Coding Guidelines

Package structure

This package structure is based on multiple sources of best practices in Spring Boot, using roughly the “Package by layer” approach.

root
- config
- controller
- dapr
- dto
- exception
- persistence
  - dao
  - mapper
  - repository
- service
- validation

The detailed package structure is documented here.

Style Guide

Java

We use the default Oracle Styleguide, i.e., the default settings of IntelliJ, as a base. Also remember the Java naming conventions.

Special Style Rules

If acronyms are used in class, variable, or other names, only the first letter of the acronym should be capitalized, all other letters must not be capitalized, e.g. AbstractJsonToXmlConverter

GraphQL

Please regard the GraphQL naming conventions

How To…

How to validate input?

Field level validation

To validate the input the microservice receives on the field level, we can use a set of predefined graphQL directives. Example:

input CreateCourseInput {
    # Title of the course, max 255 characters
    title: String! @NotBlank @Size(max: 255)
    # Description of the course, max 3000 characters
    description: String! @Size(max: 3000)
   ...
}

This will automatically raise a graphQL error if for example the title in this example is blank. More information on these directives here

Class level validation

To validate an input class on class level, e.g., to check if a start date is before an end date or there are no duplicate items in the db, write your custom validation code in the validation package and call it in the corresponding service class.

Naming of services

Services follow the naming schema: “servicename_service”.