Store the state of DomainListInterface in its parent. IT WORKS!

src/App/Container.purs

@@ -166,6 +166,10 @@ handleAction = case _ of
     DomainListInterface.MessageToSend message  -> H.tell _ws_dns unit (WS.ToSend message)
     DomainListInterface.Log message            -> H.tell _log unit (Log.Log message)
     DomainListInterface.DNSManagerReconnect    -> handleAction AuthenticateToDNSManager
+    DomainListInterface.StoreState s           -> H.modify_ _ { store_DomainListInterface_state = Just s }
+    DomainListInterface.AskState               -> do
+      state <- H.get
+      H.tell _dli unit (DomainListInterface.ProvideState state.store_DomainListInterface_state)
 
   -- TODO: depending on the current page, we should provide the received message to different components.
   AuthenticationDaemonEvent ev -> case ev of

src/App/DomainListInterface.purs

@@ -1,5 +1,3 @@
-module App.DomainListInterface where
-
 -- | `App.DomainListInterface` is a simple component with the list of own domains
 -- | and a form to add a new domain.
 -- |
@@ -11,6 +9,8 @@ module App.DomainListInterface where
 -- |   - TODO: ask for confirmation
 -- |   - TODO: switch to the interface to show and modify the content of a Zone
 
+module App.DomainListInterface where
+
 import Prelude (Unit, bind, discard, map, otherwise, pure, ($), (/=), (<<<), (<>))
 
 import CSSClasses as CSSClasses
@@ -37,20 +37,33 @@ import App.Messages.DNSManagerDaemon as DNSManager
 -- |
 -- | Also, this component can log messages and ask its parent (`App.Container`) to
 -- | reconnect the websocket to `dnsmanagerd`.
+-- |
+-- | Finally, the component can ask its state to its parent.
+-- | The reason is quite simple.
+-- | The component can be deleted, meaning that it loses its state.
+-- | Instead of asking `dnsmanagerd` the list of available domains and the list of owned domains
+-- | each time the component is instanciated, the parent stores the component's state when the
+-- | component is removed. This way, the data is conserved.
 
 data Output
   = MessageToSend ArrayBuffer
   | Log LogMessage
   | DNSManagerReconnect
+  | AskState
+  | StoreState State
 
 -- | `App.DomainListInterface` can receive messages from `dnsmanagerd`.
 -- |
 -- | The component is also informed when the connection is lost or up again.
+-- |
+-- | Finally, its entire state can be provided by its parent.
+-- | See the explanation for the `Output` data type.
 
 data Query a
   = MessageReceived ArrayBuffer a
   | ConnectionIsDown a
   | ConnectionIsUp a
+  | ProvideState (Maybe State) a
 
 type Slot = H.Slot Query Output
 
@@ -83,6 +96,9 @@ data Action
   | RemoveDomain String
   | EnterDomain String
 
+  | Initialize
+  | Finalize
+
 -- | The form only has two elements:
 -- | the subdomain name input and the selected TLD.
 
@@ -108,8 +124,10 @@ component =
     { initialState
     , render
     , eval: H.mkEval $ H.defaultEval
-        { handleAction = handleAction
+        { initialize   = Just Initialize
+        , handleAction = handleAction
         , handleQuery  = handleQuery
+        , finalize     = Just Finalize
         }
     }
 
@@ -177,6 +195,13 @@ render { accepted_domains, my_domains, newDomainForm, wsUp }
 
 handleAction :: forall m. MonadAff m => Action -> H.HalogenM State Action () Output m Unit
 handleAction = case _ of
+  Initialize -> do
+    H.raise $ AskState
+
+  Finalize -> do
+    state <- H.get
+    H.raise $ StoreState state
+
   UpdateAcceptedDomains domains -> do
     H.modify_ _ { accepted_domains = domains }
 
@@ -216,6 +241,13 @@ handleAction = case _ of
 handleQuery :: forall a m. MonadAff m => Query a -> H.HalogenM State Action () Output m (Maybe a)
 handleQuery = case _ of
 
+  ProvideState maybe_state a -> do
+    case maybe_state of
+      Nothing -> pure Nothing
+      Just s  -> do
+        H.put s
+        pure (Just a)
+
   MessageReceived message a -> do
     receivedMessage <- H.liftEffect $ DNSManager.deserialize message
     case receivedMessage of