Refactor app preview event sending to support async callbacks in client library

packages/builder/src/pages/builder/app/[application]/design/[screenId]/_components/AppPreview.svelte

@@ -103,7 +103,7 @@
   )
 
   // Register handler to send custom to the preview
-  $: store.actions.preview.registerEventHandler((name, payload) => {
+  $: sendPreviewEvent = (name, payload) => {
     iframe?.contentWindow.postMessage(
       JSON.stringify({
         name,
@@ -112,16 +112,38 @@
         runtimeEvent: true,
       })
     )
-  })
+  }
+  $: store.actions.preview.registerEventHandler(sendPreviewEvent)
 
   // Update the iframe with the builder info to render the correct preview
   const refreshContent = message => {
     iframe?.contentWindow.postMessage(message)
   }
 
-  const receiveMessage = message => {
+  const receiveMessage = async message => {
-    const handlers = {
+    if (!message?.data?.type) {
-      [MessageTypes.READY]: () => {
+      return
+    }
+
+    // Await the event handler
+    try {
+      await handleBudibaseEvent(message)
+    } catch (error) {
+      notifications.error(error || "Error handling event from app preview")
+    }
+
+    // Reply that the event has been completed
+    if (message.data?.id) {
+      sendPreviewEvent("event-completed", message.data?.id)
+    }
+  }
+
+  const handleBudibaseEvent = async event => {
+    const { type, data } = event.data || event.detail
+    if (!type) {
+      return
+    }
+    if (type === MessageTypes.READY) {
       // Initialise the app when mounted
       if ($store.clientFeatures.messagePassing) {
         if (!loading) return
@@ -133,26 +155,11 @@
         loading = false
       }
       refreshContent(json)
-      },
+    } else if (type === MessageTypes.ERROR) {
-      [MessageTypes.ERROR]: event => {
       // Catch any app errors
       loading = false
       error = event.error || "An unknown error occurred"
-      },
+    } else if (type === "select-component" && data.id) {
-    }
-
-    const messageHandler = handlers[message.data.type] || handleBudibaseEvent
-    messageHandler(message)
-  }
-
-  const handleBudibaseEvent = async event => {
-    const { type, data } = event.data || event.detail
-    if (!type) {
-      return
-    }
-
-    try {
-      if (type === "select-component" && data.id) {
       $store.selectedComponentId = data.id
       if (!$isActive("./components")) {
         $goto("./components")
@@ -225,9 +232,6 @@
     } else {
       console.warn(`Client sent unknown event type: ${type}`)
     }
-    } catch (error) {
-      notifications.error(error || "Error handling event from app preview")
-    }
   }
 
   const confirmDeleteComponent = componentId => {
@@ -259,42 +263,10 @@
 
   onMount(() => {
     window.addEventListener("message", receiveMessage)
-    if (!$store.clientFeatures.messagePassing) {
-      // Legacy - remove in later versions of BB
-      iframe.contentWindow.addEventListener(
-        "ready",
-        () => {
-          receiveMessage({ data: { type: MessageTypes.READY } })
-        },
-        { once: true }
-      )
-      iframe.contentWindow.addEventListener(
-        "error",
-        event => {
-          receiveMessage({
-            data: { type: MessageTypes.ERROR, error: event.detail },
-          })
-        },
-        { once: true }
-      )
-      // Add listener for events sent by client library in preview
-      iframe.contentWindow.addEventListener("bb-event", handleBudibaseEvent)
-    }
   })
 
-  // Remove all iframe event listeners on component destroy
   onDestroy(() => {
     window.removeEventListener("message", receiveMessage)
-
-    if (iframe.contentWindow) {
-      if (!$store.clientFeatures.messagePassing) {
-        // Legacy - remove in later versions of BB
-        iframe.contentWindow.removeEventListener(
-          "bb-event",
-          handleBudibaseEvent
-        )
-      }
-    }
   })
 </script>
 

packages/client/src/components/preview/DNDHandler.svelte

@@ -22,6 +22,9 @@
   $: target = $dndStore.target
   $: drop = $dndStore.drop
 
+  // Local flag for whether we are awaiting an async drop event
+  let dropping = false
+
   const insideGrid = e => {
     return e.target
       ?.closest?.(".component")
@@ -48,6 +51,10 @@
 
