Extraction Chain - Custom Prompt (#9828)

# Description

This change allows you to customize the prompt used in
`create_extraction_chain` as well as `create_extraction_chain_pydantic`.

It also adds the `verbose` argument to
`create_extraction_chain_pydantic` - because `create_extraction_chain`
had it already and `create_extraction_chain_pydantic` did not.

# Issue
N/A

# Dependencies
N/A

# Twitter
https://twitter.com/CamAHutchison

libs/langchain/langchain/chains/openai_functions/extraction.py

@@ -1,4 +1,4 @@
-from typing import Any, List
+from typing import Any, List, Optional
 
 from langchain.chains.base import Chain
 from langchain.chains.llm import LLMChain
@@ -13,6 +13,7 @@ from langchain.output_parsers.openai_functions import (
 )
 from langchain.prompts import ChatPromptTemplate
 from langchain.pydantic_v1 import BaseModel
+from langchain.schema import BasePromptTemplate
 from langchain.schema.language_model import BaseLanguageModel
 
 
@@ -43,13 +44,17 @@ Passage:
 
 
 def create_extraction_chain(
-    schema: dict, llm: BaseLanguageModel, verbose: bool = False
+    schema: dict,
+    llm: BaseLanguageModel,
+    prompt: Optional[BasePromptTemplate] = None,
+    verbose: bool = False,
 ) -> Chain:
     """Creates a chain that extracts information from a passage.
 
     Args:
         schema: The schema of the entities to extract.
         llm: The language model to use.
+        prompt: The prompt to use for extraction.
         verbose: Whether to run in verbose mode. In verbose mode, some intermediate
             logs will be printed to the console. Defaults to `langchain.verbose` value.
 
@@ -57,12 +62,12 @@ def create_extraction_chain(
         Chain that can be used to extract information from a passage.
     """
     function = _get_extraction_function(schema)
-    prompt = ChatPromptTemplate.from_template(_EXTRACTION_TEMPLATE)
+    extraction_prompt = prompt or ChatPromptTemplate.from_template(_EXTRACTION_TEMPLATE)
     output_parser = JsonKeyOutputFunctionsParser(key_name="info")
     llm_kwargs = get_llm_kwargs(function)
     chain = LLMChain(
         llm=llm,
-        prompt=prompt,
+        prompt=extraction_prompt,
         llm_kwargs=llm_kwargs,
         output_parser=output_parser,
         verbose=verbose,
@@ -71,13 +76,19 @@ def create_extraction_chain(
 
 
 def create_extraction_chain_pydantic(
-    pydantic_schema: Any, llm: BaseLanguageModel
+    pydantic_schema: Any,
+    llm: BaseLanguageModel,
+    prompt: Optional[BasePromptTemplate] = None,
+    verbose: bool = False,
 ) -> Chain:
     """Creates a chain that extracts information from a passage using pydantic schema.
 
     Args:
         pydantic_schema: The pydantic schema of the entities to extract.
         llm: The language model to use.
+        prompt: The prompt to use for extraction.
+        verbose: Whether to run in verbose mode. In verbose mode, some intermediate
+            logs will be printed to the console. Defaults to `langchain.verbose` value.
 
     Returns:
         Chain that can be used to extract information from a passage.
@@ -92,15 +103,16 @@ def create_extraction_chain_pydantic(
     )
 
     function = _get_extraction_function(openai_schema)
-    prompt = ChatPromptTemplate.from_template(_EXTRACTION_TEMPLATE)
+    extraction_prompt = prompt or ChatPromptTemplate.from_template(_EXTRACTION_TEMPLATE)
     output_parser = PydanticAttrOutputFunctionsParser(
         pydantic_schema=PydanticSchema, attr_name="info"
     )
     llm_kwargs = get_llm_kwargs(function)
     chain = LLMChain(
         llm=llm,
-        prompt=prompt,
+        prompt=extraction_prompt,
         llm_kwargs=llm_kwargs,
         output_parser=output_parser,
+        verbose=verbose,
     )
     return chain