Add support for empty in Reference fields

docs/ReferenceField.md

@@ -74,26 +74,38 @@ It uses `dataProvider.getMany()` instead of `dataProvider.getOne()` [for perform
 | `source`    | Required | `string`            | -        | Name of the property to display |
 | `reference` | Required | `string`            | -        | The name of the resource for the referenced records, e.g. 'posts' |
 | `children`  | Optional | `ReactNode`         | -        | One or more Field elements used to render the referenced record |
-| `emptyText` | Optional | `string`            | ''       | Defines a text to be shown when the field has no value or when the reference is missing |
+| `empty`     | Optional | `ReactNode`         | -        | What to render when the field has no value or when the reference is missing |
 | `label`     | Optional | `string | Function` | `resources. [resource]. fields.[source]`   | Label to use for the field when rendered in layout components  |
 | `link`      | Optional | `string | Function` | `edit`   | Target of the link wrapping the rendered child. Set to `false` to disable the link. |
 | `queryOptions`     | Optional | [`UseQuery Options`](https://tanstack.com/query/v5/docs/react/reference/useQuery)                       | `{}`                             | `react-query` client options                                                                   |
 | `sortBy`    | Optional | `string | Function` | `source` | Name of the field to use for sorting when used in a Datagrid |
 
 `<ReferenceField>` also accepts the [common field props](./Fields.md#common-field-props).
 
-## `emptyText`
+## `empty`
 
-`<ReferenceField>` can display a custom message when the referenced record is missing, thanks to the `emptyText` prop.
+`<ReferenceField>` can display a custom message when the referenced record is missing, thanks to the `empty` prop.
 
 ```jsx
-<ReferenceField source="user_id" reference="users" emptyText="Missing user" />
+<ReferenceField source="user_id" reference="users" empty="Missing user" />
 ```
 
-`<ReferenceField>` renders the `emptyText`:
+`<ReferenceField>` renders the `empty` element when:
 
-- when the referenced record is missing (no record in the `users` table with the right `user_id`), or
-- when the field is empty (no `user_id` in the record).
+- the referenced record is missing (no record in the `users` table with the right `user_id`), or
+- the field is empty (no `user_id` in the record).
+
+When `empty` is a string, `<ReferenceField>` renders it as a `<Typography>` and passes the text through the i18n system, so you can use translation keys to have one message for each language supported by the interface:
+
+```jsx
+<ReferenceField source="user_id" reference="users" empty="resources.users.missing" />
+```
+
+You can also pass a React element to the `empty` prop:
+
+```jsx
+<ReferenceField source="user_id" reference="users" empty={<span>Missing user</span>} />
+```
 
 ## `label`
 

docs/ReferenceManyField.md

@@ -90,6 +90,7 @@ This example leverages [`<SingleFieldList>`](./SingleFieldList.md) to display an
 | -------------- | -------- | --------------------------------------------------------------------------------- | -------------------------------- | ----------------------------------------------------------------------------------- |
 | `children`     | Required | `Element`                                                                         | -                                | One or several elements that render a list of records based on a `ListContext`      |
 | `debounce`     | Optional | `number`                                                                          | 500                              | debounce time in ms for the `setFilters` callbacks                                  |
+| `empty`        | Optional | `ReactNode`                                                                       | -                                | Element to display when there are no related records.                                |
 | `filter`       | Optional | `Object`                                                                          | -                                | Filters to use when fetching the related records, passed to `getManyReference()`    |
 | `pagination`   | Optional | `Element`                                                                         | -                                | Pagination element to display pagination controls. empty by default (no pagination) |
 | `perPage`      | Optional | `number`                                                                          | 25                               | Maximum number of referenced records to fetch                                       |
@@ -176,6 +177,44 @@ const PostCommentsField = () => (
 );
 ```
 
+## `empty`
+
+Use `empty` to customize the text displayed when the related record is empty.
+
+```jsx
+<ReferenceManyField
+  reference="books"
+  target="author_id"
+  empty="no books"
+>
+    ...
+</ReferenceManyField>
+```
+
+`empty` also accepts a translation key.
+
+```jsx
+<ReferenceManyField
+  reference="books"
+  target="author_id"
+  empty="resources.authors.fields.books.empty"
+>
+    ...
+</ReferenceManyField>
+```
+
+`empty` also accepts a `ReactNode`.
+
+```jsx
+<ReferenceManyField
+  reference="books"
+  target="author_id"
+    empty={<CreateButton resource="books" />}
+>
+    ...
+</ReferenceManyField>
+```
+
 ## `filter`: Permanent Filter
 
 You can filter the query used to populate the possible values. Use the `filter` prop for that.

docs/ReferenceOneField.md

@@ -59,6 +59,7 @@ const BookShow = () => (
 | `reference`    | Required | `string`                                    | -                                | The name of the resource for the referenced records, e.g. 'book_details'            |
 | `target`       | Required | string                                      | -                                | Target field carrying the relationship on the referenced resource, e.g. 'book_id'   |
 | `children`     | Optional | `Element`                                   | -                                | The Field element used to render the referenced record                              |
+| `empty`        | Optional | `ReactNode`                         | -                                | The text or element to display when the referenced record is empty                   |
 | `filter`       | Optional | `Object`                                    | `{}`                             | Used to filter referenced records                                                   |
 | `link`         | Optional | `string | Function`                         | `edit`                           | Target of the link wrapping the rendered child. Set to `false` to disable the link. |
 | `queryOptions` | Optional | [`UseQueryOptions`](https://tanstack.com/query/v5/docs/react/reference/useQuery) | `{}` | `react-query` client options |
@@ -78,32 +79,32 @@ For instance, if you want to render both the genre and the ISBN for a book:
 </ReferenceOneField>
 ```
 
