feat: make Translate children optional (#5683)

Co-authored-by: slorber <lorber.sebastien@gmail.com>

packages/docusaurus-module-type-aliases/src/index.d.ts

@@ -141,16 +141,16 @@ declare module '@docusaurus/Interpolate' {
 }
 
 declare module '@docusaurus/Translate' {
-  import type {
+  import type {ReactNode} from 'react';
-    InterpolateProps,
+  import type {InterpolateValues} from '@docusaurus/Interpolate';
-    InterpolateValues,
-  } from '@docusaurus/Interpolate';
 
-  export type TranslateParam<Str extends string> = Partial<
+  // TS type to ensure that at least one of id or message is always provided
-    InterpolateProps<Str>
+  // (Generic permits to handled message provided as React children)
-  > & {
+  type IdOrMessage<MessageKey extends 'children' | 'message'> =
-    message: Str;
+    | ({[key in MessageKey]: string} & {id?: string})
-    id?: string;
+    | ({[key in MessageKey]?: string} & {id: string});
+
+  export type TranslateParam<Str extends string> = IdOrMessage<'message'> & {
     description?: string;
     values?: InterpolateValues<Str, string | number>;
   };
@@ -160,9 +160,9 @@ declare module '@docusaurus/Translate' {
     values?: InterpolateValues<Str, string | number>,
   ): string;
 
-  export type TranslateProps<Str extends string> = InterpolateProps<Str> & {
+  export type TranslateProps<Str extends string> = IdOrMessage<'children'> & {
-    id?: string;
     description?: string;
+    values?: InterpolateValues<Str, ReactNode>;
   };
 
   export default function Translate<Str extends string>(

packages/docusaurus/src/client/exports/Translate.tsx

@@ -5,11 +5,8 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import React from 'react';
+import {ReactNode} from 'react';
-import Interpolate, {
+import {interpolate, InterpolateValues} from '@docusaurus/Interpolate';
-  interpolate,
-  InterpolateValues,
-} from '@docusaurus/Interpolate';
 import type {TranslateParam, TranslateProps} from '@docusaurus/Translate';
 
 // Can't read it from context, due to exposing imperative API
@@ -19,10 +16,16 @@ function getLocalizedMessage({
   id,
   message,
 }: {
-  message: string;
+  message?: string;
   id?: string;
 }): string {
-  return codeTranslations[id ?? message] ?? message;
+  if (typeof id === 'undefined' && typeof message === 'undefined') {
+    throw new Error(
+      'Docusaurus translation declarations must have at least a translation id or a default translation message',
+    );
+  }
+
+  return codeTranslations[(id ?? message)!] ?? message ?? id;
 }
 
 // Imperative translation API is useful for some edge-cases:
@@ -32,7 +35,7 @@ export function translate<Str extends string>(
   {message, id}: TranslateParam<Str>,
   values?: InterpolateValues<Str, string | number>,
 ): string {
-  const localizedMessage = getLocalizedMessage({message, id}) ?? message;
+  const localizedMessage = getLocalizedMessage({message, id});
   return interpolate(localizedMessage, values);
 }
 
@@ -42,16 +45,14 @@ export default function Translate<Str extends string>({
   children,
   id,
   values,
-}: TranslateProps<Str>): JSX.Element {
+}: TranslateProps<Str>): ReactNode {
-  if (typeof children !== 'string') {
+  if (children && typeof children !== 'string') {
     console.warn('Illegal <Translate> children', children);
     throw new Error(
       'The Docusaurus <Translate> component only accept simple string values',
     );
   }
 
-  const localizedMessage: string =
+  const localizedMessage: string = getLocalizedMessage({message: children, id});
-    getLocalizedMessage({message: children, id}) ?? children;
+  return interpolate(localizedMessage, values);
-
-  return <Interpolate values={values}>{localizedMessage}</Interpolate>;
 }

