I have invoice’s raw texts, I’m trying to create a desired json object using the that raw texts using any open source models or paid one.
I’m stuck where I have prompt but I don’t know which langchain’s chain should I use for this task.

from langchain.chains import StuffDocumentsChain, LLMChain
from langchain_core.prompts import PromptTemplate
from langchain_core.example_selectors import SemanticSimilarityExampleSelector
from langchain_community.llms import OpenAI
from langchain_community.vectorstores import Chroma
from langchain.prompts import FewShotPromptTemplate


def json_formatter(texts: str):
    llm = OpenAI()
    embeddings = HuggingFaceEmbeddings(
        model_name="sentence-transformers/all-MiniLM-L6-v2"
    )
    to_vectorize = [" ".join(example.values()) for example in few_shots]
    
    vectorstore = Chroma.from_texts(to_vectorize, embeddings, metadatas=few_shots)

    example_selector = SemanticSimilarityExampleSelector(
        vectorstore=vectorstore,
        k=2)

    example_prompt = PromptTemplate(
        input_variables=["raw_texts", "json_structure"],
        template="\raw_texts: {raw_texts}njson_structure: {json_structure}",
    )

    few_shot_prompt = FewShotPromptTemplate(
        example_selector=example_selector,
        example_prompt=example_prompt,
        suffix=PROMPT_SUFFIX,
        input_variables=["raw_texts", "json_structure"],  # These variables are used in the prefix and suffix
    )
    llm_chain = LLMChain(llm=llm, prompt=prompt)
    chain = StuffDocumentsChain(
                   llm_chain=llm_chain,
                   document_prompt=few_shot_prompt 
)

here StuffDocumentsChain is just an example I don’t know which chain should I use for this task.

my json_format is like below

structure = """{
    "invoice":{
        "invoice_number":"",
        "invoice_date":"",
        "irn":"",
        "acknowledgement":{
            "ack_number":"",
            "ack_date":""
        },
        "customer_details":{
            "name":"",
            "contact":"",
            "address":"",
            "gstin":"",
            "pan":"",
            "state":"",
            "state_code":""
        },
        "order_details":{
            "order_number":"",
            "order_date":""
        },
        "delivery_agent":{
            "name":""
        },
        "payment_terms":"",
        "place_of_supply":"",
        "items":[
            {
                "description":"",
                "hsn/sac":"",
                "quantity":"",
                "rate_per_unit(inclusive_of_tax)":"",
                "rate_per_unit(exclusive_of_tax)":"",
                "amount":""
            }
        ],
        "taxes":{
            "igst_rate":"",
            "igst_amount":"",
            "cgst_rate":"",
            "cgst_amount":"",
            "sgst_rate/utgst_rate":"",
            "sgst_amount/utgst_amount":"",
            "total_tax":""
        },
        "total_amount":"",
        "amount_in_words":"",
        "discount_in_%":"",
        "discount_in_amount":"",
        "supplier_details":{
            "gstin":"",
            "pan":"",
            "bank_details":{
                "branch":"",
                "ifsc_code":""
            }
        },
        "beneficiary_name":"",
        "bank_name":"",
        "Bank_account_number":"",
        "swift_code":"",
        "terms_conditions":""
    }
}

and the example raw tests are like

raw_text = """ 
              vil Original C) Duplicate C) Triplicate
                    TAX INVOICE
                    
                    O PTOTEC H GSTIN: 29JS757SE1ZC
                    
                    State: 29 - Karnataka
                    
                    NO R8 SHOPE NO 02 TUBINAKERE
                    
                    A.) 7892088815 &3 _ [email protected] [°] VILLAGE AND POST KOTHATHI HOBLI
                    MANDYA TALUK MANDYA DIST
                    Invoice No.: 110 Bill To:
                    Place of Supply: 37-Andhra Pradesh Lotus Wireless
                    — —— Technologies india
                    PO date: 27/09/2022
                    PO number: wr/po/22-23/0608 +©~CséP Vt. td B-7,B Block,
                    Industrial
                    Park, Autonagar
                    Visakhapatnam,Andra
                    Pradesh,INDIA Pin-
                    530012
                    
                    Lotus Wireless Technologies india pvt.ltd B-7,B
                    Block, Industrial Park,Autonagar
                    Visakhapatnam,Andra Pradesh,INDIA Pin-530012
                    
                    Contact No.: 00918912761678
                    State: 37-Andhra Pradesh
                    
                    a
                    
                    varistors 180V(MOV14D181K) :
                    Voltage(MAKE-BOURNS)
                    
                    %7.00, % 252.00 (18%) = 1,652.00
                    
                    Sub Total % 1,400.00
                    Invoice Amount In Words IGST@18% 252.00
                    One Thousand Six Hundred Fifty Two Rupees only
                    
                    Total = 1,652.00
                    Terms And Conditions Received % 1,652.00
                    Thanks for doing business with us! Balance % 0.00
                    
                    Account No : 1200983850357
                    IFSC Code : CNRB002603
                    BANK : CANARA BANK
"""

**if I'm doing any thing wrong or there is any other efficient way to do it let me know. Any help will be greatful**