   // Callback when drag stops (whether dropped or not)
   const stopDragging = () => {
+    if (dropping) {
+      return
+    }
+
     // Reset listener
     if (source?.id) {
       const component = document.getElementsByClassName(source?.id)[0]
@@ -57,10 +64,8 @@
     }
 
     // Reset state
-    if (!$dndStore.dropped) {
     dndStore.actions.reset()
   }
-  }
 
   // Callback when initially starting a drag on a draggable component
   const onDragStart = e => {
@@ -253,18 +258,21 @@
   }
 
   // Callback when dropping a drag on top of some component
-  const onDrop = () => {
+  const onDrop = async () => {
     if (!source || !drop?.parent || drop?.index == null) {
       return
     }
 
     // Check if we're adding a new component rather than moving one
     if (source.newComponentType) {
-      builderStore.actions.dropNewComponent(
+      dropping = true
+      await builderStore.actions.dropNewComponent(
         source.newComponentType,
         drop.parent,
         drop.index
       )
+      dropping = false
+      stopDragging()
       return
     }
 
@@ -301,12 +309,14 @@
     }
 
     if (legacyDropTarget && legacyDropMode) {
-      dndStore.actions.markDropped()
+      dropping = true
-      builderStore.actions.moveComponent(
+      await builderStore.actions.moveComponent(
         source.id,
         legacyDropTarget,
         legacyDropMode
       )
+      dropping = false
+      stopDragging()
     }
   }
 

packages/client/src/index.js

@@ -7,6 +7,7 @@ import {
   componentStore,
   environmentStore,
   dndStore,
+  eventStore,
 } from "./stores"
 import loadSpectrumIcons from "@budibase/bbui/spectrum-icons-rollup.js"
 import { get } from "svelte/store"
@@ -42,9 +43,9 @@ const loadBudibase = async () => {
   })
 
   // Reset DND state if we completed a successful drop
-  if (get(dndStore).dropped) {
+  // if (get(dndStore).dropped) {
-    dndStore.actions.reset()
+  //   dndStore.actions.reset()
-  }
+  // }
 
   // Set app ID - this window flag is set by both the preview and the real
   // server rendered app HTML
@@ -59,15 +60,17 @@ const loadBudibase = async () => {
   devToolsStore.actions.setEnabled(enableDevTools)
 
   // Register handler for runtime events from the builder
-  window.handleBuilderRuntimeEvent = (name, payload) => {
+  window.handleBuilderRuntimeEvent = (type, data) => {
     if (!window["##BUDIBASE_IN_BUILDER##"]) {
       return
     }
-    if (name === "eject-block") {
+    if (type === "event-completed") {
-      const block = blockStore.actions.getBlock(payload)
+      eventStore.actions.resolveEvent(data)
+    } else if (type === "eject-block") {
+      const block = blockStore.actions.getBlock(data)
       block?.eject()
-    } else if (name === "dragging-new-component") {
+    } else if (type === "dragging-new-component") {
-      const { dragging, component } = payload
+      const { dragging, component } = data
       if (dragging) {
         const definition =
           componentStore.actions.getComponentDefinition(component)

packages/client/src/stores/builder.js

@@ -1,10 +1,7 @@
 import { writable, get } from "svelte/store"
 import { API } from "api"
 import { devToolsStore } from "./devTools.js"
-
+import { eventStore } from "./events.js"
-const dispatchEvent = (type, data = {}) => {
-  window.parent.postMessage({ type, data })
-}
 
 const createBuilderStore = () => {
   const initialState = {
@@ -19,6 +16,7 @@ const createBuilderStore = () => {
     navigation: null,
     hiddenComponentIds: [],
     usedPlugins: null,
+    eventResolvers: {},
 
