try to address #1876 and use also defaultValue via tOptions as fallback

Author: adrai

CHANGELOG.md

@@ -1,3 +1,8 @@
+### 16.1.5
+
+- fix: Incosistent behaviour of Trans and t. Trans set defaultValue when t call doesn't set the field. [1876](https://github.com/i18next/react-i18next/issues/1876)
+- Trans: use also defaultValue via tOptions as fallback
+
 ### 16.1.4
 
 - fix: detect pre-transformation use of interpolation like number/date/etc. [1875](https://github.com/i18next/react-i18next/pull/1875)

react-i18next.js

@@ -2690,7 +2690,7 @@
     let namespaces = ns || t.ns || i18n.options?.defaultNS;
     namespaces = isString(namespaces) ? [namespaces] : namespaces || ['translation'];
     const nodeAsString = nodesToString(children, reactI18nextOptions, i18n, i18nKey);
-    const defaultValue = defaults || nodeAsString || reactI18nextOptions.transEmptyNodeValue || (typeof i18nKey === 'function' ? keysFromSelector(i18nKey) : i18nKey);
+    const defaultValue = defaults || tOptions?.defaultValue || nodeAsString || reactI18nextOptions.transEmptyNodeValue || (typeof i18nKey === 'function' ? keysFromSelector(i18nKey) : i18nKey);
     const {
       hashTransKey
     } = reactI18nextOptions;
@@ -2716,7 +2716,7 @@
       count,
       ...values,
       ...interpolationOverride,
-      defaultValue,
+      defaultValue: defaults || tOptions?.defaultValue,
       ns: namespaces
     };
     const translation = key ? t(key, combinedTOpts) : defaultValue;

react-i18next.min.js

@@ -426,6 +426,7 @@ export function Trans({
   const nodeAsString = nodesToString(children, reactI18nextOptions, i18n, i18nKey);
   const defaultValue =
     defaults ||
+    tOptions?.defaultValue ||
     nodeAsString ||
     reactI18nextOptions.transEmptyNodeValue ||
     (typeof i18nKey === 'function' ? keyFromSelector(i18nKey) : i18nKey);
@@ -452,7 +453,7 @@ export function Trans({
     count,
     ...values,
     ...interpolationOverride,
-    defaultValue,
+    defaultValue: defaults || tOptions?.defaultValue,
     ns: namespaces,
   };
   const translation = key ? t(key, combinedTOpts) : defaultValue;

src/TransWithoutContext.js

@@ -1082,6 +1082,42 @@ describe('trans with defaults property and children', () => {
   });
 });
 
+describe('trans with defaults property and no children', () => {
+  function TestComponent() {
+    return <Trans i18nKey="missing-key-here" count={2} defaults="There are {{ count }} items" />;
+  }
+
+  it('should render correct content', () => {
+    const { container } = render(<TestComponent />);
+    expect(container.firstChild).toMatchInlineSnapshot(`
+      <div>
+        There are 2 items
+      </div>
+    `);
+  });
+});
+
+describe('trans with defaults (via tOptions) property and no children', () => {
+  function TestComponent() {
+    return (
+      <Trans
+        i18nKey="missing-key-here"
+        count={4}
+        tOptions={{ defaultValue: 'There are {{ count }} items' }}
+      />
+    );
+  }
+
+  it('should render correct content', () => {
+    const { container } = render(<TestComponent />);
+    expect(container.firstChild).toMatchInlineSnapshot(`
+      <div>
+        There are 4 items
+      </div>
+    `);
+  });
+});
+
 describe('trans with nesting $t()', () => {
   function TestComponent({ parent }) {
     return <Trans i18nKey="nestingKey1" ns="other" parent={parent} />;