Vision - Dropdown List

The Dropdown component displays a list of choices in a limited amount of space. The list of choices is stored in a dataset, which can be manually typed in the Designer or populated dynamically from a property binding, often a SQL Query binding.

You may want to display choices to the user that are mapped to a different value internally, such as a numeric code. The columns in your dataset will determine which strings are visible to the end user (Selected Label) and which integers or strings are stored as the component's Selected Value or Selected String Value. There are three ways to configure a dropdown dataset:

Scenario 1: One column dataset with a set of string values

• Dropdown displays values from the first column
• Selected Value is undefined
• Selected String Value represents value from first column
• Selected Label represents value from first column

Scenario 2: Two column dataset with an integer and a string column

• Dropdown displays values from the second column
• Selected Value represents a value from the first column
• Selected String Value represents value from second column
• Selected Label represents value from second column

Scenario 3: Two column dataset with two string columns

• Dropdown displays values from the second column
• Selected Value is undefined
• Selected String Value represents value from first column
• Selected Label represents value from second column

The dropdown component can operate in one of three Selection Modes. These modes affect how the dropdown's current selection (defined by the values of its Selected Value, Selected String Value, and Selected Label properties) behave when the selection properties are set to values not present in the choice list, or conversely, when the choice list is set to a new dataset that doesn't contain the current selection:

• Strict. Selected values must always correlate to an option in the list defined by the Data property. If an invalid selection is set (via a binding or a script), the selection will be set to the value defined by the No Selection property. If the Data property is set to a list that does not contain the current selection, the current selection will be reset to the No Selection value.

• Lenient. (default) Selected values are independent of the list defined by the Data property. This mode is useful to avoid race conditions that can cause problems in Strict mode when both the Data and the Selected Value properties are bound. If the current selection is not present in the Data list, the read-only property Selected Index will be -1.

• Editable. The same selection rules as defined by Lenient mode, except that the dropdown itself becomes editable, allowing a user to type in their own value. This value will be set as the dropdown's Selected Label.

Properties

Scripting

Component Functions

This component does not have component functions associated with it.

Extension Functions

This component does not have extension functions associated with it.

Event Handlers

Event handlers allow you to run a script based off specific triggers. See the full list of available event handlers on the Component Events page.

Customizers

• Vision Component Customizers
• Style Customizer

Examples

#The following code will return the first column value of the selection.
#This code would be on a button in the same container as the dropdown.

selRow = event.source.parent.getComponent('Dropdown').selectedIndex
pyData = system.dataset.toPyDataSet(event.source.parent.getComponent('Dropdown').data)
code = pyData[selRow][0]
print code