OpenCities Map CONNECT Edition Help

Expression Builder Dialog for Item Types

Used to create valid expression equations to calculate the value of a property definition. It allows you to define the syntax for an expression by using numbers, strings, access strings, symbols, and operators.

You can access this dialog from the following:
  • Drawing > Attach > Item Types dialog

Select the desired Property Definition and click in the Expression field under Calculated Properties. Select the options button.

The Expression Builder dialog opens.

You can type in the expression you wish to use and test it in the expression editor section of the dialog. Once you start typing, you will be prompted with possible options to complete the expression.

For example, you want to create an expression for "this" function group, when you type "this.", you will be prompted for properties and tools in a drop-down menu, that can be added to the syntax. You can double-click on the desired item from the drop-down to add it to the expression syntax.

Show Function Group

Expands to show the different function groups available. From the Select Function Group drop-down you can select the desired group. Based on your selection the list of functions and properties is populated. When you double-click on a function or property in the right-hand side pane, you will see the expression displayed on the right-hand side along with its description at the bottom in the dialog.


If selected, shows all Functions in the group.

If selected shows all Properties in the group.
Hide Function Group

Hides the function group pane.
Show Function group at current caret position

Opens a list of function groups. You can select a function group by double clicking on it.
Concat Adds the concatenation symbol to expression. This symbol is used to concatenate the result of two expressions. For example this.GetElement().ElementID & ActiveFile.FileName will give the combined result of both expressions.
Select Operator Provides the below options:
  • Arithmetic
  • Comparison
  • Conditional
  • Logical
Toolbar Based on the option selected in Select Operator, displays relevant arithmetic, comparison, conditional and logical operators.
  • Add (+)
  • Subtract (-)
  • Multiply (*)
  • Divide (/)
  • Exponent (^)
  • Modulo (%)
  • Equal to (==)
  • Not equal to (!=)
  • Less than (<)
  • Greater than (>)
  • Less than equal to (<=)
  • Greater than equal to (>=)
  • And (&&)
  • Or (| |)
  • Not (!) - Negates a True or False value
  • Condition IIf
Expression Editor Provides a text field where you build the expression.
Clear Provides a text field where you build the expression.
Test Checks the validity of the expression and gives comments for error/success in the field below.
OK Closes the dialog and adds the expression in the Expression field of the Item Types dialog.
Cancel Cancels and closes the dialog.