solved issue that adaptation crashes when havig multiple nested promp… (#1181)

I have faced the issue that when I adapt some prompts, some of the
key-value pairs are objects itself and then do not get stored properly.
The adaptation does not fail, however, when loading those prompt, they
break since they are not in proper json format. This fix solves this
particular issue I am using json.dumps on those object to store
json-conform strings.

Co-authored-by: Sergiu Soima <[email protected]>

Author: ssoima

src/ragas/llms/prompt.py

@@ -158,6 +158,10 @@ def format(self, **kwargs: t.Any) -> PromptValue:
             raise ValueError(
                 f"Input variables {self.input_keys} do not match with the given parameters {list(kwargs.keys())}"
             )
+        for key, value in kwargs.items():
+            if isinstance(value, str):
+                kwargs[key] = json.dumps(value)
+
         prompt = self.to_string()
         return PromptValue(prompt_str=prompt.format(**kwargs))