-## `emptyText`
+## `empty`
 
-Use `emptyText` to customize the text displayed when the related record is empty.
+Use `empty` to customize the text displayed when the related record is empty.
 
 ```jsx
-<ReferenceOneField label="Details" reference="book_details" target="book_id" emptyText="no detail">
+<ReferenceOneField label="Details" reference="book_details" target="book_id" empty="no detail">
     <TextField source="genre" /> (<TextField source="ISBN" />)
 </ReferenceOneField>
 ```
 
-`emptyText` also accepts a translation key.
+`empty` also accepts a translation key.
 
 ```jsx
-<ReferenceOneField label="Details" reference="book_details" target="book_id" emptyText="resources.books.not_found">
+<ReferenceOneField label="Details" reference="book_details" target="book_id" empty="resources.books.not_found">
     <TextField source="genre" /> (<TextField source="ISBN" />)
 </ReferenceOneField>
 ```
 
-`emptyText` also accepts a `ReactElement`.
+`empty` also accepts a `ReactNode`.
 
 ```jsx
 <ReferenceOneField
     label="Details"
     reference="book_details"
     target="book_id"
-    emptyText={<CreateButton to="/book_details/create" />}
+    empty={<CreateButton to="/book_details/create" />}
 >
     <TextField source="genre" /> (<TextField source="ISBN" />)
 </ReferenceOneField>

docs/WithRecord.md

@@ -23,7 +23,7 @@ const BookShow = () => (
 );
 ```
 
-Note that if `record` is undefined, `<WithRecord>` doesn't call the `render` callback and renders nothing, so you don't have to worry about this case in your render callback.
+Note that if `record` is undefined, `<WithRecord>` doesn't call the `render` callback and renders nothing (or the `empty` prop), so you don't have to worry about this case in your render callback.
 
 ## Availability
 

packages/ra-core/src/controller/field/ReferenceFieldBase.spec.tsx

@@ -8,12 +8,6 @@ import { ReferenceFieldBase } from './ReferenceFieldBase';
 import { Error, Loading, Meta } from './ReferenceFieldBase.stories';
 
 describe('<ReferenceFieldBase />', () => {
-    const defaultProps = {
-        reference: 'posts',
-        resource: 'comments',
-        source: 'post_id',
-    };
-
     beforeAll(() => {
         window.scrollTo = jest.fn();
     });
@@ -52,7 +46,7 @@ describe('<ReferenceFieldBase />', () => {
         });
         render(
             <CoreAdminContext dataProvider={dataProvider}>
-                <ReferenceFieldBase {...defaultProps}>
+                <ReferenceFieldBase reference="posts" source="post_id">
                     <MyComponent />
                 </ReferenceFieldBase>
             </CoreAdminContext>

packages/ra-core/src/controller/field/ReferenceFieldBase.tsx

@@ -6,6 +6,7 @@ import { RaRecord } from '../../types';
 import { useReferenceFieldController } from './useReferenceFieldController';
 import { ResourceContextProvider } from '../../core';
 import { RecordContextProvider } from '../record';
+import { useFieldValue } from '../../util';
 
 /**
  * Fetch reference record, and render its representation, or delegate rendering to child component.
@@ -43,11 +44,22 @@ export const ReferenceFieldBase = <
 >(
     props: ReferenceFieldBaseProps<ReferenceRecordType>
 ) => {
-    const { children } = props;
-
+    const { children, empty = null } = props;
+    const id = useFieldValue(props);
     const controllerProps =
         useReferenceFieldController<ReferenceRecordType>(props);
 
