We centralise all data responding to new field values into the TDatasource.OnDataChange event. If Field is nil then some major change just happened (eg a new record being selected). If Field is assigned then that is the field which just changed so you can check if Field is one of the fields which should modify the price and if so call your routine for recalculating the price.
If you also need to initialise your price for each record while opening the dataset then you will need logic somewhere else as well (since OnDataChange is only called for the selected record in certain situations or when a field value changes) but hopefully you are storing the price in a field anyway so that isn't an issue. David. From: delphi-boun...@delphi.org.nz [mailto:delphi-boun...@delphi.org.nz] On Behalf Of Charlie Sent: Sunday, 18 October 2009 10:27 a.m. To: delphi@delphi.org.nz Subject: [DUG] Which event to use I'm using BDS 2006, InfoPower dbGrid and InfoPower dbComboLookups. My application is for orders that are placed to purchase the manufactured drawer boxes and uses master-detail tables; namely orders and orderdetail. Some of the detail data is entered in either dbEdits or dbLookups. These are used for data that is the same for each detail record. The dbGrid is used for the particulars for the items to be manufactured; namely, quantity, width, depth, height, and up to 7 options, the square foot price for the drawer box and the extended price (computed as square foot price * quantity + cost of the options selected). To determine the square foot price the program has to use the type of wood chosen for the drawer boxes, the height of the box, the price table and determine if the square feet for the box is greater than the minimum 1.5 square feet. Sometimes the program finds the correct price and sometimes it doesn't on the same order. I have a procedure that 'calculates' the price. I think that perhaps I'm over calling this procedure. The fields for the order and orderdetail tables are persistent. Currently there are several infopower lookup controls which have an OnCloseUp event. Some of these are attached to the infopower grid. The 'calculate' procedure is called in this event. The persistent fields call the 'calculate' procedure in the OnValidate and/or the OnExit event. And to top this off I have the dbGrid calling the 'calculate' procedure for the OnCellChange event. I guess I wanted to get the price figured out no matter what happened, lol. So the question is: What is the way I'm supposed to get the price figured out? Namely, do I use the DataSet's OnDataChange event, do I use the persistent fields' OnValidate event or is it better to use the OnChange event, do I use the dbGrid's OnCellChange event, or do I use the controls OnExit or OnCloseUp event. Or should I do something different? I've learned that most folks recommend against using a dbGrid the way that I am; but my bottom line is I need for each record to have the correct square foot price and the corresponding total for that record. Thank you for any help. Charlie
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