Skeleton Loading States (#8719)

* Loading Skeletons

* PR Feedback

packages/bbui/src/Skeleton/Skeleton.svelte

@@ -0,0 +1,56 @@
+<div class="skeleton">
+  <div class="children">
+    <slot />
+  </div>
+</div>
+
+<style>
+  .skeleton {
+    height: 100%;
+    width: 100%;
+    opacity: 0;
+    background-color: var(--spectrum-global-color-gray-300) !important;
+    border-radius: 7px;
+    overflow: hidden;
+    position: relative;
+    animation: fadeIn 130ms ease 0s 1 normal forwards;
+  }
+
+  .children {
+    pointer-events: none;
+    opacity: 0;
+  }
+
+  .skeleton::after {
+    position: absolute;
+    top: 0;
+    right: 0;
+    bottom: 0;
+    left: 0;
+    transform: translateX(-100%);
+    background-image: linear-gradient(
+      90deg,
+      rgba(255, 255, 255, 0) 0,
+      rgba(255, 255, 255, 0.2) 20%,
+      rgba(255, 255, 255, 0.5) 60%,
+      rgba(255, 255, 255, 0)
+    );
+    animation: shimmer 2s infinite;
+    content: "";
+  }
+
+  @keyframes fadeIn {
+    0% {
+      opacity: 0;
+    }
+    100% {
+      opacity: 1;
+    }
+  }
+
+  @keyframes shimmer {
+    100% {
+      transform: translateX(100%);
+    }
+  }
+</style>

packages/bbui/src/Table/Table.svelte

@@ -71,7 +71,8 @@
     visibleRowCount,
     rowCount,
     totalRowCount,
-    rowHeight
+    rowHeight,
+    loading
   )
   $: sortedRows = sortRows(rows, sortColumn, sortOrder)
   $: gridStyle = getGridStyle(fields, schema, showEditColumn)
@@ -120,8 +121,12 @@
     visibleRowCount,
     rowCount,
     totalRowCount,
-    rowHeight
+    rowHeight,
+    loading
   ) => {
+    if (loading) {
+      return `height: ${headerHeight + visibleRowCount * rowHeight}px;`
+    }
     if (!rowCount || !visibleRowCount || totalRowCount <= rowCount) {
       return ""
     }
@@ -277,9 +282,11 @@
   bind:offsetHeight={height}
   style={`--row-height: ${rowHeight}px; --header-height: ${headerHeight}px;`}
 >
-  {#if !loaded}
+  {#if loading}
     <div class="loading" style={heightStyle}>
+      <slot name="loadingIndicator">
         <ProgressCircle />
+      </slot>
     </div>
   {:else}
     <div class="spectrum-Table" style={`${heightStyle}${gridStyle}`}>
@@ -438,9 +445,10 @@
 
   /* Loading */
   .loading {
-    display: grid;
+    display: flex;
-    place-items: center;
+    align-items: center;
     min-height: 100px;
+    justify-content: center;
   }
 
   /* Table */

packages/bbui/src/index.js

@@ -4,6 +4,7 @@ import "./bbui.css"
 import "@spectrum-css/icon/dist/index-vars.css"
 
 // Components
+export { default as Skeleton } from "./Skeleton/Skeleton.svelte"
 export { default as Input } from "./Form/Input.svelte"
 export { default as Stepper } from "./Form/Stepper.svelte"
 export { default as TextArea } from "./Form/TextArea.svelte"

