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Thor TWEeT #18: IntellisenseX for Nested Objects

IntellisenseX provides dropdown lists for nested objects. These dropdown list are available throughout an entire form or class, as shown in this example:

The key to making this work is to define a property that can used by IntellisenseX to determine the dropdown list. 

The name of the property is the name of the nested property (“oParts” in the example above) with “_Def” added as a suffix.

The value of the property is basically the same as used for Local Aliases (which apply only to the current procedure; see Using Local Aliases in IntellisenseX) or for Global Aliases (which apply everywhere; see the Alias Dictionary). It can be any one of a number of things, referring to either tables or objects.

  • A table, cursor, or view name
  • The full or relative path name to a table
  • The name of an SQL table
  • A reference to class from a class library; thus,  “{class, classlibrary}“  See note below for Forms and VCX classes.
  • A reference to class using the same syntax as the LOCAL command; thus,  “Local loPAL as PAL of BO_PAL.VCX“
  • A reference to an object; thus,  “Thisform.oParts “
  • An executable expression that returns an object or the name of an table, cursor, or view. This executable must start with an “=”; thus, something like “= MyGetObject(‘Parts’) “.  See note below for Forms and VCX classes.

An unexpected problem arises when when using the Property Sheet or PEM Editor to set the values for the two items noted above – values inside curly braces are converted to dates, and values beginning with an = sign are saved as expressions. To avoid these issues, prefix the values with && – thus:

  • “&& {class, classlibrary}“
  • “&& = MyGetObject(‘Parts’) “

This table shows a number of different values that can be used for the value of the “_Def” property:

Value Description
“PartsList” The name of a table in the path, in the Data Environment of a form, in an open DBC, in the MRU list for tables, or the name of a table in a SQL Server database. It can also be opened by the plug-in “Open Table”.
“..\Tables\PartsList” The absolute or relative path to a table.
“{NISDetailsForm, NIS.VCX}” A class in a VCX or PRG
“Local loPAL as PAL of BO_PAL.PRG” An alternative way to reference a class. This syntax was chosen so that you can copy the LOCAL command directly from a line of code.
“ = GetBusinessObject(‘TableName’)” A call to your own UDF that returns an object; used, for instance, if you use a factory to return objects instead of direct references.

Nested objects may take any of a number of forms, including:

  • ThisForm.oBusObj
  • This.oData
  • This.oPartsList.oData
  • This.oBusObj.oPartsList.oData

Nested objects may appear in forms, VCX-based classes, and PRG-based classes and there can be multiple levels of nesting.

This TWEeT has addressed Aliases that apply to an entire form or class (both VCX and PRG-based).  Earlier TWEeTs have addressed Local Aliases and the Alias Dictionary addressed global aliases.

An upcoming TWEeT will describe plug-ins that be used to handle cases that these features do not.

See also History of all Thor TWEeTs and the Thor Forum.