Version: 18

Objects

Type

MANDATORY SETTING

This property designates the type of the active or inactive form object.

JSON Grammar

Name	Data Type	Possible Values
type	string	"button", "buttonGrid", "checkbox", "combo", "dropdown", "groupBox", "input", "line", "list", "listbox", "oval", "picture", "pictureButton", "picturePopup", "plugin", "progress", "radio", "rectangle", "ruler", "spinner", "splitter", "stepper", "subform", "tab", "text", "view", "webArea", "write"

Objects Supported

4D View Pro area - 4D Write Pro area - Button - Button Grid - Check Box - Combo Box - Drop-down List - Group Box - Hierarchical List - List Box - List Box Column - List Box Footer - List Box Header - Picture Button - Picture Pop-up Menu - Plug-in Area - Progress indicator - Radio Button -Spinner - Splitter - Static Picture - Stepper - Subform - Tab control - Text Area - Web Area

Object Name

Each active form object is associated with an object name. Each object name must be unique.

Object names are limited to a size of 255 bytes.

When using 4D’s language, you can refer to an active form object by its object name (for more information about this, refer to Object Properties in the 4D Language Reference manual).

For more information about naming rules for form objects, refer to Identifiers section.

JSON Grammar

Name	Data Type	Possible Values
name	string	Any allowed name which does not belong to an already existing object

Objects Supported

4D View Pro area - 4D Write Pro area - Button - Button Grid - Check Box - Combo Box - Drop-down List - Group Box - Hierarchical List - List Box - List Box Column - List Box Footer - List Box Header - Picture Button - Picture Pop-up Menu - Plug-in Area - Progress indicator - Spinner - Splitter - Static Picture - Stepper - Radio Button - Subform - Tab control - Text Area - Web Area

Variable or Expression

See also Expression for Selection and collection type list box columns.

This property specifies the source of the data. Each active form object is associated with an object name and a variable name. The variable name can be different from the object’s name. In the same form, you can use the same variable several times while each object name must be unique.

Variable name size is limited to 31 bytes. See Identifiers section for more information about naming rules.

The form object variables allow you to control and monitor the objects. For example, when a button is clicked, its variable is set to 1; at all other times, it is 0. The expression associated with a progress indicator lets you read and change the current setting.

Variables or expressions can be enterable or non-enterable and can receive data of the Text, Integer, Numeric, Date, Time, Picture, Boolean, or Object type.

Expressions

You can use an expression as data source for an object. Any valid 4D expression is allowed: simple expression, formula, 4D function, project method name or field using the standard [Table]Field syntax. The expression is evaluated when the form is executed and reevaluated for each form event. Note that expressions can be assignable or non-assignable.

If the value entered corresponds to both a variable name and a method name, 4D considers that you are indicating the method.

Dynamic variables

You can leave it up to 4D to create variables associated with your form objects (buttons, enterable variables, check boxes, etc.) dynamically and according to your needs. To do this, simply leave the "Variable or Expression" property (or dataSource JSON field) blank.

When a variable is not named, when the form is loaded, 4D creates a new variable for the object, with a calculated name that is unique in the space of the process variables of the interpreter (which means that this mechanism can be used even in compiled mode). This temporary variable will be destroyed when the form is closed. In order for this principle to work in compiled mode, it is imperative that dynamic variables are explicitly typed. There are two ways to do this:

You can set the type using the Expression type property.
You can use a specific initialization code when the form is loaded that uses, for example, the VARIABLE TO VARIABLE command:

 If(Form event=On Load)
    C_TEXT($init)
    $Ptr_object:=OBJECT Get pointer(Object named;"comments")
    $init:=""
    VARIABLE TO VARIABLE(Current process;$Ptr_object->;$init)
 End if

In the 4D code, dynamic variables can be accessed using a pointer obtained with the OBJECT Get pointer command. For example:

  // assign the time 12:00:00 to the variable for the "tstart" object
 $p :=OBJECT Get pointer(Object named;"tstart")
 $p->:=?12:00:00?

There are two advantages with this mechanism:

On the one hand, it allows the development of "subform" type components that can be used several times in the same host form. Let us take as an example the case of a datepicker subform that is inserted twice in a host form to set a start date and an end date. This subform will use objects for choosing the date of the month and the year. It will be necessary for these objects to work with different variables for the start date and the end date. Letting 4D create their variable with a unique name is a way of resolving this difficulty.
On the other hand, it can be used to limit memory usage. In fact, form objects only work with process or inter-process variables. However, in compiled mode, an instance of each process variable is created in all the processes, including the server processes. This instance takes up memory, even when the form is not used during the session. Therefore, letting 4D create variables dynamically when loading the forms can save memory.

