From 96f378d108274bbff01b425345bc847989f04050 Mon Sep 17 00:00:00 2001
From: Oliver Sand <oliver.sand@sda-se.com>
Date: Thu, 4 Feb 2021 10:54:58 +0100
Subject: [PATCH] Add support for custom empty state of `Table` components

---
 .changeset/violet-maps-occur.md               |  8 ++
 .../src/components/Table/Table.stories.tsx    | 77 ++++++++++++++++---
 .../core/src/components/Table/Table.test.tsx  | 12 +++
 packages/core/src/components/Table/Table.tsx  | 21 +++++
 4 files changed, 109 insertions(+), 9 deletions(-)
 create mode 100644 .changeset/violet-maps-occur.md

diff --git a/.changeset/violet-maps-occur.md b/.changeset/violet-maps-occur.md
new file mode 100644
index 0000000000..e746ca3323
--- /dev/null
+++ b/.changeset/violet-maps-occur.md
@@ -0,0 +1,8 @@
+---
+'@backstage/core': patch
+---
+
+Add support for custom empty state of `Table` components.
+
+You can now optionally pass `emptyComponent` to `Table` that is displayed
+if the table has now rows.
diff --git a/packages/core/src/components/Table/Table.stories.tsx b/packages/core/src/components/Table/Table.stories.tsx
index 4be85e494f..fe3fe89941 100644
--- a/packages/core/src/components/Table/Table.stories.tsx
+++ b/packages/core/src/components/Table/Table.stories.tsx
@@ -14,8 +14,10 @@
  * limitations under the License.
  */
 
+import { makeStyles } from '@material-ui/core';
 import React from 'react';
-import { Table, SubvalueCell, TableColumn } from './';
+import { Link } from '../Link';
+import { SubvalueCell, Table, TableColumn } from './';
 import { TableFilter } from './Table';
 
 export default {
@@ -23,7 +25,16 @@ export default {
   component: Table,
 };
 
-const containerStyle = { width: 850 };
+const useStyles = makeStyles(theme => ({
+  container: {
+    width: 850,
+  },
+  empty: {
+    padding: theme.spacing(2),
+    display: 'flex',
+    justifyContent: 'center',
+  },
+}));
 
 const generateTestData: (number: number) => Array<{}> = (rows = 10) => {
   const data: Array<{}> = [];
@@ -43,6 +54,7 @@ const generateTestData: (number: number) => Array<{}> = (rows = 10) => {
 const testData10 = generateTestData(10);
 
 export const DefaultTable = () => {
+  const classes = useStyles();
   const columns: TableColumn[] = [
     {
       title: 'Column 1',
@@ -66,7 +78,7 @@ export const DefaultTable = () => {
   ];
 
   return (
-    <div style={containerStyle}>
+    <div className={classes.container}>
       <Table
         options={{ paging: false }}
         data={testData10}
@@ -77,7 +89,8 @@ export const DefaultTable = () => {
   );
 };
 
-export const SubtitleTable = () => {
+export const EmptyTable = () => {
+  const classes = useStyles();
   const columns: TableColumn[] = [
     {
       title: 'Column 1',
@@ -101,7 +114,49 @@ export const SubtitleTable = () => {
   ];
 
   return (
-    <div style={containerStyle}>
+    <div className={classes.container}>
+      <Table
+        options={{ paging: false }}
+        data={[]}
+        columns={columns}
+        emptyComponent={
+          <div className={classes.empty}>
+            No data was added yet,&nbsp;
+            <Link to="http://backstage.io/">learn how to add data</Link>.
+          </div>
+        }
+        title="Backstage Table"
+      />
+    </div>
+  );
+};
+
+export const SubtitleTable = () => {
+  const classes = useStyles();
+  const columns: TableColumn[] = [
+    {
+      title: 'Column 1',
+      field: 'col1',
+      highlight: true,
+    },
+    {
+      title: 'Column 2',
+      field: 'col2',
+    },
+    {
+      title: 'Numeric value',
+      field: 'number',
+      type: 'numeric',
+    },
+    {
+      title: 'A Date',
+      field: 'date',
+      type: 'date',
+    },
+  ];
+
+  return (
+    <div className={classes.container}>
       <Table
         options={{ paging: false }}
         data={testData10}
@@ -114,6 +169,7 @@ export const SubtitleTable = () => {
 };
 