packages/client/manifest.json

@@ -284,7 +284,7 @@
     "editable": true,
     "size": {
       "width": 105,
-      "height": 35
+      "height": 32
     },
     "settings": [
       {
@@ -683,7 +683,7 @@
     "editable": true,
     "size": {
       "width": 400,
-      "height": 30
+      "height": 24
     },
     "settings": [
       {
@@ -808,7 +808,7 @@
     "editable": true,
     "size": {
       "width": 400,
-      "height": 40
+      "height": 32
     },
     "settings": [
       {
@@ -2447,6 +2447,7 @@
     ]
   },
   "stringfield": {
+    "skeleton": false,
     "name": "Text Field",
     "icon": "Text",
     "styles": [
@@ -2455,7 +2456,7 @@
     "editable": true,
     "size": {
       "width": 400,
-      "height": 50
+      "height": 32
     },
     "settings": [
       {
@@ -2538,6 +2539,7 @@
     ]
   },
   "numberfield": {
+    "skeleton": false,
     "name": "Number Field",
     "icon": "123",
     "styles": [
@@ -2652,6 +2654,7 @@
     ]
   },
   "optionsfield": {
+    "skeleton": false,
     "name": "Options Picker",
     "icon": "Menu",
     "styles": [
@@ -2820,6 +2823,7 @@
     ]
   },
   "multifieldselect": {
+    "skeleton": false,
     "name": "Multi-select Picker",
     "icon": "ViewList",
     "styles": [
@@ -2982,12 +2986,13 @@
     ]
   },
   "booleanfield": {
+    "skeleton": false,
     "name": "Checkbox",
     "icon": "SelectBox",
     "editable": true,
     "size": {
-      "width": 400,
+      "width": 20,
-      "height": 50
+      "height": 20
     },
     "settings": [
       {
@@ -3139,6 +3144,7 @@
     ]
   },
   "datetimefield": {
+    "skeleton": false,
     "name": "Date Picker",
     "icon": "Date",
     "styles": [
@@ -3220,6 +3226,7 @@
     ]
   },
   "codescanner": {
+    "skeleton": false,
     "name": "Barcode/QR Scanner",
     "icon": "Camera",
     "styles": [
@@ -3385,6 +3392,7 @@
     ]
   },
   "attachmentfield": {
+    "skeleton": false,
     "name": "Attachment",
     "icon": "Attach",
     "styles": [
@@ -3443,6 +3451,7 @@
     ]
   },
   "relationshipfield": {
+    "skeleton": false,
     "name": "Relationship Picker",
     "icon": "TaskList",
     "styles": [
@@ -3506,6 +3515,7 @@
     ]
   },
   "jsonfield": {
+    "skeleton": false,
     "name": "JSON Field",
     "icon": "Brackets",
     "styles": [
@@ -3707,6 +3717,7 @@
     }
   },
   "table": {
+    "skeleton": false,
     "name": "Table",
     "icon": "Table",
     "illegalChildren": [

packages/client/src/components/BlockComponent.svelte

@@ -23,6 +23,7 @@
   // to render this part of the block, taking advantage of binding enrichment
   $: id = `${block.id}-${context ?? rand}`
   $: instance = {
+    _blockElementHasChildren: $$slots?.default ?? false,
     _component: `@budibase/standard-components/${type}`,
     _id: id,
     _instanceName: type[0].toUpperCase() + type.slice(1),

packages/client/src/components/Component.svelte

@@ -29,6 +29,7 @@
   import Placeholder from "components/app/Placeholder.svelte"
   import ScreenPlaceholder from "components/app/ScreenPlaceholder.svelte"
   import ComponentPlaceholder from "components/app/ComponentPlaceholder.svelte"
+  import Skeleton from "components/app/Skeleton.svelte"
 
   export let instance = {}
   export let isLayout = false
@@ -38,6 +39,7 @@
 
   // Get parent contexts
   const context = getContext("context")
+  const loading = getContext("loading")
   const insideScreenslot = !!getContext("screenslot")
 
   // Create component context
@@ -470,9 +472,21 @@
       componentStore.actions.unregisterInstance(id)
     }
   })
+
+  $: showSkeleton =
+    $loading &&
+    definition.name !== "Screenslot" &&
+    children.length === 0 &&
+    !instance._blockElementHasChildren &&
+    definition.skeleton !== false
 </script>
 