packages/docusaurus/src/client/exports/__tests__/Translate.test.tsx

@@ -0,0 +1,31 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {translate} from '../Translate';
+
+describe('translate', () => {
+  test('accept id and use it as fallback', () => {
+    expect(translate({id: 'some-id'})).toEqual('some-id');
+  });
+
+  test('accept message and use it as fallback', () => {
+    expect(translate({message: 'some-message'})).toEqual('some-message');
+  });
+
+  test('accept id+message and use message as fallback', () => {
+    expect(translate({id: 'some-id', message: 'some-message'})).toEqual(
+      'some-message',
+    );
+  });
+
+  test('reject when no id or message', () => {
+    // @ts-expect-error: TS should protect when both id/message are missing
+    expect(() => translate({})).toThrowErrorMatchingInlineSnapshot(
+      `"Docusaurus translation declarations must have at least a translation id or a default translation message"`,
+    );
+  });
+});

packages/docusaurus/src/server/translations/__tests__/translationsExtractor.test.ts

@@ -84,7 +84,7 @@ const unrelated =  42;
     });
   });
 
-  test('extract from a translate() function call', async () => {
+  test('extract from a translate() functions calls', async () => {
     const {sourceCodeFilePath} = await createTmpSourceCodeFile({
       extension: 'js',
       content: `
@@ -92,6 +92,8 @@ export default function MyComponent() {
   return (
     <div>
       <input text={translate({id: 'codeId',message: 'code message',description: 'code description'})}/>
+
+      <input text={translate({id: 'codeId1'})}/>
     </div>
   );
 }
@@ -107,12 +109,13 @@ export default function MyComponent() {
       sourceCodeFilePath,
       translations: {
         codeId: {message: 'code message', description: 'code description'},
+        codeId1: {message: 'codeId1'},
       },
       warnings: [],
     });
   });
 
-  test('extract from a <Translate> component', async () => {
+  test('extract from a <Translate> components', async () => {
     const {sourceCodeFilePath} = await createTmpSourceCodeFile({
       extension: 'js',
       content: `
@@ -122,6 +125,8 @@ export default function MyComponent() {
       <Translate id="codeId" description={"code description"}>
         code message
       </Translate>
+
+      <Translate id="codeId1" />
     </div>
   );
 }
@@ -137,6 +142,7 @@ export default function MyComponent() {
       sourceCodeFilePath,
       translations: {
         codeId: {message: 'code message', description: 'code description'},
+        codeId1: {message: 'codeId1'},
       },
       warnings: [],
     });

packages/docusaurus/src/server/translations/translationsExtractor.ts

@@ -177,14 +177,10 @@ function extractSourceCodeAstTranslations(
   ast: Node,
   sourceCodeFilePath: string,
 ): SourceCodeFileTranslations {
-  function staticTranslateJSXWarningPart() {
+  function sourceWarningPart(node: Node) {
-    return 'Translate content could not be extracted.\nIt has to be a static string and use optional but static props, like <Translate id="my-id" description="my-description">text</Translate>.';
+    return `File: ${sourceCodeFilePath} at ${
-  }
+      node.loc?.start.line
-  function sourceFileWarningPart(node: Node) {
+    } line\nFull code: ${generate(node).code}`;
-    return `File=${sourceCodeFilePath} at line=${node.loc?.start.line}`;
-  }
-  function generateCode(node: Node) {
-    return generate(node).code;
   }
 
   const translations: Record<string, TranslationMessage> = {};
@@ -228,9 +224,9 @@ function extractSourceCodeAstTranslations(
             return attributeValueEvaluated.value;
           } else {
             warnings.push(
-              `<Translate> prop=${propName} should be a statically evaluable object.\nExample: <Translate id="optional.id" description="optional description">Message</Translate>\nDynamically constructed values are not allowed, because they prevent translations to be extracted.\n${sourceFileWarningPart(
+              `<Translate> prop=${propName} should be a statically evaluable object.\nExample: <Translate id="optional.id" description="optional description">Message</Translate>\nDynamically constructed values are not allowed, because they prevent translations to be extracted.\n${sourceWarningPart(
                 path.node,
-              )}\n${generateCode(path.node)}`,
+              )}`,
             );
           }
         }
@@ -238,41 +234,51 @@ function extractSourceCodeAstTranslations(
         return undefined;
       }
 
