BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  OOP in database programming - Newbie question Goto page 1, 2, 3, 4, 5  Next          BorlandTalk.com Forum Index -> Delphi Non-Technical View previous topic :: View next topic   Author Message Gary Lowe Guest Posted: Fri Jul 22, 2005 1:43 am    Post subject: OOP in database programming - Newbie question Delphi 5 pro I have no formal Delphi training, but I have written several database programs for inventory control. Basically they track containers and what is in them and all data is accessed through database controls. My question is this: Is there any advantage to creating an object representing the container, contents and it's location, manipulating this data and then passing the data to a routine for inclusion into the database? It seems a little redundant to me, but I really don't know the power or possibilities of the use of OOP in this situation. Any help or comments are welcome. Just be patient and understand that I am not really a programmer in the true sense of the word. Thanks Back to top Lauchlan M Guest Posted: Fri Jul 22, 2005 2:45 am    Post subject: Re: OOP in database programming - Newbie question Quote: My question is this: Is there any advantage to creating an object representing the container, contents and it's location, manipulating this data and then passing the data to a routine for inclusion into the database? It seems a little redundant to me, but I really don't know the power or possibilities of the use of OOP in this situation. Any help or comments are welcome. Just be patient and understand that I am not really a programmer in the true sense of the word. Hi, what you would be discussing is object persistance frameworks (OPFs) or Model Driven Architectures (MDAs) I suggest if you use Win32 look at tiOPF and Instant Objects, if you use ..net there are a number of soutions (Developer Express have one) and if you have D2005 Architect, look at ECO. As to whether there are benefits for you, that is for you to decide. <g> I'd experiment using object persistence frameworks with a seperate small project and see how you feel then. See also the Borland delphi.oodesign and delphi.modeldrivearchitecture.general newsgroups . . . HTH Lauchlan M Back to top Joanna Carter (TeamB) Guest Posted: Fri Jul 22, 2005 8:31 am    Post subject: Re: OOP in database programming - Newbie question "Gary Lowe" <cincylap (AT) earthlink (DOT) net> a écrit dans le message de news: [email]42e04f32 (AT) newsgroups (DOT) borland.com[/email]... Quote: I have no formal Delphi training, but I have written several database programs for inventory control. Basically they track containers and what is in them and all data is accessed through database controls. Accessing data through data-aware controls is a very bad idea. You have tied your forms to one particular type of database and all the logic that reponds to data changes ends up being written on the forms and means that, should you change database provider, you then have to go through all your code and change it to accomodate the differences in database components. Quote: Is there any advantage to creating an object representing the container, contents and it's location, manipulating this data and then passing the data to a routine for inclusion into the database? It seems a little redundant to me, but I really don't know the power or possibilities of the use of OOP in this situation. The advantage of a true OOP approach is the separation of business logic from database code. Using an OPF means that you can change database details without changing any of your fundamental business logic. You should not need any business logic such as stored procedures, triggers, etc in the database as all that sort of logic never changes and is part of the the business layer. By using an OPF, you then have to find somewhere else, apart from the form to write your business logic; and this is where the business classes come in. Connecting the components on a form to the properties of a business object is a matter of either designing your own 'object-aware' controls (see my articles on MVP framework, linked to in the oodesign group), or you can use data-aware controls linked to a custom dataset class that knows how to talk to objects instead of database tables. Quote: Any help or comments are welcome. Just be patient and understand that I am not really a programmer