added finish reason exception IncompleteOutputException (#279)

instructor/exceptions.py

@@ -0,0 +1,6 @@
+class IncompleteOutputException(Exception):
+    """Exception raised when the output from LLM is incomplete due to max tokens limit reached."""
+
+    def __init__(self, message="The output is incomplete due to a max_tokens length limit."):
+        self.message = message
+        super().__init__(self.message)

instructor/function_calls.py

@@ -1,6 +1,7 @@
 from docstring_parser import parse
 from functools import wraps
 from pydantic import BaseModel, create_model
+from instructor.exceptions import IncompleteOutputException
 
 import enum
 
@@ -121,6 +122,9 @@ class OpenAISchema(BaseModel):
         Returns:
             cls (OpenAISchema): An instance of the class
         """
+        if completion.choices[0].finish_reason == 'length':
+            raise IncompleteOutputException()
+      
         if stream_multitask:
             return cls.from_streaming_response(completion, mode)
 
@@ -179,6 +183,9 @@ class OpenAISchema(BaseModel):
         Returns:
             cls (OpenAISchema): An instance of the class
         """
+        if completion.choices[0].finish_reason == 'length':
+            raise IncompleteOutputException()
+        
         if stream_multitask:
             return await cls.from_streaming_response_async(completion, mode)
 
@@ -225,4 +232,4 @@ def openai_schema(cls) -> OpenAISchema:
             cls.__name__,
             __base__=(cls, OpenAISchema),
         )
-    )  # type: ignore
+    )  # type: ignore