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I've only worked at once place since graduating my CS degree. This is a pretty basic architecture question but i don't know any better since i've only worked at one place. Where i work we maintain a large number of code tables. For example say you have a Sales/Order system and you have an Order Status. We would maintain an order status table that would look like the following:

OrderStatus:

OrderStatusId(PK TinyInt)  OrderStatusDesc(VarChar(50))  
1                         Created  
2                         Submitted 
3                         Processing
4                         Canceled
5                         Verified
6                         Complete

We then create an enumeration off each code table. For example:

Public Enum TblSalesOrderStatus
      eosCreated = 1
      eosSubmitted = 2
      eosProcess = 3
      eosCanceled = 4
      eosVerified = 5
      eosComplete = 6
End Enum

Then in our code we have code like the following:

If OrderStatus = eosCreated OrElse OrderStatus = eosSubmitted Then
    ...do some work
End if

On every screen we create we have the id's stored in the controls (like comboboxes). I don't know something about this has always made me think its bad design. Maybe i'm wrong though. Especially when i started getting into REST design. i wanted to pass the Ids rather than descriptions. Of course this doesn't seem right since i'd be the only one i've ever seen pass those type of Ids in a REST service. So is this bad design?

Edit:
Trying to make thing a little clearer. Are Code Tables are only stored in two places: The Enum + The Database. When we need a new Id when email our database staff which creates a new code table value for us and emails us back the Id. When then put the new value into our enumerations. We never had problems with it getting out of sync but if we have needed either delete values or change them in the past (adding is easy) which has been pain because everything in the system had to be recompiled.

We have went down the route of trying to make things semi-dynamic (which doesn't work out in every case but helps in some). There are tons of examples but a simple example is we have a IsVisible flag in some of the code tables. If we ever want to obsolete or make one of the values not selectable then we set the IsVisible flag = 0. They prefer this compared to having to change code/compile/deploy. Thinking about it i think it would be preferable to have it in buisness logic and have test around it (which we don't :-( ) depending on your prospective.

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when you say you want to pass the Ids rather than descriptions - pass from what to what? And I think id's stored in the controls means that when the user selects "eosCanceled" the combo box knows that maps to 4? And is that the combo box as it exists on the client or a server side control that gets "eosCanceled" as post data from a browser (which might explain my what gets passed to what question as well perhaps)? –  psr Jul 21 '12 at 2:00
    
I was talking about returning Code Table Ids in your REST Service rather than the description of the status so i would be returning <OrderStatus>1</OrderStatus> rather than <OrderStatus>Created</OrderStatus>. The controls don't store the enumeration description they store the Id + the Description. The user will only see "Created" but in the code we will know they selected "1". For example we inherit the combo box and have our on custom combobox so we can do "If Combobox.SelectedIndex = eosCreated Then". What i'm referring to is more client rather than browser apps. –  coding4fun Jul 21 '12 at 2:10
    
passing id's or strings is NOT about making your Service REST ? –  Yusubov Jul 21 '12 at 4:58
    
Storing the same data in 3 places (GUI, as Enums and in database) is not good. The data may get out of synch. Never sacrifice data integrity. –  Emmad Kareem Jul 21 '12 at 9:04
    
@Emmand. They are actually only stored in two places. The database + the enums. The Statuses aren't hard coded in the controls. They are retrieved from the database tables talk about above. We have to make a request to our database staff when we want a new code table value. Then will then email us a new Id which we put in our enum. –  coding4fun Jul 23 '12 at 1:21

1 Answer 1

I don't know if this is officially "good" or "bad", but I have worked for a company where we used (and they use currently) this approach, with some differences:

  • we had one code table, and each row was identified (and indexed on) the ["code type", "code id"] pair;
  • there was a "master type" that described the code types themselves, so it was easy to add a new code type: added one row to the "master" code type, and the rows of the actual codes;
  • we had other columns in this table, so we could add external information to the codes, which was used by the actual code type handler.

