---
title: "LLMMetadataExtractor"
id: llmmetadataextractor
slug: "/llmmetadataextractor"
description: "Extracts metadata from documents using a Large Language Model. The metadata is extracted by providing a prompt to a LLM that generates it."
---

# LLMMetadataExtractor

Extracts metadata from documents using a Large Language Model. The metadata is extracted by providing a prompt to a LLM that generates it.

<div className="key-value-table">

|  |  |
| --- | --- |
| **Most common position in a pipeline** | After [PreProcessors](../preprocessors.mdx) in an indexing pipeline |
| **Mandatory init variables** | `prompt`: The prompt to instruct the LLM on how to extract metadata from the document  <br /> <br />`chat_generator`: A Chat Generator instance which represents the LLM configured to return a JSON object |
| **Mandatory run variables** | `documents`: A list of documents |
| **Output variables** | `documents`: A list of documents |
| **API reference** | [Extractors](/reference/extractors-api) |
| **GitHub link** | https://github.com/deepset-ai/haystack/blob/main/haystack/components/extractors/llm_metadata_extractor.py |

</div>

## Overview

The `LLMMetadataExtractor` extraction relies on an LLM and a prompt to perform the metadata extraction. At initialization time, it expects an LLM, a Haystack Generator, and a prompt describing the metadata extraction process.

The prompt should have a variable called `document` that will point to a single document in the list of documents. So, to access the content of the document, you can use `{{ document.content }}` in the prompt.

At runtime, it expects a list of documents and will run the LLM on each document in the list, extracting metadata from the document. The metadata will be added to the document's metadata field.

If the LLM fails to extract metadata from a document, it will be added to the `failed_documents` list. The failed documents' metadata will contain the keys `metadata_extraction_error` and `metadata_extraction_response`.

These documents can be re-run with another extractor to extract metadata using the `metadata_extraction_response` and `metadata_extraction_error` in the prompt.

The current implementation supports the following Haystack Generators:

- [OpenAIChatGenerator](../generators/openaichatgenerator.mdx)
- [AzureOpenAIChatGenerator](../generators/azureopenaichatgenerator.mdx)
- [AmazonBedrockChatGenerator](../generators/amazonbedrockchatgenerator.mdx)
- [VertexAIGeminiChatGenerator](../generators/vertexaigeminichatgenerator.mdx)

## Usage

Here's an example of using the `LLMMetadataExtractor` to extract named entities and add them to the document's metadata.

First, the mandatory imports:

```python
from haystack import Document
from haystack.components.extractors.llm_metadata_extractor import LLMMetadataExtractor
from haystack.components.generators.chat import OpenAIChatGenerator
```

Then, define some documents:

```python
docs = [
    Document(
        content="deepset was founded in 2018 in Berlin, and is known for its Haystack framework",
    ),
    Document(
        content="Hugging Face is a company founded in New York, USA and is known for its Transformers library",
    ),
]
```

And now, a prompt that extracts named entities from the documents:

```python
NER_PROMPT = """
    -Goal-
    Given text and a list of entity types, identify all entities of those types from the text.

    -Steps-
    1. Identify all entities. For each identified entity, extract the following information:
    - entity_name: Name of the entity, capitalized
    - entity_type: One of the following types: [organization, product, service, industry]
    Format each entity as a JSON like: {"entity": <entity_name>, "entity_type": <entity_type>}

    2. Return output in a single list with all the entities identified in steps 1.

    -Examples-
    ######################
    Example 1:
    entity_types: [organization, person, partnership, financial metric, product, service, industry, investment strategy, market trend]
    text: Another area of strength is our co-brand issuance. Visa is the primary network partner for eight of the top
    10 co-brand partnerships in the US today and we are pleased that Visa has finalized a multi-year extension of
    our successful credit co-branded partnership with Alaska Airlines, a portfolio that benefits from a loyal customer
    base and high cross-border usage.
    We have also had significant co-brand momentum in CEMEA. First, we launched a new co-brand card in partnership
    with Qatar Airways, British Airways and the National Bank of Kuwait. Second, we expanded our strong global
    Marriott relationship to launch Qatar's first hospitality co-branded card with Qatar Islamic Bank. Across the
    United Arab Emirates, we now have exclusive agreements with all the leading airlines marked by a recent
    agreement with Emirates Skywards.
    And we also signed an inaugural Airline co-brand agreement in Morocco with Royal Air Maroc. Now newer digital
    issuers are equally
    ------------------------
    output:
    {"entities": [{"entity": "Visa", "entity_type": "company"}, {"entity": "Alaska Airlines", "entity_type": "company"}, {"entity": "Qatar Airways", "entity_type": "company"}, {"entity": "British Airways", "entity_type": "company"}, {"entity": "National Bank of Kuwait", "entity_type": "company"}, {"entity": "Marriott", "entity_type": "company"}, {"entity": "Qatar Islamic Bank", "entity_type": "company"}, {"entity": "Emirates Skywards", "entity_type": "company"}, {"entity": "Royal Air Maroc", "entity_type": "company"}]}
    #############################
    -Real Data-
    ######################
    entity_types: [company, organization, person, country, product, service]
    text: {{ document.content }}
    ######################
    output:
    """
```

Now, define a simple indexing pipeline that uses the `LLMMetadataExtractor` to extract named entities from the documents:

```python
chat_generator = OpenAIChatGenerator(
  generation_kwargs={
    "max_tokens": 500,
    "temperature": 0.0,
    "seed": 0,
    "response_format": {"type": "json_object"},
  },
  max_retries=1,
  timeout=60.0,
)

extractor = LLMMetadataExtractor(
  prompt=NER_PROMPT,
  chat_generator=generator,
  expected_keys=["entities"],
  raise_on_failure=False,
)

extractor.run(documents=docs)

>> {'documents': [
  Document(id=.., content: 'deepset was founded in 2018 in Berlin, and is known for its Haystack framework',
           meta: {'entities': [{'entity': 'deepset', 'entity_type': 'company'}, {'entity': 'Berlin', 'entity_type': 'city'},
                               {'entity': 'Haystack', 'entity_type': 'product'}]}),
  Document(id=.., content: 'Hugging Face is a company that was founded in New York, USA and is known for its Transformers library',
           meta: {'entities': [
             {'entity': 'Hugging Face', 'entity_type': 'company'}, {'entity': 'New York', 'entity_type': 'city'},
             {'entity': 'USA', 'entity_type': 'country'}, {'entity': 'Transformers', 'entity_type': 'product'}
           ]})
]
    'failed_documents': []
   }
>>
```