Array List Box

For an array list box, the Variable or Expression property usually holds the name of the array variable defined for the list box, and for each column. However, you can use a string array (containing arrays names) as dataSource value for a list box column to define a hierarchical list box.

JSON Grammar

Name	Data Type	Possible Values
dataSource	string, or string array	4D variable, field name, or arbitrary complex language expression. Empty string for dynamic variables. String array (collection of array names) for a hierarchical listbox column]

Objects Supported

4D View Pro area - 4D Write Pro area - Button - Button Grid - Check Box - Combo Box - Drop-down List - Hierarchical List - List Box - List Box Column - List Box Header - List Box Footer - Picture Pop-up Menu - Plug-in Area - Progress indicator - Spinner - Splitter - Stepper - Tab control - Subform - Radio Button - Web Area

Expression Type

This property is called Data Type in the Property List for Selection and collection type list box columns.

Specify the data type for the expression or variable associated to the object. Note that main purpose of this setting is to configure options (such as display formats) available for the data type. It does not actually type the variable itself. In view of database compilation, you must use the 4D language commands of the Compiler theme.

However, this property has a typing function in the following specific cases:

Dynamic variables: you can use this property to declare the type of dynamic variables.
List Box Columns: this property is used to associate a display format with the column data. The formats provided will depend on the variable type (array type list box) or the data/field type (selection and collection type list boxes). The standard 4D formats that can be used are: Alpha, Numeric, Date, Time, Picture and Boolean. The Text type does not have specific display formats. Any existing custom formats are also available.
Picture variables: you can use this menu to declare the variables before loading the form in interpreted mode. Specific native mechanisms govern the display of picture variables in forms. These mechanisms require greater precision when configuring variables: from now on, they must have already been declared before loading the form — i.e., even before the On Load form event — unlike other types of variables. To do this, you need either for the statement C_PICTURE(varName) to have been executed before loading the form (typically, in the method calling the DIALOG command), or for the variable to have been typed at the form level using the expression type property. Otherwise, the picture variable will not be displayed correctly (only in interpreted mode).

JSON Grammar

Name	Data Type	Possible Values
dataSourceTypeHint	string	standard objects: "integer", "boolean", "number", "picture", "text", date", "time", "arrayText", "arrayDate", "arrayTime", "arrayNumber", "collection", "object", "undefined" list box columns: "boolean", "number", "picture", "text", date" (array/selection list box only) "integer", "time", "object"

Objects Supported

Check Box - Combo Box - Drop-down List - Input - List Box Column - List Box Footer - Plug-in Area - Progress indicator - Radio Button - Ruler - Spinner - Stepper - Subform - Tab Control

CSS Class

A list of space-separated words used as class selectors in css files.

JSON Grammar

Name	Data Type	Possible Values
class	string	One string with CSS name(s) separated by space characters

Objects Supported

4D View Pro area - 4D Write Pro area - Button - Button Grid - Check Box - Combo Box - Drop-down List - Group Box - Hierarchical List - List Box - Picture Button - Picture Pop-up Menu - Plug-in Area - Radio Button - Static Picture - Subform - Text Area - Web Area

Collection or entity selection

To use collection elements or entities to define the row contents of the list box.

Enter an expression that returns either a collection or an entity selection. Usually, you will enter the name of a variable, a collection element or a property that contain a collection or an entity selection.

The collection or the entity selection must be available to the form when it is loaded. Each element of the collection or each entity of the entity selection will be associated to a list box row and will be available as an object through the This command:

if you used a collection of objects, you can call This in the datasource expression to access each property value, for example This.\<propertyPath>.
if you used an entity selection, you can call This in the datasource expression to access each attribute value, for example This.\<attributePath>.

If you used a collection of scalar values (and not objects), 4D allows you to display each value by calling This.value in the datasource expression. However in this case you will not be able to modify values or to access the current ite object (see below) Note: For information about entity selections, please refer to the ORDA chapter.

JSON Grammar

Name	Data Type	Possible Values
dataSource	string	Expression that returns a collection or an entity selection.

Objects Supported

List Box

Data Source

Specify the type of list box.