     // Legacy - allow the builder to specify a layout
     layout: null,
@@ -35,25 +33,25 @@ const createBuilderStore = () => {
         selectedComponentId: id,
       }))
       devToolsStore.actions.setAllowSelection(false)
-      dispatchEvent("select-component", { id })
+      eventStore.actions.dispatchEvent("select-component", { id })
     },
     updateProp: (prop, value) => {
-      dispatchEvent("update-prop", { prop, value })
+      eventStore.actions.dispatchEvent("update-prop", { prop, value })
     },
     updateStyles: (styles, id) => {
-      dispatchEvent("update-styles", { styles, id })
+      eventStore.actions.dispatchEvent("update-styles", { styles, id })
     },
     keyDown: (key, ctrlKey) => {
-      dispatchEvent("key-down", { key, ctrlKey })
+      eventStore.actions.dispatchEvent("key-down", { key, ctrlKey })
     },
     duplicateComponent: id => {
-      dispatchEvent("duplicate-component", { id })
+      eventStore.actions.dispatchEvent("duplicate-component", { id })
     },
     deleteComponent: id => {
-      dispatchEvent("delete-component", { id })
+      eventStore.actions.dispatchEvent("delete-component", { id })
     },
     notifyLoaded: () => {
-      dispatchEvent("preview-loaded")
+      eventStore.actions.dispatchEvent("preview-loaded")
     },
     analyticsPing: async () => {
       try {
@@ -62,15 +60,15 @@ const createBuilderStore = () => {
         // Do nothing
       }
     },
-    moveComponent: (componentId, destinationComponentId, mode) => {
+    moveComponent: async (componentId, destinationComponentId, mode) => {
-      dispatchEvent("move-component", {
+      await eventStore.actions.dispatchEvent("move-component", {
         componentId,
         destinationComponentId,
         mode,
       })
     },
     dropNewComponent: (component, parent, index) => {
-      dispatchEvent("drop-new-component", {
+      eventStore.actions.dispatchEvent("drop-new-component", {
         component,
         parent,
         index,
@@ -83,16 +81,16 @@ const createBuilderStore = () => {
       store.update(state => ({ ...state, editMode: enabled }))
     },
     clickNav: () => {
-      dispatchEvent("click-nav")
+      eventStore.actions.dispatchEvent("click-nav")
     },
     requestAddComponent: () => {
-      dispatchEvent("request-add-component")
+      eventStore.actions.dispatchEvent("request-add-component")
     },
     highlightSetting: setting => {
-      dispatchEvent("highlight-setting", { setting })
+      eventStore.actions.dispatchEvent("highlight-setting", { setting })
     },
     ejectBlock: (id, definition) => {
-      dispatchEvent("eject-block", { id, definition })
+      eventStore.actions.dispatchEvent("eject-block", { id, definition })
     },
     updateUsedPlugin: (name, hash) => {
       // Check if we used this plugin
@@ -109,7 +107,7 @@ const createBuilderStore = () => {
       }
 
       // Notify the builder so we can reload component definitions
-      dispatchEvent("reload-plugin")
+      eventStore.actions.dispatchEvent("reload-plugin")
     },
   }
   return {

packages/client/src/stores/dnd.js

@@ -11,9 +11,6 @@ const createDndStore = () => {
 
     // Info about where the component would be dropped
     drop: null,
-
-    // Whether the current drop has been completed successfully
-    dropped: false,
   }
   const store = writable(initialState)
 
@@ -63,13 +60,6 @@ const createDndStore = () => {
     store.set(initialState)
   }
 