It was not only useful for storing string values for code ids. For some types (data tables, GUI panels, forms, letters, ...) we put the actual handler Java class name into the code store record, and when referred to "table 42", we got an actual business logic object filled with data. Yes, Spring was not there at that time.

I think this is basically a good design, let us create a very modular system and quick prototyping. The only problem with this approach was that a part of the "system" was actually the content of a data table, which was not easy to keep in sync with the codes and app versions (we put code table dumps into the version control system, not a nice thing).

Therefore today I would not store this table in a database, but in a plain text file (json, xml, cfg, whatever), which is easy to diff(!!!) and can be stored, branched, etc. in the version control, directly linked to the sources, because their combination forms the actual deployment version of the application.

So in your case, I would also add this "master code store" containing all the other code types (if not exist yet) to centralize the type management, and perhaps would collect the many small tables into a single table, with a type column. With indexed queries, (or even: views that would make this change transparent to the existing codes!) there is practically no performance difference, but it is much easier to maintain one code table. Using the master type, you can even write a nice manager tool (as we did, and it felt good: the management of some low priority codes was delegated to the client administrators).

Also, the combo boxes don't have to "know" the actual code table, only the type id in the common table. Practically, one combo class is enough, adding a new type means using the same combo box with the new id (the int/enum conversion does not belong to the GUI element, but the control logic listening to the combo).

I would even consider to programmatically generate the enum source codes from the table. This is a repetitive task, and I think it is quite easy to make mistakes here, but not that hard to automatize. It would somehow "protect" the content of the code table as well: "touch it only if you are ready to explain why other coders have to refactor their code to use the modified enums..." :-)

About passing the ids: you are absolutely right!

Your business logic has to know that you have the value enum blahBlah in field AAA - this has a meaning in your context (the fact that field AAA uses code type 42 is also out of scope for your business logic, that is an external configuration info). The combo box is responsible for knowing that id 2 in type 42 should be displayed as "Blah blah blah", and when the user selects the string "Yippiee hoo!" it is id 6 in type 42, and should NOT know that id 6 means enum yippieeHoo for your business logic! A totally different set of responsibilities - and I have not yet mentioned language versions, what makes this even more evident ;-)

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First of all Lorand I want to thank you for the time you took in coming up with an excellent answer to my question. I do want to try to make sure i understand it fully though. Oh ya and by the way the idea on having one master code table with a secondary type table was a great idea. Anyways in context to a REST Service. –  coding4fun Jul 23 '12 at 1:15
    
You would pass the string across the wire (for example <OrderStatus>Open</OrderStatus> and then when your clients makes a POST/PUT to your rest service then you would need to look up the Id for "Open" or whatever it been in the database so business logic can do the correct thing. Of course i don't ever want to see anything like this "If OrderStatus = Open Then" –  coding4fun Jul 23 '12 at 1:15
    
Of course this would i think mean to load your combo boxes (or whatever your controls you use on the screen) then you would have to make a call to the service to load them for example: myorderingservice/codetables/OrderStatuses –  coding4fun Jul 23 '12 at 1:17
    
I don't know your system or HTML/JavaScript, so I can only give you some general viewpoints to consider. The idea was not mine, but it can serve you well in this case: the generic service (codetables) is cool, where the OrderStatuses is a parameter, sent by the combo having OrderStatuses as a type parameter(!) (and think of a "language" param in the user session). The response is a [codeId, string] table: the string to be displayed in the combo, it is responsible for string-code mapping. I recommend using codeId only, through the wire to the business logic (<OrderStatus>1</OrderStatus>). –  Lorand Kedves Jul 23 '12 at 7:54
    
I definitely wouldn't pass the descriptions over the wire, as it makes i18n an order of magnitude harder. Plus, if you're storing IDs in the database, then you have to look up the ID for the description, which is useless overhead when you could simply pass the data you need right in the request. –  TMN Jul 23 '12 at 13:02

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