Allow defining translatable_fields/override_translatable_fields on StructBlock

wagtail_localize/segments/extract.py

@@ -123,7 +123,17 @@ def handle_related_object_block(self, related_object):
     def handle_struct_block(self, struct_block, raw_value=None):
         segments = []
 
+        override_translatable_blocks = getattr(
+            struct_block.block, "override_translatable_blocks", None
+        )
+
         for field_name, block_value in struct_block.items():
+            if (
+                override_translatable_blocks is not None
+                and field_name not in override_translatable_blocks
+            ):
+                continue
+
             block_type = struct_block.block.child_blocks[field_name]
             try:
                 block_raw_value = raw_value["value"].get(field_name)

wagtail_localize/segments/tests/test_segment_extraction.py

@@ -533,6 +533,40 @@ def test_customstructblock(self):
             ],
         )
 
+    def test_structblockwithoverrides(self):
+        block_id = uuid.uuid4()
+        page = make_test_page_with_streamfield_block(
+            str(block_id),
+            "test_structblockwithoverrides",
+            {"field_a": "Test content", "field_b": "Non-translatable content"},
+        )
+
+        segments = extract_segments(page)
+
+        self.assertEqual(
+            segments,
+            [
+                StringSegmentValue(
+                    f"test_streamfield.{block_id}.field_a",
+                    "Test content",
+                )
+            ],
+        )
+
+    def test_structblockignoreall(self):
+        block_id = uuid.uuid4()
+        page = make_test_page_with_streamfield_block(
+            str(block_id),
+            "test_structblockignoreall",
+            {
+                "field_a": "Non-translatable content",
+                "field_b": "Non-translatable content",
+            },
+        )
+
+        segments = extract_segments(page)
+        self.assertEqual(segments, [])
+
     def test_customblockwithoutextractmethod(self):
         block_id = uuid.uuid4()
         page = make_test_page_with_streamfield_block(

wagtail_localize/test/models.py

@@ -119,6 +119,20 @@ class TestNestedStreamBlock(blocks.StreamBlock):
     chooser_in_list = blocks.ListBlock(blocks.PageChooserBlock())
 
 
+class TestStructBlockOverride(blocks.StructBlock):
+    field_a = blocks.TextBlock()
+    field_b = blocks.TextBlock()
+
+    override_translatable_blocks = ["field_a"]
+
+
+class TestStructBlockIgnoreAll(blocks.StructBlock):
+    field_a = blocks.TextBlock()
+    field_b = blocks.TextBlock()
+
+    override_translatable_blocks = []
+
+
 class TestNestedChooserStructBlock(blocks.StructBlock):
     nested_page = TestChooserStructBlock()
 
@@ -196,6 +210,8 @@ class TestStreamBlock(blocks.StreamBlock):
     test_nestedstreamblock = TestNestedStreamBlock()
     test_streamblock_in_structblock = TestStreamBlockInStructBlock()
     test_customstructblock = CustomStructBlock()
+    test_structblockwithoverrides = TestStructBlockOverride()
+    test_structblockignoreall = TestStructBlockIgnoreAll()
     test_customblockwithoutextractmethod = CustomBlockWithoutExtractMethod()
     test_pagechooserblock = blocks.PageChooserBlock()
     test_pagechooserblock_with_restricted_types = blocks.PageChooserBlock(