 export const HiddenSearchTable = () => {
+  const classes = useStyles();
   const columns: TableColumn[] = [
     {
       title: 'Column 1',
@@ -137,7 +193,7 @@ export const HiddenSearchTable = () => {
   ];
 
   return (
-    <div style={containerStyle}>
+    <div className={classes.container}>
       <Table
         options={{ paging: false, search: false }}
         data={testData10}
@@ -148,6 +204,7 @@ export const HiddenSearchTable = () => {
 };
 
 export const SubvalueTable = () => {
+  const classes = useStyles();
   const columns: TableColumn[] = [
     {
       title: 'Column 1',
@@ -181,13 +238,14 @@ export const SubvalueTable = () => {
   ];
 
   return (
-    <div style={containerStyle}>
+    <div className={classes.container}>
       <Table options={{ paging: false }} data={testData10} columns={columns} />
     </div>
   );
 };
 
 export const DenseTable = () => {
+  const classes = useStyles();
   const columns: TableColumn[] = [
     {
       title: 'Column 1',
@@ -211,7 +269,7 @@ export const DenseTable = () => {
   ];
 
   return (
-    <div style={containerStyle}>
+    <div className={classes.container}>
       <Table
         options={{ paging: false, padding: 'dense' }}
         data={testData10}
@@ -223,6 +281,7 @@ export const DenseTable = () => {
 };
 
 export const FilterTable = () => {
+  const classes = useStyles();
   const columns: TableColumn[] = [
     {
       title: 'Column 1',
@@ -261,7 +320,7 @@ export const FilterTable = () => {
   ];
 
   return (
-    <div style={containerStyle}>
+    <div className={classes.container}>
       <Table
         options={{ paging: false, padding: 'dense' }}
         data={testData10}
diff --git a/packages/core/src/components/Table/Table.test.tsx b/packages/core/src/components/Table/Table.test.tsx
index 48b90be419..3c29f0b65d 100644
--- a/packages/core/src/components/Table/Table.test.tsx
+++ b/packages/core/src/components/Table/Table.test.tsx
@@ -53,4 +53,16 @@ describe('<Table />', () => {
     );
     expect(rendered.getByText('subtitle')).toBeInTheDocument();
   });
+
+  it('renders custom empty component if empty', async () => {
+    const rendered = await renderInTestApp(
+      <Table
+        subtitle="subtitle"
+        emptyComponent={<div>EMPTY</div>}
+        columns={minProps.columns}
+        data={[]}
+      />,
+    );
+    expect(rendered.getByText('EMPTY')).toBeInTheDocument();
+  });
 });
diff --git a/packages/core/src/components/Table/Table.tsx b/packages/core/src/components/Table/Table.tsx
index dbb2964845..033ec01d3c 100644
--- a/packages/core/src/components/Table/Table.tsx
+++ b/packages/core/src/components/Table/Table.tsx
@@ -42,6 +42,7 @@ import MTable, {
   Column,
   Icons,
   MaterialTableProps,
+  MTableBody,
   MTableHeader,
   MTableToolbar,
   Options,
@@ -202,6 +203,7 @@ export interface TableProps<T extends object = {}>
   subtitle?: string;
   filters?: TableFilter[];
   initialState?: TableState;
+  emptyComponent?: JSX.Element;
   onStateChange?: (state: TableState) => any;
 }
 
@@ -212,6 +214,7 @@ export function Table<T extends object = {}>({
   subtitle,
   filters,
   initialState,
+  emptyComponent,
   onStateChange,
   ...props
 }: TableProps<T>) {
@@ -423,6 +426,23 @@ export function Table<T extends object = {}>({
     ],
   );
 
+  const Body = useCallback(
+    bodyProps => {
+      if (emptyComponent && data.length === 0) {
+        return (
+          <tbody>
+            <tr>
+              <td colSpan={columns.length}>{emptyComponent}</td>
+            </tr>
+          </tbody>
+        );
+      }
+
+      return <MTableBody {...bodyProps} />;
+    },
+    [data, emptyComponent, columns],
+  );
+
   return (
     <div className={tableClasses.root}>
       {filtersOpen && data && filters?.length && (
@@ -438,6 +458,7 @@ export function Table<T extends object = {}>({
             <MTableHeader classes={headerClasses} {...headerProps} />
           ),
           Toolbar,
+          Body,
         }}
         options={{ ...defaultOptions, ...options }}
         columns={MTColumns}