为什么我可以在此小部件上使用get_children_by_id（）

Question

我想访问内部小部件，但它给了我一个错误，我无法索引零值。

我的小部件：

local previewWidget = wibox()

previewWidget:setup {
    widget = wibox.widget {
        {
            widget = wibox.widget {
                {
                    widget = awful.widget.clienticon,
                    client = "", 
                    id = "clientIcon"
                },
                {
                    widget = wibox.widget.textbox,
                    id = "titleText"
                },
                nil
            },
            layout = wibox.layout.align.horizontal,
            id = "titleBox"
        },
        {
            widget = wibox.widget.imagebox,
            id = "clientImage"
        },
        nil
    },  
    id = "previewBox",
    layout = wibox.layout.align.vertical,
    border_width = 10, 
    border_color = "FF0000",
}

此命令没有给出错误：

local previewBox = previewWidget:get_children_by_id("previewBox")[1]

但这确实：

local titleBox = previewWidget:get_children_by_id("titleBox")[1]
local clientIcon = previewWidget:get_children_by_id("clientIcon")[1]

我在这里做错了什么？

Answer 1

local previewWidget = wibox.widget {
    {
        {
            widget = awful.widget.clienticon,
            client = "",
            id = "clientIcon"
        },
        {
            widget = wibox.widget.textbox,
            id = "titleText"
        },
        nil,

        layout = wibox.layout.align.horizontal,
        id = "titleBox"
    },
    {
        widget = wibox.widget.imagebox,
        id = "clientImage"
    },
    nil,

    layout = wibox.layout.align.vertical,
    id = "previewBox",
}

我错误地使用了布局：
所有3个小部件都必须是布局称为

local some_widget = wibox.widget {
   { widget nr.1 },
   { widget nr.2 },
   { widget nr.3 },
   layout = wibox.layout.align.vertical
}

P.S.这足以声明没有小部件的布局