in the true sense of the word. None of us were born programmers, most of us had to learn ) Joanna -- Joanna Carter (TeamB) Consultant Software Engineer TeamBUG support for UK-BUG TeamMM support for ModelMaker Back to top Dave White Guest Posted: Fri Jul 22, 2005 8:43 am    Post subject: Re: OOP in database programming - Newbie question "Lauchlan M" <LMackinnonAT_NoSpam_ozemailDOTcomDOTau> wrote Quote: what you would be discussing is object persistance frameworks (OPFs) or Model Driven Architectures (MDAs) As a self proclaimed newbie, an OPF may be a bit adventurous at your level. But I'd jump over to borland.public.delphi.oodesign and take a look at the thread " Organizing database access" from Bob Dawson that was posted in the past day or so - this will get you started without having to go down the fully OPF path. As Bob says, his current framewaork for object persistence extends to almost 200 units - you need to start small -- Dave White SpectraChrom Software www.spectrachrom.com .. Back to top David Clegg Guest Posted: Fri Jul 22, 2005 9:05 am    Post subject: Re: OOP in database programming - Newbie question I notice others have already chimed in here, but let me add that you really should pay close attention to whatever Joanna has to say on this subject, as she really knows her stuff here. She played a significant part in helping me to write my first OPF. I'd also echo the sentiment of Lauchlan and suggest checking out ECO. It's much more than an Object Persistence Framework, but does make it incredibly easy to separate your business objects from the persistence mechanism. It is however only available in Delphi Architect, and is a ..NET Framework only technology. If you are looking for a Win32 solution you could check out BOLD, which I guess you could say is ECOs daddy. Once again, this shipped with Delphi 7 Architect, and is available as a free download to D2005 users (not sure whether there is any SKU restriction there). I have also successfully used tiOPF in a Delphi 5 project. It is actively developed, has an active mailing list, and the author (Peter Hinrichsen) is incredibly helpful and receptive to e-mails. -- Cheers, David Clegg [email]dclegg (AT) gmail (DOT) com[/email] Vote 1 http://cc.borland.com/codecentral/ccweb.exe/listing?id=21489 Now supports Google Groups searching with Dyna-extend(tm) technology! QualityCentral. The best way to bug Borland about bugs. http://qc.borland.com "Here's to alcohol : The cause of, and answer to all of life's problems." - Homer Simpson Back to top K. Sallee Guest Posted: Fri Jul 22, 2005 9:26 am    Post subject: Re: OOP in database programming - Newbie question Quote: Is there any advantage to creating an object representing the container Depends on what you are doing. For a quick overview of each according to your needs, see "Summary: RAD vs. OPF" at http://www.techinsite.com.au/tiOPF/Doc/1_WhatIsAnOPF.htm Kevin -- Software for resource managers and researchers www.ecostats.com Back to top Edmund Guest Posted: Fri Jul 22, 2005 9:59 am    Post subject: Re: OOP in database programming - Newbie question Joanna Carter (TeamB) sighed and wrote:: Quote: I have no formal Delphi training, but I have written several database programs for inventory control. Basically they track containers and what is in them and all data is accessed through database controls. Accessing data through data-aware controls is a very bad idea. You have tied your forms to one particular type of database and all the logic that reponds I don't understand this part. I'm not too fluent in Delphi and database access in general. I'm trying to do a database app, but it has certainly been a very steep climb. Anyway, when you mean 'accessing data through data-aware controls is a very bad idea', isn't that how it has always been done? I take a datasource. a TTable. A DBGrid. Dump them on a form. Associate a TTable with the necessary Database, and table property. Then associate the datasource to the ttable and the dbgrid to the datasource and boom. Activate the ttable and Bob's your uncle. Now that's the wrong way of doing things? I think that's what I read in the manual (Delphi 4 Pro... so standards might have changed, and I'm still figuring out Delphi 7's database capabilities. Any clarifications appreciated. Edmund Back to top David Clegg Guest Posted: Fri Jul 22, 2005 10:21 am    Post subject: Re: OOP in database