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DataForm for Xamarin.Android: Group Layout

To separate the DataForm editors into groups, developers must use DataFormGroupLayoutManager.

// The context argument is the app context/activity.
dataForm.LayoutManager = new DataFormGroupLayoutManager (context);

Each editor will be put in the group specified in the @DataFormProperty annotation of the associated property.

For example if we have a Reservation class with a ReservationDate property:

public class Reservation 
    [DataFormProperty(Group = "Reservation Date")]
    public long ReservationDate 

We can annotate the getReservation() method with the @DataFormProperty annotation and specify the group for the editor. With this information, DataFormGroupLayoutManager creates an EditorGroup object for each group. EditorGroup represents a layout which contains a group header and a container for the editors for the group. Each EditorGroup can have a specific layout manager that will be used to arrange its editors. By default EditorGroup uses DataFormLinearLayoutManager.

Specifying a layout manager for each group

Developers can specify a custom layout manager with the setLayaoutManager() method just like setLayoutManager() on RadDataForm:

editorGroup.LayoutManager = new DataFormPlaceholderLayoutManager();

Creating special groups or modifying the default ones

To get a reference to the required EditorGroup object, developers can supply a callback that creates groups for every group name. For example:

groupLayoutManager.CreateGroup = new CreateGroupImpl();

public class CreateGroupImpl : Java.Lang.Object, IFunction2 {
    public Java.Lang.Object Apply(Java.Lang.Object context, 
        Java.Lang.Object groupName) {

        if(groupName.Equals("Reservation Date")) {
            EditorGroup group = new EditorGroup(
                (Context)context, groupName.ToString());
            group.LayoutManager = 
                new DataFormPlaceholderLayoutManager(
                    (Context)context, R.layout.placeholder_layout);
            return group;

        // Returning null will invoke the default group creation logic.
        return null;

If a property does not a have group set to it, it will be added to the default group which has a name of "", also known as the empty group.

When creating an EditorGroup developers can use another constructor that accepts a layout as its third argument. This allows custom group headers and custom positioning of the group header compared to the editors container. For example:

EditorGroup group = 
    new EditorGroup(context, groupName, Resource.Layout.custom_editor_group);

And the layout can look like this:

<LinearLayout xmlns:android=""

    <TextView android:visibility="gone"
        android:layout_height="wrap_content" />


Here the TextView with id data_form_group_header and the ViewGroup with id data_form_editor_group_container are mandatory.

Sorting the editor groups

The editor groups in DataFormGroupLayoutManager can be sorted by providing a simple callback by calling setSortGroups(). For example:

groupLayoutManager.SortGroups = new SortGroupsImpl();

public class SortGroupsImpl : Java.Lang.Object, IFunction, Java.Util.IComparator {
    public Java.Lang.Object Apply(Java.Lang.Object arg) {
        Java.Util.IList groups = (Java.Util.IList)arg;
        List<EditorGroup> groupsList = 
            new List<EditorGroup> (groups.ToEnumerable<EditorGroup> ());
        Java.Util.Collections.Sort (groupsList, this);

        return Java.Util.ArrayList.FromArray (groupsList.ToArray ());

    public int Compare(Java.Lang.Object lhs, Java.Lang.Object rhs) {
        EditorGroup left = (EditorGroup)lhs;
        EditorGroup right = (EditorGroup)rhs;
        return right.Name ().CompareTo (left.Name());

Using ExpandableEditorGroup

Finally, developers can make use of another group which is called ExpandableEditorGroup. The ExpandableEditorGroup class has one property - IsExpanded. ExpandableEditorGroup can also be created with a flag that indicates that it can be expanded only once. After it is expanded, the collapse button disappears.

// The third argument indicates whether the group can be expanded only once.
ExpandableEditorGroup expandableGroup = 
    new ExpandableEditorGroup (Context, "Reservation Date", true);
expandableGroup.IsExpanded = false;
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