core[patch]: Add **kwargs to Langchain's dumps() to allow passing of json.dumps() … (#10628)

…parameters.

In Langchain's `dumps()` function, I've added a `**kwargs` parameter.
This allows users to pass additional parameters to the underlying
`json.dumps()` function, providing greater flexibility and control over
JSON serialization.

Many parameters available in `json.dumps()` can be useful or even
necessary in specific situations. For example, when using an Agent with
return_intermediate_steps set to true, the output is a list of
AgentAction objects. These objects can't be serialized without using
Langchain's `dumps()` function.

The issue arises when using the Agent with a language other than
English, which may contain non-ASCII characters like 'é'. The default
behavior of `json.dumps()` sets ensure_ascii to true, converting
`{"name": "José"}` into `{"name": "Jos\u00e9"}`. This can make the
output hard to read, especially in the case of intermediate steps in
agent logs.

By allowing users to pass additional parameters to `json.dumps()` via
Langchain's dumps(), we can solve this problem. For instance, users can
set `ensure_ascii=False` to maintain the original characters.

This update also enables users to pass other useful `json.dumps()`
parameters like `sort_keys`, providing even more flexibility.

The implementation takes into account edge cases where a user might pass
a "default" parameter, which is already defined by `dumps()`, or an
"indent" parameter, which is also predefined if `pretty=True` is set.

---------

Co-authored-by: Erick Friis <erick@langchain.dev>

libs/core/langchain_core/load/dump.py

@@ -13,12 +13,15 @@ def default(obj: Any) -> Any:
         return to_json_not_implemented(obj)
 
 
-def dumps(obj: Any, *, pretty: bool = False) -> str:
+def dumps(obj: Any, *, pretty: bool = False, **kwargs: Any) -> str:
     """Return a json string representation of an object."""
+    if "default" in kwargs:
+        raise ValueError("`default` should not be passed to dumps")
     if pretty:
-        return json.dumps(obj, default=default, indent=2)
+        indent = kwargs.pop("indent", 2)
+        return json.dumps(obj, default=default, indent=indent, **kwargs)
     else:
-        return json.dumps(obj, default=default)
+        return json.dumps(obj, default=default, **kwargs)
 
 
 def dumpd(obj: Any) -> Dict[str, Any]:

libs/langchain/tests/unit_tests/load/__snapshots__/test_dump.ambr

@@ -57,6 +57,9 @@
   }
   '''
 # ---
+# name: test_person_with_kwargs
+  '{"lc":1,"type":"constructor","id":["tests","unit_tests","load","test_dump","Person"],"kwargs":{"secret":{"lc":1,"type":"secret","id":["SECRET"]},"you_can_see_me":"hello"}}'
+# ---
 # name: test_serialize_llmchain
   '''
   {

libs/langchain/tests/unit_tests/load/test_dump.py

@@ -141,3 +141,14 @@ def test_serialize_llmchain_with_non_serializable_arg(snapshot: Any) -> None:
     prompt = PromptTemplate.from_template("hello {name}!")
     chain = LLMChain(llm=llm, prompt=prompt)
     assert dumps(chain, pretty=True) == snapshot
+
+
+def test_person_with_kwargs(snapshot: Any) -> None:
+    person = Person(secret="hello")
+    assert dumps(person, separators=(",", ":")) == snapshot
+
+
+def test_person_with_invalid_kwargs() -> None:
+    person = Person(secret="hello")
+    with pytest.raises(TypeError):
+        dumps(person, invalid_kwarg="hello")