.repository.model.BaseEntity`
+- `com.mjc.school.repository.BaseRepository`
+- `com.mjc.school.service.BaseService`
+- `com.mjc.school.controller.BaseController`
+
+Use them as base point for your solution. Do not change or delete them.
+
+#### DataSource
+
+Domain objects are represented by the following diagram
+
+![](./media/source_model.png "source_model")
+
+and have the following requirements:
+
+- [x] All fields for News (except `authorId`) and Author are required.
+- [x] _Id_ fields should be auto generated.
+- [x] News _title_ field should have length from 5 to 30.
+- [x] News _content_ field should have length from 5 to 255.
+- [x] News and Author _createdDate_, _lastUpdatedDate_ fields should be
+  in [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) format. Example: 2018-08-29T06:12:15.156. More discussion
+  here: [stackoverflow: how to get iso 8601](https://stackoverflow.com/questions/3914404/how-to-get-current-moment-in-iso-8601-format-with-date-hour-and-minute)
+  .
+- [x] News _authorId_ field should be mapped to the author datasource.
+- [x] Author _name_ field should have length from 3 to 15.
+
+As well as in the **Architecture advanced** module data source should be generated automatically at runtime and saved in
+array datasource by reading files from the `resources` folder in the repository module (database emulation).
+
+For example: `author.txt`, `content.txt` which should contain the required data.
+
+#### Operations
+
+The system should expose CRUD operations for News and Author from the __main__ module in the root project:
+
+- [x] Create News - fill only title, content, authorId and return created news.
+- [x] Create Author - fill only name and return created author.
+- [x] Get All News – return list of news.
+- [x] Get All Authors – return list of authors.
+- [x] Get News by id – return news by provided id.
+- [x] Get Author by id – return author by provided id.
+- [x] Update News – update only title, content, authorId by provided news id and return updated news.
+- [x] Update Author – update only name by provided author id and return updated author.
+- [x] Delete News – delete news by provided news id and return boolean value.
+- [x] Delete Author – delete author by provided author id and return boolean value. When deleting author you could
+  choose 2 options:
+    - set `authorId` field for corresponding news to `null`.
+    - remove corresponding news.
+
+  > ##### Optional
+  > Think of declarative way of choosing appropriate option instead of imperative way:
+  >
+  > _**Imperative way:**_ in `delete author` method load all news related to that author and either set their `authorId`
+  > field to `null` or remove them.
+  >
+  > _**Declarative way:**_ use custom annotation (e.g. `@OnDelete`) with its handler (could be implemented
+  > via [Aspects][1]).
+
+As well as in the **Architecture advanced** module all returned and received data should be
+like [DTO](https://en.wikipedia.org/wiki/Data_transfer_object) type.
+
+The mapping between the `dto` and the `model (domain object)` should be done at the service layer using any library. For
+example: [Mapstruct](https://mapstruct.org/), [Modelmapper](http://modelmapper.org/).
+
+#### Validation
+
+Validate all the input according to the rules described in [DataSource](#datasource). It can be done by directly
+implementing all validations in business logic code or declaratively, e.g. via custom annotations.
+> To support your custom annotations and perform validation outside of business logic code you can use
+> e.g. [Aspects][1].
+
+#### Module Main
+
+- Use Command pattern to call operations
+- Instead of direct call module-web from module-main organize communication between module-web and module-main by custom
+  annotations @CommandHandler, @CommandBody and @CommandParam placed in controllers
+
+#### Testing
+
+- [x] Cover service layer with JUnit tests.
+
+#### General requirements:
+
+1. Code should be clean and should not contain any “developer-purpose” constructions.
+2. App should be designed and written with respect to OOD and SOLID principles.
+3. Clear layered structure should be used with responsibilities of each application layer defined.
+4. All business logic should be written in the module-service: mapping `model` to `dto` and vice versa, validation, etc.
+5. All the news and author data should be generated automatically in the module-repository with the amount of 20 and
+   stored in array (database emulation) when the application is running. Reading default data for news and author
+   generation should be from files in `resources` package, e.g. `author.txt`, `content.txt` and `news.txt`.
+6. Module-web and module-service should accept and return `dto` objects.
+7. Module-repository should accept and return `model` objects.
+8. Convenient error/exception should be implemented: all errors should be meaningful. Errors should
+   contain `errorMessage` and `errorCode`, where `errorCode` is your custom code.
+9. Application should be tested and pass all tests suites.
+
+#### Application requirements:
+
+1. Java 17 should be used.
+2. Gradle. Multi-module project. Spring.
+3. Application packages root: `com.mjc.school`.
+4. Java Code Convention is mandatory.
+
+[1]: https://docs.spring.io/spring-framework/docs/5.3.x/reference/html/core.html#aop