如何使用库（jsTreeR）创建不可编辑的叶节点子集

您必须使用自定义上下文菜单。将类型分配给要不可删除的节点，并在自定义上下文菜单中使用它：

library(jsTreeR)

nodes <- list(
  list(
    text = "Menu",
    state = list(opened = TRUE),
    children = list(
      list(
        text = "this node cannot be deleted",
        type = "undeletable"
      ),
      list(
        text = "B"
      ),
      list(
        text = "C"
      )
    )
  ),
  list(
    text = "Drag here:",
    state = list(opened = TRUE)
  )
)

customMenu <- JS(
  "function customMenu(node) {",
  "  var tree = $('#mytree').jstree(true);", # 'mytree' is the Shiny id or the elementId
  "  var items = {",
  "    'delete' : {",
  "      'label'  : 'Delete',",
  "      'action' : function (obj) { if(node.type !== 'undeletable') tree.delete_node(node); },",
  "      'icon'   : 'glyphicon glyphicon-trash'",
  "     }",
  "  }",
  "  return items;",
  "}")

jstree(
  nodes,
  types = list(undeletable = list()),
  checkCallback = TRUE,
  contextMenu = list(items = customMenu),
  elementId = "mytree" # don't use elementId in Shiny! use the Shiny id
)

这是一个完整的上下文菜单，您必须按上述方式对其进行修改：

customMenu <- JS("function customMenu(node)
{
  var tree = $('#mytree').jstree(true);
  var items = {
    'rename' : {
      'label' : 'Rename',
      'action' : function (obj) { tree.edit(node); },
      'icon': 'glyphicon glyphicon-edit'
    },
    'delete' : {
      'label' : 'Delete',
      'action' : function (obj) { tree.delete_node(node); },
      'icon' : 'glyphicon glyphicon-trash'
    },
    'create' : {
      'label' : 'Create',
      'action' : function (obj) { tree.create_node(node); },
      'icon': 'glyphicon glyphicon-plus'
    }
  }
  return items;
}")

这是另一种方法（基于此处给出的答案），它禁用上下文菜单项，而不是在单击它们后不执行任何操作。

优点是，项目是灰色的。

以下还考虑了不允许删除具有叶节点的分支的问题：

library(jsTreeR)
library(shiny)

nodes <- list(
  list(
    text = "Branch 1",
    state = list(opened = TRUE, disabled = FALSE),
    type = "parent",
    children = list(
      list(text = "Leaf A", type = "undeletable", state = list(disabled = FALSE), data = list(customdata = 1)),
      list(text = "Leaf B", type = "undeletable", state = list(disabled = FALSE), data = list(customdata = 2)),
      list(text = "Leaf C", type = "undeletable", state = list(disabled = FALSE), data = list(customdata = 3)),
      list(text = "Leaf D", type = "undeletable", state = list(disabled = FALSE), data = list(customdata = 4))
    )
  ),
  list(text = "Branch 2", type = "parent", state = list(opened = TRUE))
)

ui <- fluidPage(
  jstreeOutput("mytree")
)

customMenu <- JS(
  "function customMenu(node) {
  var tree = $('#mytree').jstree(true);
  var items = {
    'rename' : {
      'label' : 'Rename',
      'action' : function (obj) { tree.edit(node); },
      'icon': 'glyphicon glyphicon-edit'
    },
    'delete' : {
      'label' : 'Delete',
      'action' : function (obj) { tree.delete_node(node); },
      'icon' : 'glyphicon glyphicon-trash'
    },
    'create' : {
      'label' : 'Create',
      'action' : function (obj) { tree.create_node(node); },
      'icon': 'glyphicon glyphicon-plus'
    }
  }
  
  if (node.children.length > 0) { items.delete._disabled = true; }
  if (node.type === 'undeletable') { items.rename._disabled = true;
                                     items.delete._disabled = true;
                                     items.create._disabled = true;
                                    }

  return items;
}")

server <- function(input, output, session){
  output[["mytree"]] <- renderJstree({
    suppressMessages(jstree(
      nodes,
      search = list(
        show_only_matches = TRUE,
        case_sensitive = FALSE,
        search_leaves_only = FALSE
      ),
      dragAndDrop = TRUE,
      multiple = TRUE,
      contextMenu = list(items = customMenu),
      types = list(default = list(icon = "fa fa-caret-right"), undeletable = list(icon = "fa-solid fa-leaf"), parent = list(icon = "fa-brands fa-pagelines")),
      theme = "proton"
    ))
  })
}  

shinyApp(ui, server)