[FIXED] Spring\Spring Boot: Is there a need for a custom validator?

Issue

Suppose I have this controller mapping function:

@GetMapping("/result")
public Stats result(@RequestParam Integer homeId, @RequestParam Integer awayId)
        throws MissingTeamException, InvalidTeamIdExcpetion {

    //Validation starts here
    int numOfAvailableTeams = teamResource.retrieveAllTeams().size();
    
    if( homeId < 0 || homeId >= numOfAvailableTeams)
            throw new InvalidTeamIdExcpetion(homeId);

    if(awayId < 0 || awayId >= numOfAvailableTeams)
            throw new InvalidTeamIdExcpetion(awayId);
    //end of validation

    return generateResult(homeId, awayId);
}

You can see that I am validating the home and away ids.

Can I do a it in a cleaner way apart of creating a custom validator class?

Solution

Generally in every case logic should be wrote in service class (marked by @Service), not in controller. So, you can create a service class with method validating() with arguments needed to validate. Service example:

@Service
public class YourService {

    //This variable and constructor are optional because I didn't see your whole code.
    //But if you will to create TeamResource field in service, Spring Boot will automatically
    //inject teamResource if you have suitable Bean.
    private TeamResource teamResource;

    public YourService(TeamResource teamResource) {
        this.teamResource = teamResource;
    }

    public TypeOfMethodGenerateResult validate(Integer homeId, Integer awayId) {

        int numOfAvailableTeams = teamResource.retrieveAllTeams().size();

        if (homeId < 0 || homeId >= numOfAvailableTeams)
            throw new InvalidTeamIdExcpetion(homeId);

        if(awayId < 0 || awayId >= numOfAvailableTeams)
            throw new InvalidTeamIdExcpetion(awayId);

        return generateResult(homeId, awayId);
    }
}

And controller:

//Autoinject like in service.
private YourService yourService;

public YourService(YourService yourService) {
    this.yourService = yourService;
}

@GetMapping("/result")
public Stats result(@RequestParam Integer homeId, @RequestParam Integer awayId)
        throws MissingTeamException, InvalidTeamIdExcpetion {

    return yourService.validate(homeId, awayId);
}

Answered By - fr3ddie