-      // We only handle the optimistic case where we have a single non-empty content
+      const id = evaluateJSXProp('id');
-      const singleChildren = path
+      const description = evaluateJSXProp('description');
-        .get('children')
+      let message;
+      const childrenPath = path.get('children');
+
+      // Handle empty content
+      if (!childrenPath.length) {
+        if (!id) {
+          warnings.push(`
+            <Translate> without children must have id prop.\nExample: <Translate id="my-id" />\n${sourceWarningPart(
+              path.node,
+            )}
+          `);
+        } else {
+          translations[id] = {
+            message: message ?? id,
+            ...(description && {description}),
+          };
+        }
+
+        return;
+      }
+
+      // Handle single non-empty content
+      const singleChildren = childrenPath
         // Remove empty/useless text nodes that might be around our translation!
         // Makes the translation system more reliable to JSX formatting issues
         .filter(
-          (childrenPath) =>
+          (children) =>
             !(
-              childrenPath.isJSXText() &&
+              children.isJSXText() &&
-              childrenPath.node.value.replace('\n', '').trim() === ''
+              children.node.value.replace('\n', '').trim() === ''
             ),
         )
         .pop();
-
+      const isJSXText = singleChildren && singleChildren.isJSXText();
-      if (singleChildren && singleChildren.isJSXText()) {
+      const isJSXExpressionContainer =
-        const message = singleChildren.node.value.trim().replace(/\s+/g, ' ');
-
-        const id = evaluateJSXProp('id');
-        const description = evaluateJSXProp('description');
-
-        translations[id ?? message] = {
-          message,
-          ...(description && {description}),
-        };
-      } else if (
         singleChildren &&
         singleChildren.isJSXExpressionContainer() &&
-        (singleChildren.get('expression') as NodePath).evaluate().confident
+        (singleChildren.get('expression') as NodePath).evaluate().confident;
-      ) {
-        const message = (
-          singleChildren.get('expression') as NodePath
-        ).evaluate().value;
 
-        const id = evaluateJSXProp('id');
+      if (isJSXText || isJSXExpressionContainer) {
-        const description = evaluateJSXProp('description');
+        message = isJSXText
+          ? singleChildren.node.value.trim().replace(/\s+/g, ' ')
+          : (singleChildren.get('expression') as NodePath).evaluate().value;
 
         translations[id ?? message] = {
           message,
@@ -280,9 +286,9 @@ function extractSourceCodeAstTranslations(
         };
       } else {
         warnings.push(
-          `${staticTranslateJSXWarningPart()}\n${sourceFileWarningPart(
+          `Translate content could not be extracted. It has to be a static string and use optional but static props, like <Translate id="my-id" description="my-description">text</Translate>.\n${sourceWarningPart(
             path.node,
-          )}\n${generateCode(path.node)}`,
+          )}`,
         );
       }
     },
@@ -308,21 +314,21 @@ function extractSourceCodeAstTranslations(
         ) {
           const {message, id, description} = firstArgEvaluated.value;
           translations[id ?? message] = {
-            message,
+            message: message ?? id,
             ...(description && {description}),
           };
         } else {
           warnings.push(
-            `translate() first arg should be a statically evaluable object.\nExample: translate({message: "text",id: "optional.id",description: "optional description"}\nDynamically constructed values are not allowed, because they prevent translations to be extracted.\n${sourceFileWarningPart(
+            `translate() first arg should be a statically evaluable object.\nExample: translate({message: "text",id: "optional.id",description: "optional description"}\nDynamically constructed values are not allowed, because they prevent translations to be extracted.\n${sourceWarningPart(
               path.node,
-            )}\n${generateCode(path.node)}`,
+            )}`,
           );
         }
       } else {
         warnings.push(
-          `translate() function only takes 1 or 2 args\n${sourceFileWarningPart(
+          `translate() function only takes 1 or 2 args\n${sourceWarningPart(
             path.node,
-          )}\n${generateCode(path.node)}`,
+          )}`,
         );
       }
     },

website/docs/docusaurus-core.md

@@ -253,6 +253,16 @@ export default function Home() {
 }
 ```
 
+:::note
+
+You can even omit a children prop and specify a translation string in your `code.json` file manually after running the `docusaurus write-translations` CLI command.
+
+```jsx
+<Translate id="homepage.title" />
+```
+
+:::
+
 ## Hooks {#hooks}
 
 ### `useDocusaurusContext` {#usedocusauruscontext}