qwikchild

---

name: qwikchild description: How to use the QwikAppChild library (--%%file:$fibaro.lib.qwikchild,qwikchild) for managing QuickApp child devices with UID-based addressing, declarative child definitions, per-child UI, internalStorage variables, and UI event routing to children. USE FOR: creating/loading/removing child devices, attaching UI to a child, routing UI callbacks to child methods, persisting child-scoped state, one-shot or declarative child management patterns.

QwikAppChild Library

QwikAppChild is a plua built-in library that extends Fibaro's QuickAppChild with UID-based child management, declarative child definitions, per-child UI support, and automatic UI event routing.

Include It

--%%file:$fibaro.lib.qwikchild,qwikchild

Add this header to your QA file. No require needed — the file is executed on load and registers everything globally.

The library prints QwikAppChild library v2.x.x on load to confirm it is active.

---

Core Concepts

Concept	Description
UID	A stable string ID you assign to each child (e.g. "i1", "sensor_kitchen"). Survives restarts and recreations.
ClassName	The Lua class name of the child ("MySensor"). Stored in the child's internalStorage.
QwikAppChild	Base class — use instead of QuickAppChild for children managed by this library.

---

QuickApp Methods Added by the Library

self:initChildren(children) — declarative, recommended

Creates missing children, loads existing ones, removes children not in the definition table. One call replaces manual create/load/remove logic.

local children = {
  i1 = {
    name       = "Kitchen Sensor",
    type       = "com.fibaro.temperatureSensor",
    className  = "KitchenSensor",
    properties = { value = 20 },
    interfaces = { "battery" },
    store      = { pollInterval = "30" },  -- written to internalStorage
    room       = 5,                        -- HC3 room ID (optional)
    UI         = {                         -- optional per-child UI
      { label="lbl", text="Ready" },
      { button="refresh", text="Refresh", onReleased="refresh" },
    },
  },
  i2 = {
    name      = "Bedroom Sensor",
    type      = "com.fibaro.temperatureSensor",
    className = "BedroomSensor",
  },
}

function QuickApp:onInit()
  quickApp = self
  function self.initChildDevices() end   -- suppress default child init
  self:initChildren(children)
end

UID naming tip: UIDs starting with "i" followed by a digit (e.g. "i1", "i2") are sorted numerically during creation — useful to control creation order.

---

self:createChild(uid, props, className [, UI]) — manual, single child

Creates one child (or recreates it if a child with that UID already exists).

local props = {
  name       = "Hallway Switch",
  type       = "com.fibaro.binarySwitch",
  properties = { value = false },
  interfaces = {},
  store      = {},
}
local UI = {
  { label = "status", text = "Off" },
  { button = "toggle", text = "Toggle", onReleased = "toggle" },
}
local child = self:createChild("hall_sw", props, "HallwaySwitch", UI)

---

self:loadExistingChildren([childrenDefs]) — load without recreating

Loads previously created children from HC3 without modifying them. Pass a definitions table to restrict which UIDs are loaded; omit it to load all children.

function QuickApp:onInit()
  quickApp = self
  function self.initChildDevices() end
  self:loadExistingChildren()   -- load all children found on HC3
end

---

self:createMissingChildren(children) — create only, no removal

Creates children that don't exist yet. Does not remove extras. Useful when you want additive-only management.

---

self:removeUndefinedChildren(childrenDefs) — remove extras

Deletes any child on HC3 whose UID is not in childrenDefs. Called automatically by initChildren.

---

self:getChildrenUidMap() → {uid → {id, className}}

Returns a map of all children found on HC3 for this parent QA.

local map = self:getChildrenUidMap()
for uid, info in pairs(map) do
  print(uid, info.id, info.className)
end

---

QuickApp.setChildRemovedHook(_, fn) — removal callback

Called with the child device ID whenever a child is removed.

