D365FO - Extension method data accessor examples

Six months into learning how to transition from AX 2012 X++ to D365FO X++ one of the things I have been struggling with the new extension model is how many different code structures you need in order to access the calling method’s property’s/datasource when subscribing to various types of events or methods. So I started to log down anytime I discover a new method. As I am sure there are plenty of other ones that I am missing as I have only touched the tip of the iceberg when it comes to field events but I decided it would be a good time to post this information as a reference. There is more than likely better ways to do some of these however I am posting this as a starting point.

I will be updating this post as my experience with D365FO grows as well

Source	Event	Parm	Example
Class	Pre/Post event	XppPrePostArgs	Get args and parmameter values from a method that is being extended. Parm 1 = Object Parm 2 = Common PurchCreateFromSalesOrder callingClass = args.getThis() as PurchCreateFromSalesOrder;        Object callerObject = args.getArgNum(1) as Object; Common callerRecord = args.getArgNum(2) as Common;
Class	Pre/Post event	XppPrePostArgs	Class example: SalesLineType salesLineType = args.getThis() as SalesLineType;
Class	main	args	Getting the caller record that is sent to a class via args. This is the same as 2012 however args.record().datasource() is now deprecated //check the caller if(_args.callerName() == formStr(SalesTable)) {         //check to see which dataset type was passed         if(_args.dataset() == tableNum(SalesLine))         {                 //get the forms datasource record (FormDataUtil::getFormDataSource() replaced _args.record().datasource())                FormDataSource salesLineDS = FormDataUtil::getFormDataSource(_args.record());         } }
Form	Initialized	xFormRun	FormDataSource purchLine = sender.dataSource(formDataSourceStr([formname],[table]));
Form	DataSource	FormDataSource	FormDataSource formDS = sender.formRun().dataSource(formDataSourceStr(EcoResProductDetailsExtended, MHSmartATPItemSettings)); MHSmartATPItemSettings smartATPItemSettings = formDS.cursor();
Form	DataSource Field	FormDataObject	FormDataSource formDS = sender.datasource(); PurchLine purchLine = formDS.cursor();
Form	Form Control	FormControl	FormRun formRun; FormControl formControl; formRun = sender.formRun(); formControl = FormRun.design().controlName(formControlStr(<form name>, <control name>)); someVariable = formControl.valueStr();
Form	onClicked	FormControl	FormRun formRun = sender.formRun();  FormDataSource formDSSalesTable = formRun.dataSource(formDataSourceStr(SalesTable, SalesTable));  FormDataSource formDSSalesLine = formRun.dataSource(formDataSourceStr(SalesTable, SalesLine));          SalesTable salesTable = formDSSalesTable.cursor();  SalesLine salesLine = formDSSalesLine.cursor();
Form	Pre/Post event	XppPrePostArgs	FormRun formRun = args.getThis(); FormDataSource formDSLogisticsPostalAddress = formRun.dataSource(formDataSourceStr(LogisticsPostalAddress, LogisticsPostalAddress)); LogisticsPostalAddress logisticsPostalAddress = formDSLogisticsPostalAddress.cursor();
Table	onDelete	Common	PurchLine purchLine = sender as PurchLine;
Table	Modified Field Value	Common	TableName itemSettings = sender as TableName; ModifyFieldValueEventArgs fieldEvent = e as ModifyFieldValueEventArgs;   //check to see which field was modified   switch(fieldEvent.parmFieldName())         {             case fieldStr([tablename], [fieldname]):             ...do stuff             break;         }
Table	ValidateFieldValue	Common/DataEventArgs	ValidateFieldValueEventArgs fieldEvent = e; boolean isValid; PurchLine purchLine = sender as PurchLine;         //declare the checkFailed       isValid = checkFailed("some error event"); //save the result fieldEvent.parmValidateResult(isValid);
Table	Pre/Post event	XppPrePostArgs	PurchLine purchLine = args.getThis() as PurchLine;
Form	Getting different datasource from calling object	FormDataObject	Get different datasource from formdataobject. Such as modified InventDim.InventLocationId -> PurchLine  FormDataSource formDS = sender.datasource(); InventDim inventDim = formDS.cursor(); FormRun formRun = sender.datasource().formRun(); FormDataSource formPurchLineDS = formRun.datasource(formDataSourceStr(PurchTable, PurchLine)); PurchLine purchLine = formPurchLineDS.cursor();

It is good to note that when it comes to accessing anything on a form I have realized the key component is getting access to the FormRun object. Once you have access to that then you can really access anything that is public on the form such as controls or datasources

Update 8/7/18: added class args example as args.record().datasource() is now deprecated
Update 1/23/19: added getting different datasource example than the sender's main common source