programming - Newbie question Edmund wrote: Quote: Anyway, when you mean 'accessing data through data-aware controls is a very bad idea', isn't that how it has always been done? I take a datasource. a TTable. A DBGrid. Dump them on a form. Associate a TTable with the necessary Database, and table property. Then associate the datasource to the ttable and the dbgrid to the datasource and boom. Activate the ttable and Bob's your uncle. The problem with this is you then have a 'live' link to the actual data in the database. When the values in the grid are changed, the data in the table is updated. So if there is any validation that needs to be done prior to posting, this can quickly degenerate into a mess of BeforePost, AfterInsert, OnValidate etc event handlers. And of course, all of this is embedded in the same class as your presentation logic (the form). IMHO, a much more maintainable approach is to seperate your business logic into a series of logical classes modelling the actual objects they represent (e.g. TCustomer, TInvoice, TWidget etc). This way the presentation logic and business logic can be cleanly seperated. Once this is done, the next step is to separate the business logic from the persistence logic, and this is the role that an Object Persistence Framework would normally play. So instead of calling Customer.Save, where the Customer class may require some knowledge of how to persist itself, you'd call DataBroker.Save(Customer). This last point is a bit contentious (as is the whole concept, when you get right down to it), and the way I've outlined is my preferred way of persisting objects. Prior to going the fully fledged OPF route, I went through an intermediary stage where I'd have the persistence logic in a TDataModule and expose methods such as DataModule.SaveCustomer(ACustomer: TCustomer) to handle the persistence. This may help to cushion the impact of moving to a more complex object oriented design, and yet still provide some benefits over a databound control based approach. For all the goss (and heated debates), you should check out the OO Design groups. But be sure to Google first, as this is a topic that is discussed often. -- Cheers, David Clegg [email]dclegg (AT) gmail (DOT) com[/email] Vote 1 http://cc.borland.com/codecentral/ccweb.exe/listing?id=21489 Now supports Google Groups searching with Dyna-extend(tm) technology! QualityCentral. The best way to bug Borland about bugs. http://qc.borland.com "Are you sure this is the Sci-Fi Convention? It's full of nerds!" - Homer Simpson Back to top Angra Mainyu Guest Posted: Fri Jul 22, 2005 10:44 am    Post subject: Re: OOP in database programming - Newbie question "David Clegg" wrote Quote: Edmund wrote: Anyway, when you mean 'accessing data through data-aware controls is a very bad idea', isn't that how it has always been done? I take a datasource. a TTable. A DBGrid. Dump them on a form. Associate a TTable with the necessary Database, and table property. Then associate the datasource to the ttable and the dbgrid to the datasource and boom. Activate the ttable and Bob's your uncle. The problem with this is you then have a 'live' link to the actual data in the database. When the values in the grid are changed, the data in the table is updated. So if there is any validation that needs to be done prior to posting, this can quickly degenerate into a mess of BeforePost, AfterInsert, OnValidate etc event handlers. And of course, all of this is embedded in the same class as your presentation logic (the form). Get outta here! Boy, ain't you never even heard of a "disconnected" ADO recordset being combined with the magic of a Delphi DataModule? ;) Some may consider it slightly quick and dirty and certainly it's nowhere near as elegant as OOP/OPF but OTOH it doesn't require science either... Back to top David Clegg Guest Posted: Fri Jul 22, 2005 10:53 am    Post subject: Re: OOP in database programming - Newbie question Angra Mainyu wrote: Quote: Get outta here! Boy, ain't you never even heard of a "disconnected" ADO recordset being combined with the magic of a Delphi DataModule? Heard of, but never used. :-) I prefer to deal in terms of classes which model my problem domain, which is why I initially liked an OPF approach, and have now migrated to a MDA one. However, your suggestion is definately a viable alternative, although one which I'll have to leave the specifics up to you to