README.md

Json auto validation

Json-auto-validation is a library for automatic validation of incoming json data in a spring-boot API.

Documentation

A full documentation is available here : Documentation

Description

Based on the automatic generation of json schemas and validation beans using annotations, its aim is to validate json data before deserialization, thereby minimizing deserialization errors and lightening the workload involved in verifying data after deserialization.

Installation

<dependency>
    <groupId>io.github.ugoevola</groupId>
    <artifactId>json-auto-validation</artifactId>
    <version>0.2.6</version>
</dependency>

implementation("io.github.ugoevola:json-auto-validation:0.2.6")

Example

Let's take an example. Consider an end point on our API as it is:

@RestController
@RequestMapping("cars")
class CarController(
  private val carService: CarService
) {

  @GetMapping
  fun getCarByFilter(
    @Validate filterDto: FilterDto
  ) = carService.getCarsByFilter(filterDto)

  @GetMapping("/{id}")
fun getCarById(
    @Validate @IsUuid @PathVariable id: String
) = cartService.getCarById(id)

}

The FilterDto class:

@JsonValidation
class FilterDto(
  @field:Required
  @field:IsEnum
  val brand: BrandEnum,
  
  @field:Required
  @field:IsInteger(minimum = 3, maximum=5)
  val nbDoors: Int,
  
  @field:IsBool
  val gps: Boolean?,
    
  val groupId: String  
)

The BrandEnum class:

enum class BrandEnum {
    Audi,
    Ford,
    Mercedes,
    Volkswagen
}

Therefore, tells json-auto-validation to intercept and verify requests before they are processed by the controller handler.

non-exhaustive list of requests that will be in error:

• GET /api/v1/cars?brand=Ford
• GET /api/v1/cars?brand=Audi&nbDoors=one
• GET /api/v1/cars?brand=Audi&nbDoors=42
• GET /api/v1/cars?brand=Peugeot&nbDoors=5
• GET /api/v1/car/84
• GET /api/v1/car/7856486875

non-exhaustive list of requests that will succeed:

• GET /api/v1/cars?brand=Ford&nbDoors=5
• GET /api/v1/car/4d9199af-decf-42d4-8f14-d9e6fc94729c

You can also create a custom Validator that perform more validation treatments before deserialization:

@Component
class FilterDtoValidator(
    private val groupController: GroupController
): JsonSchemaValidator<FilterDto>() {

    override fun validate(json: String) {   
        try {
            super.validate(json)
            val jsonObject = JSONObject(json)
            groupController.getGroupById(jsonObject.get("groupId"))
        } catch (exception: GroupNotFoundException) {
            TODO(deals with GroupNotFoundException)
        } catch (exception: ValidationException) {
            TODO(deals with ValidationException)
        }
    }
}