Tree table

A tree table is a widget that allows you to display a tree of structs to users as a table and have them edit it (core.TreeTable). It combines a table and a tree: the fields are the columns and the items are the rows, as in a table, and the first column shows the tree, with the items indented under their parents and branches that open and close them. Users can use context menus and drag-and-drop to add, remove, and move items, including into and out of other items.

For a slice of structs without children, use a table instead. For a tree of nodes without columns, use a tree.

Properties

You can make a tree table from a pointer to a slice of pointers to structs, where the children of an item are in its field named Children:

type task struct {
    Name     string
    Done     bool
    Children []*task
}
tasks := []*task{
    {Name: "Work", Children: []*task{{Name: "Email", Done: true}, {Name: "Report"}}},
    {Name: "Home", Children: []*task{{Name: "Dishes"}}},
}
core.NewTreeTable(b).SetItems(&tasks)

The children can also be in a field with a treetable:"children" struct tag, which can be a []any of pointers to the same struct type, as needed for struct types made with reflect.StructOf. A bool field with a treetable:"closed" struct tag records whether each item is closed, so that it is saved with the items.

You can prevent users from editing a tree table, in which case the left and right arrow keys close and open the selected item:

type task struct {
    Name     string
    Done     bool
    Children []*task
}
tasks := []*task{
    {Name: "Work", Children: []*task{{Name: "Email", Done: true}, {Name: "Report"}}},
    {Name: "Home", Children: []*task{{Name: "Dishes"}}},
}
core.NewTreeTable(b).SetItems(&tasks).SetReadOnly(true)

Dragging items copies them by default, and moves them with Shift. You can set DragMoves to move them by default, and copy them with Shift, as for a table and a tree. The image of the dragged items shows a green plus when they would be copied.

Events

You can detect when a user changes the items of a tree table:

type task struct {
    Name     string
    Done     bool
    Children []*task
}
tasks := []*task{
    {Name: "Work", Children: []*task{{Name: "Email", Done: true}, {Name: "Report"}}},
}
core.NewTreeTable(b).SetItems(&tasks).OnChange(func(e events.Event) {
    core.MessageSnackbar(b, fmt.Sprintf("Tasks under work: %d", len(tasks[0].Children)))
})