CODEWITHSUNDEEP
c#asp.net.netdto
user1112906
user1112906

Reputation: 61

CRUD operations on complex DTO

Need an advise on the "best" way to implement Update and Delete operations on complex nested DTOs. For very simple example, suppose we have this structure:

public class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public Employer Company { get; set; }
}
public class Employer
{
    public string Name { get; set; }
    public string Address1 { get; set; }
    public string City { get; set; }
    public string State { get; set; }
}

An update to Person as per Employer here can mean several things: 1. Previously there was no Employer for Person and we need to do insert to DB to introduce new Employer. 2. There was an Employer previously and we are just updating the Employer's inner Data 3. Employer has been removed from Person

Question:

If you have a domain/business compnent object something like PersonBusinessComponent with some method like PersonBusinessComponent.Update(Person) What is the best way to identify which scenario being executed and apply changes -- meaning if it is a delete operation then we'll call some EmployerDALC.Delete method or if it is an Insert then obviously EmployerDALC.Insert etc... I understand that one option is to get current version from Database and then tediously compare for existence of every nested object within Person, but I hope there is some better way or even probably more generic way that can be implemented to handle any such operations in the whole solution.

Note: I am not using MS Entity Framework.

Upvotes: 1

Views: 1548

Answers (1)

user1105802
user1105802

Reputation:

It depends on the architecture of your system. Is this a Procedural model, an ActiveRecord model or a Domain Model? I see you're using DTOs so that would imply a Domain model.

If so then your business logic (inside the 'Services' tier) would be responsible for orchestrating the operations, for example:

public interface PersonManager
{
  void CreateNewPerson(Person person);
  void DeletePerson(Person person);
  void ModifyPerson(Person person);
  // ... and so on .../
}

The PersonManager would then be responsible for examining the object and working out what to do with it based on the method run.

It would then defer down to its own business logic layer (which can converse with the DAL) to work out exactly how that should be achieved. For example with the Modify method it can query the DAL to get the current Employer's for that Person, defer to a ModifyEmployer if the employer has changed etc:

public void ModifyPerson(Person person)
{
  var currentEmployer = DAL.Employers.Get(Person.Employer.EmployerID);
  if (currentEmployer != person.Employer)
  {
    // Try and get a matching Employer from the appropriate Service (liaising with the DAL)
    var employer = EmployerManager.GetEmployer(person.Employer.EmployerID);
    if (employer == null)
    {
      // ... Create a new employer
    }
    else if (employer != person.Employer)
    {
      // ... Update existing employer
    }
  }

  // ... Now go ahead and handle any changes to the person
}

Off the top of my head I can't think of any particular package to handle this for you, generally I'd say it's all in the architecture of your system and how the BL talks to the DAL, but I'm sure one of the brain-boxes here will come up with some better suggestions :)

Hope that might help a little bit!

K.

Upvotes: 1

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