suggest :-) -- Cheers, David Clegg [email]dclegg (AT) gmail (DOT) com[/email] Vote 1 http://cc.borland.com/codecentral/ccweb.exe/listing?id=21489 Now supports Google Groups searching with Dyna-extend(tm) technology! QualityCentral. The best way to bug Borland about bugs. http://qc.borland.com "Here's to alcohol : The cause of, and answer to all of life's problems." - Homer Simpson Back to top Hannes Danzl[NDD] Guest Posted: Fri Jul 22, 2005 11:40 am    Post subject: Re: OOP in database programming - Newbie question Quote: Accessing data through data-aware controls is a very bad idea. You IMO you should add: except you can guarantee that your application is single user and never will be networked in any way. For single-user applications (iow exclusive access to the db) data-aware controls are a very nice and good thing imo. -- Hannes Danzl [NexusDB Developer] Newsgroup archive at http://www.tamaracka.com/search.htm Back to top Bob Dawson Guest Posted: Fri Jul 22, 2005 11:50 am    Post subject: Re: OOP in database programming - Newbie question "Edmund" wrote Quote: to the datasource and boom. Activate the ttable and Bob's your uncle. Now that's the wrong way of doing things? It's not a question of change (used to be right, now wrong) as a question of where you want to go. Using a TTable, for example--that's going to work fairly well for a single user desktop application with a few hundred rows of data, but it's simply not workable for a serious client-server system in which tables might contain millions of rows. That was as true when Delphi 4 came out as it is today. The same might be said of direct db access--handling validation and all other business logic in the UI and data handler events: it's going to be quick, convenient, and entirely workable for as long as the program being written remains simple enough for a single programmer to keep in his head. But once things get complicated, it's simply not possible to juggle in your head everything about (1) what you want to happen in the interface, (2) what you want to happen from a business/domain rules perspective, and (3) what activities need interaction with the datastore. OO techniques (and specifically layered architectures) are approaches to separating these concerns so you can deal with them one at a time. So to quote our friend MS, where do you want to go today? Straight-out-of-the-box RAD simply doesn't scale up. bobD Back to top Lauchlan M Guest Posted: Fri Jul 22, 2005 12:14 pm    Post subject: Re: OOP in database programming - Newbie question Quote: Accessing data through data-aware controls is a very bad idea. You IMO you should add: except you can guarantee that your application is single user and never will be networked in any way. For single-user applications (iow exclusive access to the db) data-aware controls are a very nice and good thing imo. Hannes, Doesn't Joanna's point << You have tied your forms to one particular type of database and all the logic that reponds to data changes ends up being written on the forms and means that, should you change database provider, you then have to go through all your code and change it to accomodate the differences in database components. Quote: still stand, in the single user case? Perhaps you need to qualify further, to suggest that data aware controls might be nice when 'you can guarantee that your application is single user and never will be networked in any way' _and_ you are happy to remain with one database vendor for the foreseeable future? Lauchlan M Back to top Lauchlan M Guest Posted: Fri Jul 22, 2005 12:25 pm    Post subject: Re: OOP in database programming - Newbie question Quote: I have no formal Delphi training, but I have written several database programs for inventory control. Basically they track containers and what is in them and all data is accessed through database controls. Accessing data through data-aware controls is a very bad idea. You have tied your forms to one particular type of database and all the logic that reponds I don't understand this part. Think the difference between a TEdit and a TDBEdit. In one you enter the data and there is no connection to the database other than a connection you make in the code, in the other the data is tied to a database record. With a TDBEdit, you might start handling events for BeforeEdit, AfterEdit, BeforePost, AfterPost, etc. The code is not all centralised in