DDD - Validation of unique constraint

Posted by W3Max on Stack Overflow See other posts from Stack Overflow or by W3Max
Published on 2010-04-18T02:03:14Z Indexed on 2010/04/18 2:13 UTC
Read the original article Hit count: 430

Filed under:

ddd

|

validation

In DDD you should never let your entities enter an invalid state. That being said, how do you handle the validation of a unique constraint?

The creation of an entity is not a real problem. But let say you have an entity that must have a unique name and there is a thousand instances of this entity type - they are not in memory but stored in a database. Now let say you want to rename an instance.

You can't just use a setter... the object could enter an invalid state - you have to validate against the database.

How do you handle this scenario in a web environment?

© Stack Overflow or respective owner

Related posts about ddd

Implement DDD and drawing the line between the an Entity and value object

as seen on Stack Overflow - Search for 'Stack Overflow'
I am implementing an EMR project. I would like to apply a DDD based approach to the problem. I have identified the "Patient" as being the core object of the system. I understand Patient would be an entity object as well as an aggregrate. I have also identified that every patient must have a… >>> More
DDD with Grails

as seen on Stack Overflow - Search for 'Stack Overflow'
I cannot find any info about doing Domain Driven Design (DDD) with Grails. I'm looking for any best practices, experience notes or even open source projects that are good examples of DDD with Grails. >>> More
in DDD (gdb) how to skip passed loops

as seen on Stack Overflow - Search for 'Stack Overflow'
During many, sometimes inundating, debugging sessions using DDD, I stumble upon loops. And I keep pressing next to get passed it, and if there are many iterations, I just set a break point right after it, and press "continue." Is there any other way to go passed loops? Thanks >>> More
in DDD (gdb) how to skip past loops

as seen on Stack Overflow - Search for 'Stack Overflow'
During many, sometimes inundating, debugging sessions using DDD, I stumble upon loops. And I keep pressing next to get past it, and if there are many iterations, I just set a break point right after it, and press "continue." Is there any other way to go past loops? Thanks >>> More
Service Oriented Architecture & Domain-Driven Design

as seen on Stack Overflow - Search for 'Stack Overflow'
I've always developed code in a SOA type of way. This year I've been trying to do more DDD but I keep getting the feeling that I'm not getting it. At work our systems are load balanced and designed not to have state. The architecture is: Website ===Physical Layer== Main Service ==Physical Layer== Server… >>> More

Related posts about validation

How can I use Windows Workflow for validation of a Silverlight application?

as seen on Programmers - Search for 'Programmers'
I want to use Windows Workflow to provide a validation service. The validation that will be provided may have multiple tiers with chaining and redirecting to other stages of validation. The application that will generate the data for validation is a Silverlight app. I imagine the validation will… >>> More
HTML5 Form Validation

as seen on Stephen Walter - Search for 'Stephen Walter'
The latest versions of Google Chrome (16+), Mozilla Firefox (8+), and Internet Explorer (10+) all support HTML5 client-side validation. It is time to take HTML5 validation seriously. The purpose of the blog post is to describe how you can take advantage of HTML5 client-side validation regardless of… >>> More
HTML5 Form Validation

as seen on Stephen Walter - Search for 'Stephen Walter'
The latest versions of Google Chrome (16+), Mozilla Firefox (8+), and Internet Explorer (10+) all support HTML5 client-side validation. It is time to take HTML5 validation seriously. The purpose of the blog post is to describe how you can take advantage of HTML5 client-side validation regardless of… >>> More
Introducing Data Annotations Extensions

as seen on ASP.net Weblogs - Search for 'ASP.net Weblogs'
Validation of user input is integral to building a modern web application, and ASP.NET MVC offers us a way to enforce business rules on both the client and server using Model Validation. The recent release of ASP.NET MVC 3 has improved these offerings on the client side by introducing an unobtrusive… >>> More
jQuery validation per multiple fieldsets, how to use different event to trigger validation per secti

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi All! I have a really, really long form (about 300 fields) that I broke down into different sections using this slick jQuery plugin Form Wizard. If you group your form into different fieldsets, the FormWizard will automagically display one section at a time, with a Next hyperlink to take you to… >>> More