Arrays(default): use array elements as the rows of the list box.
Current Selection: use expressions, fields or methods whose values will be evaluated for each record of the current selection of a table.
Named Selection: use expressions, fields or methods whose values will be evaluated for each record of a named selection.
Collection or Entity Selection: use collection elements or entities to define the row contents of the list box. Note that with this list box type, you need to define the Collection or Entity Selection property.

JSON Grammar

Name	Data Type	Possible Values
listboxType	string	"array", "currentSelection", "namedSelection", "collection"

Objects Supported

List Box

Plug-in Kind

Name of the plug-in external area associated to the object. Plug-in external area names are published in the manifest.json file of the plug-in.

JSON Grammar

Name	Data Type	Possible Values
pluginAreaKind	string	Name of the plug-in external area (starts with a % character)

Objects Supported

Plug-in Area

Radio Group

Enables radio buttons to be used in coordinated sets: only one button at a time can be selected in the set.

JSON Grammar

Name	Data Type	Possible Values
radioGroup	string	Radio group name

Objects Supported

Radio Button

Title

Allows inserting a label on an object. The font and the style of this label can be specified.

You can force a carriage return in the label by using the \ character (backslash).

To insert a \ in the label, enter "\\".

By default, the label is placed in the center of the object. When the object also contains an icon, you can modify the relative location of these two elements using the Title/Picture Position property.

For database translation purposes, you can enter an XLIFF reference in the title area of a button (see Appendix B: XLIFF architecture).

JSON Grammar

Name	Data Type	Possible Values
text	string	any text

Objects Supported

Button - Check Box - List Box Header - Radio Button - Text Area

Variable Calculation

This property sets the type of calculation to be done in a column footer area.

The calculation for footers can also be set using the LISTBOX SET FOOTER CALCULATION 4D command.

There are several types of calculations available. The following table shows which calculations can be used according to the type of data found in each column and indicates the type automatically affected by 4D to the footer variable (if it is not typed by the code):

Calculation	Num	Text	Date	Time	Bool	Pict	footer var type
Minimum	X		X	X	X		Same as column type
Maximum	X		X	X	X		Same as column type
Sum	X		X		X		Same as column type
Count	X	X	X	X	X	X	Longint
Average	X			X			Real
Standard deviation(*)	X			X			Real
Variance(*)	X			X			Real
Sum squares(*)	X			X			Real
Custom ("none")	X	X	X	X	X	X	Any

(*) Only for array type list boxes.

When an automatic calculation is set, it is applied to all the values found in the list box column. Note that the calculation does not take the shown/hidden state of list box rows into account. If you want to restrict a calculation to only visible rows, you must use a custom calculation.

When Custom ("none" in JSON) is set, no automatic calculations are performed by 4D and you must assign the value of the variable in this area by programming.

Automatic calculations are not supported with:

footers of columns based on formulas,

footers of Collection and Entity selection list boxes. You need to use custom calculations.

JSON Grammar

Name	Data Type	Possible Values
variableCalculation	string	"none", "minimum", "maximum", "sum", "count", "average", "standardDeviation", "variance", "sumSquare"

Objects Supported

List Box Footer

Type​

JSON Grammar​

Objects Supported​

Object Name​

JSON Grammar​

Objects Supported​

Variable or Expression​

Expressions​

Dynamic variables​

Array List Box​

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Objects Supported​

Expression Type​

JSON Grammar​

Objects Supported​

CSS Class​

JSON Grammar​

Objects Supported​

Collection or entity selection​

JSON Grammar​

Objects Supported​

Data Source​

JSON Grammar​

Objects Supported​

Plug-in Kind​

JSON Grammar​

Objects Supported​

Radio Group​

JSON Grammar​

Objects Supported​

Title​

JSON Grammar​

Objects Supported​

Variable Calculation​

JSON Grammar​

Objects Supported​

Type

JSON Grammar

Objects Supported

Object Name

JSON Grammar

Objects Supported

Variable or Expression

Expressions

Dynamic variables

Array List Box

JSON Grammar

Objects Supported

Expression Type

JSON Grammar

Objects Supported

CSS Class

JSON Grammar

Objects Supported

Collection or entity selection

JSON Grammar

Objects Supported

Data Source

JSON Grammar

Objects Supported

Plug-in Kind

JSON Grammar

Objects Supported

Radio Group

JSON Grammar

Objects Supported

Title

JSON Grammar

Objects Supported

Variable Calculation

JSON Grammar

Objects Supported