one place. If you make a clean conceptual and actual distinction between the 'presentation layer' and the 'business logic' you can use the presentation layer just for presenting (displaying), and centralise the business logic in a more ordered way. Many n-tier frameworks use this approach, for example see my article http://www.remobjects.com/articles/?id=46226804-2BBB-4D2E-92BA-C5A0204BE714 for an overview of one solution. The discussion in this thread is about focusing on the objects, and seperating out the layers of the objects, the data, the business logic, and the presentation, and Joanna's points were aimed at this. HTH Lauchlan M Back to top Angra Mainyu Guest Posted: Fri Jul 22, 2005 1:17 pm    Post subject: Re: OOP in database programming - Newbie question "David Clegg" wrote Quote: Angra Mainyu wrote: However, your suggestion is definately a viable alternative, although one which I'll have to leave the specifics up to you to suggest Another viable alternative is to use the Kim Madsen component set and that way he will get to hold users hand. ;-) Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> Delphi Non-Technical All times are GMT Goto page 1, 2, 3, 4, 5  Next Page 1 of 5   Jump to: Select a forum C++ Builder Newsgroups----------------C++ BuilderC++ Builder (ActiveX)C++ Builder (Announcements)C++ Builder (Command Line Tools)C++ Builder DatabasesC++ Builder Databases (ADO)C++ Builder Databases (Desktop)C++ Builder Databases (InterBase Express)C++ Builder Databases (Multi-Tier)C++ Builder Databases (SQL Servers)C++ Builder (Graphics)C++ Builder (IDE)C++ Builder (Internet)C++ Builder (Internet Socket)C++ Builder (Internet Web)C++ Builder (Jobs)C++ Builder (Language)C++ Builder (Language C++)C++ Builder (Compatibility with MFC)C++ Builder (Native API)C++ Builder (Non-Technical)C++ Builder (Students)C++ Builder (Third Party Tools)C++ Builder (Upgrade)C++ Builder (VCL)C++ Builder (VCL Components Usage)C++ Builder (VCL Components Development)C++ Builder (VCL Usage)C++ Builder (WinAPI)C++ Builder Installation Delphi Newsgroups----------------Delphi (General)Delphi ActiveX Controls UsageDelphi ActiveX Controls DevelopmentDelphi As400Delphi DatabasesDelphi Databases (ADO)Delphi Databases (dbExpress)Delphi Databases (Desktop)Delphi Databases (InterBase Express)Delphi Databases (Multi-Tier)Delphi Databases (SQL Servers)Delphi DeploymentDelphi GraphicsDelphi IDEDelphi InternationalizationDelphi InternetDelphi Internet Isapi-WebBrokerDelphi Internet WebSnapDelphi Internet WinsockDelphi JobsDelphi Language BASMDelphi Language ObjectPascalDelphi Model Driven Architecture (General)Delphi Model Driven Architecture (Third Party)Delphi MultimediaDelphi Native APIDelphi Non-TechnicalDelphi ObjectPascalDelphi OLE AutomationDelphi OO designDelphi OpenToolsAPIDelphi Reporting-ChartingDelphi RTLDelphi StudentsDelphi TeamSourceDelphi Thirdparty ToolsDelphi Thirdparty Tools (General)Delphi Thirdparty Tools (IntraWeb)Delphi Thirdparty Tools (RaveReports)Delphi UpgradeDelphi VCLDelphi VCL ComponentsDelphi VCL Components UsingDelphi VCL Components WritingDelphi WebServices SOAPDelphi WinAPIDelphi XMLDelphi Installationcomp.lang.pascal.delphi.components.misccomp.lang.pascal.delphi.components.usagecomp.lang.pascal.delphi.components.writingcomp.lang.pascal.delphi.databasescomp.lang.pascal.delphi.misccomp.sources.delphi JBuilder Newsgroups----------------JBuilderJBuilder AnnouncementsJBuilder Applet IssuesJBuilder As400JBuilder CompilerJBuilder CORBA/RMIJBuilder DatabasesJBuilder DB SwingJBuilder DebuggerJBuilder DeploymentJBuilder DocumentationJBuilder EnterpriseJBuilder HandheldJBuilder IDEJBuilder JavaJBuilder JavaAPIJBuilder Java LanguageJBuilder Java SwingJBuilder Java BeansJBuilder Java Beans UsageJBuilder Java Beans DevelopmentJBuilder JBCLJBuilder JDataStoreJBuilder JobsJBuilder LinuxJBuilder MacintoshJBuilder & MobileSetJBuilder MultiLingual AppsJBuilder Non-TechnicalJBuilder OpenToolsJBuilder Servlets (JSP)JBuilder StudentsJBuilder Team DevelopmentJBuilder Thirdparty ToolsJBuilder UpgradeJBuilder Installation InterBase Newsgroups----------------InterBaseInterBase Bug DiscussionInterBase GeneralInterBase IBConsoleInterBase OpenSourceInterBase ReplicationInterBase SQLInterBase ThirdpartyInterBase Installation Miscellaneous Borland Newsgroups----------------AppCenterAppServerEnteraVisiBroker  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.