Optional validation dependent upon parameters

Question

I have a 'Validator' class that needs to do some simple validation. However, there are some instances where all or just a single method may need to be called.

The interface for the validator is defined as:

  internal interface IBrandValidator
  {
    BrandInfo ValidateBrands();
  }

The class definition for the object being returned:

  internal class BrandInfo 
  {
    public Organisation Brand { get; set; }
    public Client Client { get; set; }
    public Location Location { get; set; }
    public Language Language { get; set; }
  }

The class that implements this interface:

internal class ClientValidator : IBrandValidator
  {
    private readonly int? clientId;
    private readonly int? locationId;
    private readonly int? languageId;

    public ClientValidator(int clientId, int? locationId, int? languageId)
    {
      this.clientId = clientId;
      this.locationId = locationId;
      this.languageId = languageId;
    }

    public BrandInfo ValidateBrandDimensions()
    {
      var brandInfo= new BrandInfo();

      //Optional validation
      if(client != null)
         brandDimensions.Client = ValidateClient(clientId);
      if(locationId != null)
          brandDimensions.Location = ValidateLocation(locationId);
      if(languageId != null)
          brandDimensions.Language = ValidateLanguage(languageId);

      return brandInfo;
    }
  }

My question is. The 3 validation methods under the comment 'Optional Validation'. May or may not need to be called. However, there may be additional things I need to validate in future and using the nullable int with the if statement is a bad route.

Is there a design pattern I can implement to achieve something similar?

May be do a separate implementation of your interface?

Giorgi Nakeuri
– Giorgi Nakeuri

2015-10-05 08:39:10 +00:00
Commented Oct 5, 2015 at 8:39 — Giorgi Nakeuri
– Giorgi Nakeuri, Commented Oct 5, 2015 at 8:39

Stephan Schinkel · Accepted Answer · 2015-10-05 08:50:16Z

1

Your code is hardly predictable by reading for example:

brandDimensions.Client = ValidateClient(clientId);

ValidateClient should return truthy or falsy object. But is assigned to an Object with name "Client". Your validator returns an BrandInfo Object. But does not include any property or method which indicates if it is valid or not ?!?

The ClientValidator does not have to validate for a client - because it is nullable?

It think you should consider to reorganize part of your codes.

If a class creates many objects from an Identifier you could probably use the Factory Pattern.

If you want to validate a complex object name it after ComplexObjectValidator. Every part of the complex object gets validated.

If it is valid that for example an Id is nullable put that check in the Validator Implementation.

It is hard to tell more specifics because it is unclear what your code does or intends to do.

Edit: As rule of thumb:

Truthy or falsy Methods: Prefix with "Is" "Must" "Should" "Has" "Can" etc. If a method should return an Object: "GetValidatedClient" "ValidateAndReturnClient" "CreateClient"

So someone reading your code which can be you in the future (6 months, 3 years, 10 years) can just infer the behaviour from your function names.

ValidateClient would imply that it is just Validating. More specifically it just returns void. Because it just Validates. If it returns truthy or falsy values use one of the prefixes listed above. If it returns an Validator Object use "GetValidationResultFor(xyz)" for example.

edited Oct 5, 2015 at 8:50

answered Oct 5, 2015 at 8:44

Stephan Schinkel

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1 Comment

JBond Over a year ago

Thanks for the response. Each validation method does return an object. If it fails validation, an exception is thrown. I will use the naming convention you've mentioned.

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