With this model I do not benefit much in distributed environment. There must be some property in Business Object and Logic to tackle situation like updating data which was already been deleted or already been update by another user. It is serious business functionality issue. Batch update options? Hi John, Sounds good. Good luck, and have fun with it!! Imar, Thank you so much for taking the time to write these articles.
I've manage to incorporate your design and methodology into my latest project. In fact, I've merged the File Upload and n-tier guidance into an app for managing images.
One question I have is, how would you handle uploading images to an album, if, in the context of the n-tier articles, an album was equivalent to a contact person, and an image was equivalent to an address, email address, or phone number? My API structure is exactly as you describe in the n-tier design, except for my object names and types, so within that context, how would you do this? Thanks in advance! Hi Chris, I am not sure I understand what you're asking. If you know how to upload and save files from the other article, and know how to set up the architecture from this series, what is it that you want to know?
Can you be more specific? Hi Imar Excellent Article! Few questions: 1. For BO, Can we use struct instead of class? Is it okay to have so many static methods in the project? Looking at performance perspective what improvements you suggest?
Thanks again for a series of very good articles. Regards Shailendra. Hi Johirul, 1 I wouldn't do it. Static methods only created once. Hi Imar, I greatly enjoyed this tutorial and decided to try to implement it. I chose one of the simple accessory tables id, name , created the appropriate classes business object, business logic, and data access and associated these with the ObjectDataSource of this particular table's GridView I even modified as you instructed in one of your replies above to allow sorting.
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The GridView displayed the table content nicely. I suspect that your implementation does not support it because I got an error message when the ObjectDataSource's Updating event fired. The error message is "The OrderedDictionary is readonly and cannot be modified" and is triggered by the following code: e.
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Am I wrong here? Thanks, Benny. Hi Benny, You bet it supports updating with the GridView. It would be a pretty useless solution if it didn't However, what may not be so obvious as I didn't show it in the article is that when you are calling methods that expect a Business Object like an Address or an EmailAddress as opposed to methods that accept individual parameters for the fields like Street, HouseNumber and so on , the InputParameters collection contains only one property: the business object itself.
So, you won't find a Street or a HouseNumber parameter but only a single parameter that holds the entire object. Simply cast it to the expected type, set its fields and let. NET handle the rest for you. InputParameters; myAddress.
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This is one of the best articles on layered applications I have read and I've read lots of them. Despite your cautionary note about using FormViews I am attempting to use one and have one minor problem. In the FormView I have a drop-down listing states. The states populate but I cannot get the selected value to work reliably. The first time I make a selection in the parent GridView, the selected value works and the correct state is indicated. NET best practices. I have recently started asp. Most of the articles i've read dont' really make much sense and dont' explain the concepts properly.
I love this article and really enjoyed reading it. It is very easy to understand and really makes sense. Only one area i feel you haven't covered and I think someone else has mentioned this too is optimistic concurrency. You know stuff like checking that the record you're updating hasn't already been updated by someone else or deleted by someone else.
Please can you expand on this. Hi David, I am glad you like the articles! I am sorry but I can't help much with the problem, without seeing your code. Hi Noreen, Yeah, that would certainly be a useful addition to the discussion. Unfortunately, I don't have the time to dig into this deep enough at the moment.
Here's short version of what you can. Either keep old state in the object for all previous versions and then do an update with a WHERE clause that uses all previous values. This is how controls like the SqlDataSource do it. Alternatively, give each row a timestamp or another unique row ID, like a Guid. In both cases, when 0 records have been affected you can see the update failed and act appropriately; for example, by passing false or an Enum type from the DAL all the way up to the UI where you can present a suitable error message. A lot has been written about this topic, so a Google search should give you a lot of useful results.
I posted a code snippet above with some tags removed so your system would allow it. This is a problem that is specific to the kinds of objects your are using in your article. I will definitely post on WROX as you suggest but was hoping for some guidance from the "master.
http://waahhh.com.my/amores-prohibidos-diario-de-un-hombre.php Hi David, Well, the "master" is a little busy at the moment, so he doesn't have the time to look at this so hopefully others on a forum can give it a try as well. Also, as you found out, it's difficult to post code here. I doubt it's a problem with the type of objects I create; all they do is get data from a database and fill BOs. However, I could be wrong of course I think this is one of the best articals has been written about the subject for beginners in n-tier. Most of the articals are lost in advanced topics.
I don't understand some people post here, why try to proof author is wrong. I beleive it is very nice, and clear start up project for somelike me who is switching to n-tier. Can you help me, please? Probably not much. You seem to know what to do create an overload of GetList and return a generics list of CPs. The concepts of GetItem a database parameter and GetList can easily be combined to build you what you need. Hi, Does anybody know when you use businessdatasource, how to catch error messages coming from business layer?
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I would like to show them in formatted label! Exception Cheers, Imar. Hi I've started doing my project in the object format you describe in the articles but am using vb.. On updating i'm fine but when i try to delete or create a new contact it's not working.. Hi Imar, I have a problem with inserting. Using GridView I use the footer row for entering new values.
The table is simple id - identity, and name and I need only enter name. My objectManager layer has Add method that accepts object custom as its sole argument like you explained. The ods of course has its TypeName attribute properly set to "objectManager" and the insertMethod is "Add". When I handle the Insert button click I call ods. Check that the 'values' dictionary contains values. Any ideas?