Modelling a Chart of Accounts

[Stuart Ferguson]

A project I have recently started to work on involves me creating a Domain model that represents a Chart of Accounts within an Accounting package.

The information I need to hold on an account is as follows:

Id

Name

Description

Account Code

Parent Account Id

Account Type

Now my initial design was to have Account being the aggregate root but then I started to try and decide how the tree structure of the CoA would fit into that.  In reading a bit on this I have seen a number of different approaches on how this could be modelled, one of which was to hold the entire CoA under a single root and that each level had child accounts which fits with the Chart of Accounts structure exatly but now sure on how efficient that would be.

Does anyone have any thoughts/experiences on how I can achieve this.

The company I am working for is following a CQRS/Event Sourcing approach for this part of our system.

Any thoughts/help would be most appreciated.

Regards,

Stuart

[Greg Young]

I would guess CoA is a read model concept ...

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[Stuart Ferguson]

Hi Greg,

Thanks for the reply.

Yes I think you are right that is the case however, the challenge I have is that if a child account is created then some of the values allocated to it depend on the parent, which was why I struggled to see how this rule could be implemented.

The only suggestion I could see was at the Command Handling level rehydrating the new accounts parent and deriving the values from this rehydrated object.  

What I wasn't sure of with this approach is this was indeed a valid thing to be doing at the command handler?

This would mean each individual account would be stored as individual aggregate roots.

Regards,

Stuart

[Chris Sampson]

" the challenge I have is that if a child account is created then some of the values allocated to it depend on the parent," Wouldn't you model that relationship in an aggregate? Rather than rehydrating the accounts parent and deriving the values from the... etc 

[Chris Sampson]

Think about your events that you need first and then worry about composing them into aggregate roots that do what you want with those events in the most workable manner after, rather than coming up with the aggregate roots first.