-{#if constructor && initialSettings && (visible || inSelectedPath) && !builderHidden}
+{#if showSkeleton}
+  <Skeleton
+    height={initialSettings?.height || definition?.size?.height || 0}
+    width={initialSettings?.width || definition?.size?.width || 0}
+  />
+{:else if constructor && initialSettings && (visible || inSelectedPath) && !builderHidden}
   <!-- The ID is used as a class because getElementsByClassName is O(1) -->
   <!-- and the performance matters for the selection indicators -->
   <div

packages/client/src/components/Router.svelte

@@ -1,4 +1,5 @@
 <script>
+  import { writable } from "svelte/store"
   import { setContext, getContext, onMount } from "svelte"
   import Router, { querystring } from "svelte-spa-router"
   import { routeStore, stateStore } from "stores"
@@ -9,6 +10,9 @@
   const component = getContext("component")
   setContext("screenslot", true)
 
+  const loading = writable(false)
+  setContext("loading", loading)
+
   // Only wrap this as an array to take advantage of svelte keying,
   // to ensure the svelte-spa-router is fully remounted when route config
   // changes

packages/client/src/components/app/DataProvider.svelte

@@ -1,6 +1,7 @@
 <script>
-  import { getContext } from "svelte"
+  import { writable } from "svelte/store"
-  import { ProgressCircle, Pagination } from "@budibase/bbui"
+  import { setContext, getContext } from "svelte"
+  import { Pagination } from "@budibase/bbui"
   import { fetchData, LuceneUtils } from "@budibase/frontend-core"
 
   export let dataSource
@@ -10,6 +11,8 @@
   export let limit
   export let paginate
 
+  const loading = writable(false)
+
   const { styleable, Provider, ActionTypes, API } = getContext("sdk")
   const component = getContext("component")
 
@@ -77,9 +80,13 @@
       sortColumn: $fetch.sortColumn,
       sortOrder: $fetch.sortOrder,
     },
-    loaded: $fetch.loaded,
+    limit: limit,
   }
 
+  const parentLoading = getContext("loading")
+  setContext("loading", loading)
+  $: loading.set($parentLoading || !$fetch.loaded)
+
   const createFetch = datasource => {
     return fetchData({
       API,
@@ -127,11 +134,6 @@
 
 <div use:styleable={$component.styles} class="container">
   <Provider {actions} data={dataContext}>
-    {#if !$fetch.loaded}
-      <div class="loading">
-        <ProgressCircle />
-      </div>
-    {:else}
     <slot />
     {#if paginate && $fetch.supportsPagination}
       <div class="pagination">
@@ -144,7 +146,6 @@
         />
       </div>
     {/if}
-    {/if}
   </Provider>
 </div>
 
@@ -155,13 +156,6 @@
     justify-content: flex-start;
     align-items: stretch;
   }
-  .loading {
-    display: flex;
-    flex-direction: row;
-    justify-content: center;
-    align-items: center;
-    height: 100px;
-  }
   .pagination {
     display: flex;
     flex-direction: row;

packages/client/src/components/app/Repeater.svelte

@@ -12,22 +12,25 @@
 
   const { Provider } = getContext("sdk")
   const component = getContext("component")
+  const loading = getContext("loading")
 
-  $: rows = dataProvider?.rows ?? []
+  // If the parent DataProvider is loading, fill the rows array with a number of empty objects corresponding to the DataProvider's page size; this allows skeleton loader components to be rendered further down the tree.
-  $: loaded = dataProvider?.loaded ?? true
+  $: rows = $loading
+    ? new Array(dataProvider.limit > 20 ? 20 : dataProvider.limit).fill({})
+    : dataProvider?.rows
 </script>
 
 <Container {direction} {hAlign} {vAlign} {gap} wrap>
   {#if $component.empty}
     <Placeholder />
-  {:else if rows.length > 0}
+  {:else if !$loading && rows.length === 0}
+    <div class="noRows"><i class="ri-list-check-2" />{noRowsMessage}</div>
+  {:else}
     {#each rows as row, index}
       <Provider data={{ ...row, index }}>
         <slot />
       </Provider>
     {/each}
-  {:else if loaded && noRowsMessage}
-    <div class="noRows"><i class="ri-list-check-2" />{noRowsMessage}</div>
   {/if}
 </Container>
 