-  const markDropped = () => {
-    store.update(state => {
-      state.dropped = true
-      return state
-    })
-  }
-
   return {
     subscribe: store.subscribe,
     actions: {
@@ -78,7 +68,6 @@ const createDndStore = () => {
       updateTarget,
       updateDrop,
       reset,
-      markDropped,
     },
   }
 }
@@ -91,7 +80,6 @@ export const dndStore = createDndStore()
 // or components which depend on DND state unless values actually change.
 export const dndParent = computed(dndStore, x => x.drop?.parent)
 export const dndIndex = computed(dndStore, x => x.drop?.index)
-export const dndDropped = computed(dndStore, x => x.dropped)
 export const dndBounds = computed(dndStore, x => x.source?.bounds)
 export const dndIsDragging = computed(dndStore, x => !!x.source)
 export const dndIsNewComponent = computed(

packages/client/src/stores/events.js

@@ -0,0 +1,31 @@
+import { writable, get } from "svelte/store"
+
+const createEventStore = () => {
+  const initialState = {
+    eventResolvers: {},
+  }
+  const store = writable(initialState)
+
+  const actions = {
+    dispatchEvent: (type, data) => {
+      const id = Math.random()
+      return new Promise(resolve => {
+        window.parent.postMessage({ type, data, id })
+        store.update(state => {
+          state.eventResolvers[id] = resolve
+          return state
+        })
+      })
+    },
+    resolveEvent: data => {
+      get(store).eventResolvers[data]?.()
+    },
+  }
+
+  return {
+    subscribe: store.subscribe,
+    actions,
+  }
+}
+
+export const eventStore = createEventStore()

packages/client/src/stores/index.js

@@ -15,6 +15,7 @@ export { uploadStore } from "./uploads.js"
 export { rowSelectionStore } from "./rowSelection.js"
 export { blockStore } from "./blocks.js"
 export { environmentStore } from "./environment"
+export { eventStore } from "./events.js"
 export {
   dndStore,
   dndIndex,
@@ -22,7 +23,6 @@ export {
   dndBounds,
   dndIsNewComponent,
   dndIsDragging,
-  dndDropped,
 } from "./dnd"
 
 // Context stores are layered and duplicated, so it is not a singleton

packages/client/src/stores/screens.js

@@ -2,13 +2,7 @@ import { derived } from "svelte/store"
 import { routeStore } from "./routes"
 import { builderStore } from "./builder"
 import { appStore } from "./app"
-import {
+import { dndIndex, dndParent, dndIsNewComponent, dndBounds } from "./dnd.js"
-  dndIndex,
-  dndParent,
-  dndIsNewComponent,
-  dndBounds,
-  dndDropped,
-} from "./dnd.js"
 import { RoleUtils } from "@budibase/frontend-core"
 import { findComponentById, findComponentParent } from "../utils/components.js"
 import { Helpers } from "@budibase/bbui"
@@ -24,7 +18,6 @@ const createScreenStore = () => {
       dndIndex,
       dndIsNewComponent,
       dndBounds,
-      dndDropped,
     ],
     ([
       $appStore,
@@ -34,7 +27,6 @@ const createScreenStore = () => {
       $dndIndex,
       $dndIsNewComponent,
       $dndBounds,
-      $dndDropped,
     ]) => {
       let activeLayout, activeScreen
       let screens
@@ -80,9 +72,6 @@ const createScreenStore = () => {
           activeScreen.props,
           selectedComponentId
         )
-        const selectedComponent = selectedParent?._children?.find(
-          x => x._id === selectedComponentId
-        )
 
         // Remove selected component from tree if we are moving an existing
         // component
@@ -92,13 +81,8 @@ const createScreenStore = () => {
           )
         }
 
-        // Insert placeholder component if dragging, or artificially insert
+        // Insert placeholder component
-        // the dropped component in the new location if the drop completed
+        const componentToInsert = {
-        let componentToInsert
-        if ($dndDropped && !$dndIsNewComponent) {
-          componentToInsert = selectedComponent
-        } else {
-          componentToInsert = {
           _component: "@budibase/standard-components/container",
           _id: DNDPlaceholderID,
           _styles: {
@@ -110,8 +94,6 @@ const createScreenStore = () => {
           },
           static: true,
         }
-        }
-        if (componentToInsert) {
         let parent = findComponentById(activeScreen.props, $dndParent)
         if (parent) {
           if (!parent._children?.length) {
@@ -121,7 +103,6 @@ const createScreenStore = () => {
           }
         }
       }
-      }
 
       // Assign ranks to screens, preferring higher roles and home screens
       screens.forEach(screen => {