Fix dict types not correctly forwarding previous nested values when parsing

CHANGELOG.rst

@@ -12,6 +12,15 @@ The semantic versioning only considers the public API as described in
 paths are considered internals and can change in minor and patch releases.
 
 
+v4.32.1 (2024-08-??)
+--------------------
+
+Fixed
+^^^^^
+- ``dict`` types not correctly forwarding previous nested values when parsing
+  (`#559 <https://github.com/omni-us/jsonargparse/pull/559>`__).
+
+
 v4.32.0 (2024-07-19)
 --------------------
 

jsonargparse/_typehints.py

@@ -904,7 +904,12 @@ def adapt_typehints(
                         for t in sub_add_kwargs["linked_targets"]
                     }
                 else:
-                    kwargs = adapt_kwargs
+                    kwargs = adapt_kwargs.copy()
+                if kwargs.get("prev_val"):
+                    if isinstance(kwargs["prev_val"], dict):
+                        kwargs["prev_val"] = kwargs["prev_val"].get(k)
+                    else:
+                        kwargs["prev_val"] = None
                 val[k] = adapt_typehints(v, subtypehints[1], **kwargs)
         if get_import_path(typehint.__class__) == "typing._TypedDictMeta":
             if typehint.__total__:

jsonargparse_tests/test_dataclass_like.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import dataclasses
+import json
 from typing import Any, Dict, Generic, List, Optional, Tuple, TypeVar, Union
 from unittest.mock import patch
 
@@ -684,6 +685,13 @@ class OptionalPydantic:
         def __init__(self, a: Optional[PydanticModel] = None):
             self.a = a
 
+    class NestedModel(pydantic.BaseModel):
+        inputs: List[str]
+        outputs: List[str]
+
+    class PydanticNestedDict(pydantic.BaseModel):
+        nested: Optional[Dict[str, NestedModel]] = None
+
 
 def none(x):
     return x
@@ -817,6 +825,23 @@ def test_optional_pydantic_model(self, parser):
         assert cfg.b.class_path == f"{__name__}.OptionalPydantic"
         assert cfg.b.init_args == Namespace(a=Namespace(p1="x", p2=3))
 
+    def test_nested_dict(self, parser):
+        parser.add_argument("--config", action="config")
+        parser.add_argument("--model", type=PydanticNestedDict)
+        model = {
+            "nested": {
+                "key": {
+                    "inputs": ["a", "b"],
+                    "outputs": ["x", "y"],
+                }
+            }
+        }
+        cfg = parser.parse_args(["--model", json.dumps(model)])
+        assert cfg.model.nested["key"] == Namespace(inputs=["a", "b"], outputs=["x", "y"])
+        init = parser.instantiate_classes(cfg)
+        assert isinstance(init.model, PydanticNestedDict)
+        assert isinstance(init.model.nested["key"], NestedModel)
+
 
 # attrs tests