+    if (
+        (empty &&
+            // no foreign key value
+            !id) ||
+        // no reference record
+        (!controllerProps.error &&
+            !controllerProps.isPending &&
+            !controllerProps.referenceRecord)
+    ) {
+        return empty;
+    }
     return (
         <ResourceContextProvider value={props.reference}>
             <ReferenceFieldContextProvider value={controllerProps}>
@@ -64,6 +76,7 @@ export interface ReferenceFieldBaseProps<
 > {
     children?: ReactNode;
     className?: string;
+    empty?: ReactNode;
     error?: ReactNode;
     queryOptions?: Partial<
         UseQueryOptions<ReferenceRecordType[], Error> & {

packages/ra-core/src/controller/field/ReferenceManyFieldBase.tsx

@@ -0,0 +1,143 @@
+import React, { ReactNode } from 'react';
+import { ResourceContextProvider } from '../../core';
+import { ListContextProvider } from '../list/ListContextProvider';
+import {
+    useReferenceManyFieldController,
+    type UseReferenceManyFieldControllerParams,
+} from './useReferenceManyFieldController';
+import type { RaRecord } from '../../types';
+
+/**
+ * Render related records to the current one.
+ *
+ * You must define the fields to be passed to the iterator component as children.
+ *
+ * @example Display all the comments of the current post as a datagrid
+ * <ReferenceManyFieldBase reference="comments" target="post_id">
+ *     <Datagrid>
+ *         <TextField source="id" />
+ *         <TextField source="body" />
+ *         <DateField source="created_at" />
+ *         <EditButton />
+ *     </Datagrid>
+ * </ReferenceManyFieldBase>
+ *
+ * @example Display all the books by the current author, only the title
+ * <ReferenceManyFieldBase reference="books" target="author_id">
+ *     <SingleFieldList>
+ *         <ChipField source="title" />
+ *     </SingleFieldList>
+ * </ReferenceManyFieldBase>
+ *
+ * By default, restricts the displayed values to 25. You can extend this limit
+ * by setting the `perPage` prop.
+ *
+ * @example
+ * <ReferenceManyFieldBase perPage={10} reference="comments" target="post_id">
+ *    ...
+ * </ReferenceManyFieldBase>
+ *
+ * By default, orders the possible values by id desc. You can change this order
+ * by setting the `sort` prop (an object with `field` and `order` properties).
+ *
+ * @example
+ * <ReferenceManyFieldBase sort={{ field: 'created_at', order: 'DESC' }} reference="comments" target="post_id">
+ *    ...
+ * </ReferenceManyFieldBase>
+ *
+ * Also, you can filter the query used to populate the possible values. Use the
+ * `filter` prop for that.
+ *
+ * @example
+ * <ReferenceManyFieldBase filter={{ is_published: true }} reference="comments" target="post_id">
+ *    ...
+ * </ReferenceManyFieldBase>
+ */
+export const ReferenceManyFieldBase = <
+    RecordType extends RaRecord = RaRecord,
+    ReferenceRecordType extends RaRecord = RaRecord,
+>(
+    props: ReferenceManyFieldBaseProps<RecordType, ReferenceRecordType>
+) => {
+    const {
+        children,
+        debounce,
+        empty,
+        filter = defaultFilter,
+        page = 1,
+        pagination = null,
+        perPage = 25,
+        record,
+        reference,
+        resource,
+        sort = defaultSort,
+        source = 'id',
+        storeKey,
+        target,
+        queryOptions,
+    } = props;
+
+    const controllerProps = useReferenceManyFieldController<
+        RecordType,
+        ReferenceRecordType
+    >({
+        debounce,
+        filter,
+        page,
+        perPage,
+        record,
+        reference,
+        resource,
+        sort,
+        source,
+        storeKey,
+        target,
+        queryOptions,
+    });
+
+    if (
+        // there is an empty page component
+        empty &&
+        // there is no error
+        !controllerProps.error &&
+        // the list is not loading data for the first time
+        !controllerProps.isPending &&
+        // the API returned no data (using either normal or partial pagination)
+        (controllerProps.total === 0 ||
+            (controllerProps.total == null &&
+                // @ts-ignore FIXME total may be undefined when using partial pagination but the ListControllerResult type is wrong about it
+                controllerProps.hasPreviousPage === false &&
+                // @ts-ignore FIXME total may be undefined when using partial pagination but the ListControllerResult type is wrong about it
+                controllerProps.hasNextPage === false &&
+                // @ts-ignore FIXME total may be undefined when using partial pagination but the ListControllerResult type is wrong about it
+                controllerProps.data.length === 0)) &&
+        // the user didn't set any filters
+        !Object.keys(controllerProps.filterValues).length
+    ) {
+        return empty;
+    }
+
+    return (
+        <ResourceContextProvider value={reference}>
+            <ListContextProvider value={controllerProps}>
+                {children}
+                {pagination}
+            </ListContextProvider>
+        </ResourceContextProvider>
+    );
+};
+
+export interface ReferenceManyFieldBaseProps<
+    RecordType extends Record<string, any> = Record<string, any>,
+    ReferenceRecordType extends Record<string, any> = Record<string, any>,
+> extends UseReferenceManyFieldControllerParams<
+        RecordType,
+        ReferenceRecordType
+    > {
+    children: ReactNode;
+    empty?: ReactNode;
+    pagination?: ReactNode;
+}
+
+const defaultFilter = {};
+const defaultSort = { field: 'id', order: 'DESC' as const };