Fix nested type imports in x-python-type override (#2842)

* Fix nested type imports in x-python-type override

* Add test for nested unknown type to cover partial branch

Author: koxudaxi

src/datamodel_code_generator/parser/jsonschema.py

@@ -8,6 +8,7 @@
 
 import enum as _enum
 import json
+import re
 from collections import defaultdict
 from collections.abc import Iterable
 from contextlib import contextmanager, suppress
@@ -1334,6 +1335,13 @@ def _is_compatible_python_type(self, schema_type: str | None, python_type: str)
         compatible = self.COMPATIBLE_PYTHON_TYPES.get(schema_type, frozenset())
         return base_type in compatible
 
+    def _extract_all_type_names(self, type_str: str) -> list[str]:  # noqa: PLR6301
+        """Extract all type names from a type annotation string."""
+        # Match type names: word characters starting with uppercase, not preceded by a dot
+        # This handles cases like Callable[[Iterable[str]], str]
+        pattern = r"(?<![.\w])([A-Z]\w*)"
+        return re.findall(pattern, type_str)
+
     def _get_python_type_override(self, obj: JsonSchemaObject) -> DataType | None:
         """Get DataType from x-python-type if it's incompatible with schema type."""
         x_python_type = obj.extras.get("x-python-type")
@@ -1357,7 +1365,18 @@ def _get_python_type_override(self, obj: JsonSchemaObject) -> DataType | None:
                 # If not in predefined imports, create import from the full path
                 import_ = Import.from_full_path(prefix)
 
-        return self.data_type(type=type_str, import_=import_)
+        # Collect imports for all nested types (e.g., Iterable inside Callable[[Iterable[str]], str])
+        nested_imports: list[DataType] = []
+        for type_name in self._extract_all_type_names(type_str):
+            if type_name != base_type:
+                nested_import = self.PYTHON_TYPE_IMPORTS.get(type_name)
+                if nested_import:
+                    nested_imports.append(self.data_type(import_=nested_import))
+
+        result = self.data_type(type=type_str, import_=import_)
+        if nested_imports:
+            result.data_types.extend(nested_imports)
+        return result
 
     def _apply_title_as_name(self, name: str, obj: JsonSchemaObject) -> str:
         """Apply title as name if use_title_as_name is enabled."""

tests/data/expected/main/jsonschema/x_python_type_nested_imports.py

@@ -0,0 +1,14 @@
+# generated by datamodel-codegen:
+#   filename:  x_python_type_nested_imports.json
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from collections.abc import Callable, Iterable
+from typing import TypedDict
+
+from typing_extensions import NotRequired
+
+
+class Model(TypedDict):
+    callback: NotRequired[Callable[[Iterable[str]], str]]

tests/data/expected/main/jsonschema/x_python_type_nested_unknown_type.py

@@ -0,0 +1,14 @@
+# generated by datamodel-codegen:
+#   filename:  x_python_type_nested_unknown_type.json
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from collections.abc import Callable
+from typing import TypedDict
+
+from typing_extensions import NotRequired
+
+
+class Model(TypedDict):
+    callback: NotRequired[Callable[[MyCustomType[str]], str]]

tests/data/jsonschema/x_python_type_nested_imports.json

@@ -0,0 +1,9 @@
+{
+  "type": "object",
+  "properties": {
+    "callback": {
+      "type": "string",
+      "x-python-type": "Callable[[Iterable[str]], str]"
+    }
+  }
+}

tests/data/jsonschema/x_python_type_nested_unknown_type.json

@@ -0,0 +1,9 @@
+{
+  "type": "object",
+  "properties": {
+    "callback": {
+      "type": "string",
+      "x-python-type": "Callable[[MyCustomType[str]], str]"
+    }
+  }
+}

tests/main/jsonschema/test_main_jsonschema.py

@@ -7031,3 +7031,25 @@ def test_x_python_type_custom_fqpath(output_file: Path) -> None:
         assert_func=assert_file_content,
         extra_args=["--output-model-type", "typing.TypedDict"],
     )
+
+
+def test_x_python_type_nested_imports(output_file: Path) -> None:
+    """Test x-python-type with nested types that require imports (e.g., Callable[[Iterable[str]], str])."""
+    run_main_and_assert(
+        input_path=JSON_SCHEMA_DATA_PATH / "x_python_type_nested_imports.json",
+        output_path=output_file,
+        input_file_type=None,
+        assert_func=assert_file_content,
+        extra_args=["--output-model-type", "typing.TypedDict"],
+    )
+
+
+def test_x_python_type_nested_unknown_type(output_file: Path) -> None:
+    """Test x-python-type with nested types not in PYTHON_TYPE_IMPORTS (e.g., MyCustomType)."""
+    run_main_and_assert(
+        input_path=JSON_SCHEMA_DATA_PATH / "x_python_type_nested_unknown_type.json",
+        output_path=output_file,
+        input_file_type=None,
+        assert_func=assert_file_content,
+        extra_args=["--output-model-type", "typing.TypedDict"],
+    )