Use Expression Editor to Build Expressions for Properties

Building an expression

1. You can drag and drop methods or properties from the Object Browser into the Editor panel. In the example below, the Concat(System.String str0,System.String str1) method is being dragged into the Editor. Once dropped, its parameters appear as hyperlinked text, which you can replace with actual values.

   The following image shows how to drag and drop a method to the Editor:

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   The following image shows the method after it is dropped into the Editor:

   

2. After dropping the System.String.Concat method into the Editor, you need to replace its parameters. To do this, click on each parameter and type the desired text. Ensure that the text is enclosed in double quotes, as shown below.

   The following image shows how to replace method parameters by entering text:

   

3. Alternatively, you can replace the parameters by placing string objects on the parameters by dragging and dropping them on to the method parameters that are shown in hypertext format. You can also use existing variables or application content of the application by expanding the Workflow Instance node and dragging and dropping variables on to the parameters as shown in the image below. The result is shown in the image following the one below.

   The following image shows how to replace method parameters by dragging and dropping Workflow Instance object nodes:

   

   The following image shows how to replace method parameters by dragging and dropping:

   

4. After completing the expression, you must click the OK button to save it. The submitted expression will be compiled and saved using the C# code compiler. If there are any errors in the expression, a message box will appear displaying the issue.

   Note: Copy-paste of variable texts from notepad will not parse the actual variable value as the referenced functions are not available. Referenced functions are available only in case of drag and drop of variable node, available from the left tree.

Debugging the expression

If an expression contains errors, they will appear in the Error List, which you can use to debug the issue. First, click the OK button in the error message box to close it. Then, locate the Error List link at the bottom-left of the Expression Editor window. Hover your mouse over this link to open the Error List, as shown in the image below.

Expression added to the property

Once the expression is completed without errors, it is added to the text box of the corresponding property in the Action Properties section. In the example below, the expression built in the previous steps appears as the value for the Action Display Name property. To modify the expression, click the Expression Editor icon. A Clear Expression icon will also appear next to the expression; clicking it will remove the current expression so you can enter a different value.

The following image shows the saved expression displayed in the Activity Properties section: