C# add validation on a setter method?

If you want to validate when the property is set, you need to use non-auto properties (i.e. , manually defined get and set methods).

If you want to validate when the property is set, you need to use non-auto properties (i.e. , manually defined get and set methods). But another way to validate is to have the validation logic separate from the domain object.

Class Customer { public string FirstName { get; set; } public string LastName { get; set; } public string Organization { get; set; } } interface IValidator { bool Validate(T t); } class CustomerValidator : IValidator { public bool Validate(Customer t) { // validation logic } } Then, you can say Customer customer = // populate customer var validator = new CustomerValidator(); if(!validator. Validate(customer)) { // head splode } This is the approach I prefer: A Customer should not responsible for validating its own data, that is another responsibility and therefore should live elsewhere. Different situations call for different validation logic for the same domain object.

I don't agree, even if your validation fails, your customer data is invalid. What's to stop it from writing garbage to the database if you mess up external validation? – Blindy May 25 at 15:58 @Blindy: Your persistence layer should be wired up with validators that don't persist if the validation fails.

– Jason May 25 at 15:59 @Blindy Customer shouldn't be responsible for writing to the database. That would be another responsibility that Customer shouldn't have. – Phil May 25 at 16:02 I understand the "Single Responsibility Principle" (SRP) but I always wonder where the 'cut-off' should be.

Meaning, you could take it too far...like creating a class to set properties (for you). I'm not saying anything about your example...I just seem to find myself asking 'How far should I go in applying SRP'? ...maybe I should ask this as a question?

– Prisoner ZERO May 26 at 12:34 @Prisoner ZERO: I think that's the good basis for another question, but you'll need to come up with a specific example to make it better defined. – StriplingWarrior May 26 at 14:55.

What you have now are called "auto-properties," and only perform a simple "get/set". In order to customize the behavior of the get or set, you will need to convert the properties to field-backed properties: private string _firstName; public string FirstName { get {return _firstName;} set { Validate(_firstName); _firstName = value; } } Note that I changed String to string and capitalized the property name, in following accepted C# naming best practices.

I wouldn't add validation in the setter at all. Rather, I would create a function called validate instead...that way all your validation code is in one spot rather scattered throughout your setters.

You have to use the full property syntax for this.

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