Drop Down

Last update: Edit

1 Introduction

A drop down is used to display and, optionally, allow the end-user to edit the value of an attribute of data type enumeration.

A drop down must be placed in a data widget and displays an attribute of the object(s) retrieved by that widget. The name of the attribute to be displayed is shown inside the drop down, between square brackets, and colored blue.

For example, the following drop down allows the end-user to see, and set, the Region to which a customer is allocated. The possible values for Region are held in an enumeration.

2 Properties

An example of drop down properties is represented in the image below:

Drop down properties consist of the following sections:

2.1 Common Section

For more information on properties in this section, see the Common Section section in Properties Common for Widgets.

2.2 Data Source Section

Attribute (Path)

Many input widgets (like text boxes and drop-down widgets) can be connected to the following:

  • An attribute of the entity of the data view that contains the widget; in this case, the widget is connected to an attribute
  • An attribute of an entity associated with the data view entity by following one or more associations of the reference type through the domain model; in this case, the widget is connected to an attribute path

In the first case, we say the widget is connected to an attribute, and in the second case it is connected to an attribute path.

In Mendix 8.0, an input widget connected to an attribute path must be read-only. Studio Pro will check this for you.

In Mendix 8.1 and above, you can edit attributes presented in input widgets over a path.

2.3 Design Properties Section

The Design Properties allow you to change spacing and alignment of the widget and hide it on phone, tablet, or desktop, if needed.

2.4 Editability Section

Editability determines whether an end-user can change the value in an input widget.

For more information on properties of this section, see the Editability Section section of Properties Common for Widgets.

2.5 Events Section

2.5.1 On Change

The on-change property specifies an action that will be executed when leaving the widget, either by using the Tab key or by clicking another widget, after the value has been changed.

For more information on properties of this section, see the Event Actions section of On Click Event & Events Section.

2.5.2 On Enter

The on-enter property specifies an action that will be executed when the widget is entered, either by using the Tab key or by clicking it with the mouse.

For more information on properties of this section, see the Event Actions section of On Click Event & Events Section.

2.5.3 On Leave

The on-leave property specifies an action that will be executed when leaving the widget, either by using the Tab key or by clicking another widget.

This differs from the On change property in that the event will always be triggered, even if the value has not been changed.

For more information on properties of this section, see the Event Actions section of On Click Event & Events Section.

2.6 General Section

2.6.1 Empty Option Caption

Empty option caption is the text that is shown for the empty option in the drop-down shown to the end-user. This is a translatable text. For more details, see Translatable Texts.

Adding a caption for the empty option improves the user experience of your application. It also helps end-users using a screen-reader to operate the application easily.

For example, the drop-down that allows the end-user to select the region allocated to a customer, where the possible values for Region are held in an enumeration, could have the caption Select a region.

2.7 Label Section

A label describes the purpose of a widget to the end-user.

For more information on properties of this section, see the Label Section section in Properties Common for Widgets.

2.8 Validation Section

Validation Type

This property indicates whether this widget value should be validated and, if so, how. These are the possible options:

  • No validation
  • A predefined validation
  • A custom validation

The possible values of a predefined validation are the following:

  • Required – all data types
  • E-mail – string
  • Positive number – decimal, float, integer, long
  • Date in the future – dateTime
  • Date in the past – dateTime

Custom validations are expressions that follow the Microflow expression syntax. Both $currentObject and $value are in a scope that refers to the current object and the current member value, respectively. In Mendix 8.1 and above, the expression can access objects of all the data containers enclosing that data container widget. These objects are available under the name of the widget they originate from (for example, $dataView1).

When a validation is set and it fails for this widget, a message will be shown when the user selects Save.

Default value: (none)

Validation Message

This property determines the message that is shown to the user if widget validation is enabled and has failed. This is a translatable text (for more information, see Translatable Texts).

For example, if an address field is required, the validation message for the text box of the address could be something like, "The address is required."

2.9 Visibility Section

Visibility determines whether a widget is displayed to the end-user as part of the page.

For more information on properties of this section, see the Visibility Section section in Properties Common for Widgets.

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