packages/client/src/components/app/Skeleton.svelte

@@ -0,0 +1,31 @@
+<script>
+  import { getContext } from "svelte"
+  import { Skeleton } from "@budibase/bbui"
+
+  const { styleable } = getContext("sdk")
+  const component = getContext("component")
+
+  export let height
+  export let width
+
+  let styles
+
+  $: {
+    styles = JSON.parse(JSON.stringify($component.styles))
+
+    if (!styles.normal.height && height) {
+      // The height and width props provided to this component can either be numbers or strings set by users (ex. '100%', '100px', '100'). A string of '100' wouldn't be a valid CSS property, but some of our components respect that input, so we need to handle it here also, hence the `!isNaN` check.
+      styles.normal.height = !isNaN(height) ? `${height}px` : height
+    }
+
+    if (!styles.normal.width && width) {
+      styles.normal.width = !isNaN(width) ? `${width}px` : width
+    }
+  }
+</script>
+
+<div use:styleable={styles}>
+  <Skeleton>
+    <slot />
+  </Skeleton>
+</div>

packages/client/src/components/app/forms/AttachmentField.svelte

@@ -76,6 +76,7 @@
   bind:fieldApi
   defaultValue={[]}
 >
+  <div class="minHeightWrapper">
     {#if fieldState}
       <CoreDropzone
         value={fieldState.value}
@@ -90,4 +91,11 @@
         {extensions}
       />
     {/if}
+  </div>
 </Field>
+
+<style>
+  .minHeightWrapper {
+    min-height: 220px;
+  }
+</style>

packages/client/src/components/app/forms/Field.svelte

@@ -1,6 +1,7 @@
 <script>
   import Placeholder from "../Placeholder.svelte"
   import FieldGroupFallback from "./FieldGroupFallback.svelte"
+  import Skeleton from "../Skeleton.svelte"
   import { getContext, onDestroy } from "svelte"
 
   export let label
@@ -53,6 +54,8 @@
     builderStore.actions.updateProp("label", e.target.textContent)
   }
 
+  const loading = getContext("loading")
+
   onDestroy(() => {
     fieldApi?.deregister()
     unsubscribe?.()
@@ -76,6 +79,10 @@
     <div class="spectrum-Form-itemField">
       {#if !formContext}
         <Placeholder text="Form components need to be wrapped in a form" />
+      {:else if $loading}
+        <Skeleton>
+          <slot />
+        </Skeleton>
       {:else if !fieldState}
         <Placeholder />
       {:else if schemaType && schemaType !== type && type !== "options"}

packages/client/src/components/app/table/Table.svelte

@@ -1,6 +1,6 @@
 <script>
   import { getContext } from "svelte"
-  import { Table } from "@budibase/bbui"
+  import { Table, Skeleton } from "@budibase/bbui"
   import SlotRenderer from "./SlotRenderer.svelte"
   import { UnsortableTypes } from "../../../constants"
   import { onDestroy } from "svelte"
@@ -18,6 +18,7 @@
   export let allowSelectRows
   export let compact
 
+  const loading = getContext("loading")
   const component = getContext("component")
   const { styleable, getAction, ActionTypes, routeStore, rowSelectionStore } =
     getContext("sdk")
@@ -30,7 +31,6 @@
   ]
   let selectedRows = []
   $: hasChildren = $component.children
-  $: loading = dataProvider?.loading ?? false
   $: data = dataProvider?.rows || []
   $: fullSchema = dataProvider?.schema ?? {}
   $: fields = getFields(fullSchema, columns, showAutoColumns)
@@ -140,7 +140,7 @@
   <Table
     {data}
     {schema}
-    {loading}
+    loading={$loading}
     {rowCount}
     {quiet}
     {compact}
@@ -155,6 +155,9 @@
     on:sort={onSort}
     on:click={onClick}
   >
+    <div class="skeleton" slot="loadingIndicator">
+      <Skeleton />
+    </div>
     <slot />
   </Table>
   {#if allowSelectRows && selectedRows.length}
@@ -169,6 +172,11 @@
     background-color: var(--spectrum-alias-background-color-secondary);
   }
 
+  .skeleton {
+    height: 100%;
+    width: 100%;
+  }
+
   .row-count {
     margin-top: var(--spacing-l);
   }