QuickApp.setChildRemovedHook(nil, function(id)
  print("child removed:", id)
end)

---

Child Class Definition

Extend QwikAppChild instead of QuickAppChild:

class "MySensor"(QwikAppChild)

function MySensor:__init(device)
  QwikAppChild.__init(self, device)
  -- self._uid       → the UID string assigned at creation
  -- self._className → class name string
  -- self._sid       → numeric suffix of the UID (e.g. 1 for "i1")
  self:debug("MySensor ready, uid:", self._uid)
end

function MySensor:refresh(event)
  self:updateProperty("value", 21.5)
  self:updateView("lbl", "text", "21.5°C")
end

Methods inherited from QuickAppChild (still available)

• self:updateProperty(name, value)
• self:updateView(elementName, property, value)
• self:debug(...) / self:warning(...) / self:error(...)
• self:getVariable(name) / self:setVariable(name, value)
• self:internalStorageGet(key) / self:internalStorageSet(key, value)
• self:callAction(name, ...) — call a method by name

self.parent is set to the parent QuickApp object after the child is initialized.

---

Per-Child UI

Pass a UI table to createChild or inside the initChildren definition. The library converts it to the HC3 uiView and uiCallbacks format automatically.

UI = {
  { label = "status", text = "Idle" },
  { button = "on",  text = "On",  onReleased = "turnOn"  },
  { button = "off", text = "Off", onReleased = "turnOff" },
  { slider = "dim", text = "Dim", min = "0", max = "100", onChanged = "setLevel" },
}

UI callback methods are defined on the child class:

function MySensor:turnOn(event)   self:updateProperty("value", true) end
function MySensor:turnOff(event)  self:updateProperty("value", false) end
function MySensor:setLevel(event) self:updateProperty("value", tonumber(event.values[1])) end

UI event routing — setupUIhandler

The library installs a UIHandler on the parent QA that routes UI events to the correct child object automatically. You do not need to implement UIHandler yourself as long as you use QwikAppChild.

Routing priority for an element named elm:

1. obj[elm](obj, event) — method named exactly after the element
2. obj[uiCallbacks[elm][eventType]](obj, event) — callback registered via uiCallbacks
3. obj[elm.."Clicked"](obj, event) — fallback convenience naming

---

internalStorage Helpers

Per-child key/value storage backed by QA variables on HC3:

-- In child __init or anywhere with the child object:
local interval = self:internalStorageGet("pollInterval")  -- returns nil if not set
self:internalStorageSet("lastSeen", os.date("%Y-%m-%d"))

The store field in a child definition pre-sets keys at creation time:

i1 = {
  ...
  store = { pollInterval = "30", location = "kitchen" },
}

---

Debug Flag

fibaro.debugFlags.qwikchild = true   -- enable verbose library logging (default: true)
fibaro.debugFlags.qwikchild = false  -- silence it

---

Full Minimal Example

--%%name:MultiSensor Hub
--%%type:com.fibaro.deviceController
--%%offline:true
--%%file:$fibaro.lib.qwikchild,qwikchild

class "RoomSensor"(QwikAppChild)

function RoomSensor:__init(device)
  QwikAppChild.__init(self, device)
  self:debug("RoomSensor init, uid:", self._uid)
end

function RoomSensor:refresh(event)
  -- called from button press
  self:updateView("lbl", "text", "Refreshed!")
end

local CHILDREN = {
  i1 = {
    name      = "Kitchen",
    type      = "com.fibaro.temperatureSensor",
    className = "RoomSensor",
    UI = {
      { label = "lbl", text = "Ready" },
      { button = "refresh", text = "Refresh", onReleased = "refresh" },
    },
  },
  i2 = {
    name      = "Bedroom",
    type      = "com.fibaro.temperatureSensor",
    className = "RoomSensor",
  },
}

function QuickApp:onInit()
  quickApp = self
  function self.initChildDevices() end
  self:initChildren(CHILDREN)
end

---

Common Gotchas

• quickApp = self must be set at the top of onInit — the library internally references the quickApp global.
• function self.initChildDevices() end — always suppress the default Fibaro child init to prevent double-init when using this library.
• initChildren recreates children — it deletes any child with a matching UID and creates a fresh one. On a real HC3, child device IDs change on recreation. Use loadExistingChildren if you want to preserve IDs between restarts.
• plua offline mode warning — initChildren prints a warning if running in plua without a state file, because children are re-created on every run (IDs change). Use --%%save:state.json to persist state.
• UID uniqueness — UIDs must be unique within a parent QA. The library uses them as stable identifiers; duplicate UIDs cause the old child to be deleted.