Extract structured data from a PDF using an LLM (like Claude) via the AWS SDK with Bedrock

pdf_extractor.rb

# Query an LLM like Claude using AWS Bedrock to extract structured data from a PDF
class PdfExtractor
  require 'aws-sdk-bedrockruntime'
  require 'json'

  # https://docs.aws.amazon.com/bedrock/latest/userguide/models-supported.html
  CLAUDE_3_5_HAIKU_MODEL_ID = 'anthropic.claude-3-5-haiku-20241022-v1:0'

  DEFAULT_PROMPT = <<~PROMPT
    You are an expert at extracting invoice information from PDFs.

    Extract the following information from this document in JSON format
    - date_of_invoice: The date when the invoice was issued (YYYY-MM-DD format)
    - invoice_number: The invoice number
    - invoice_amount: The total amount of the invoice
    ...

    Some important notes:
    - Pay special attention to table structures that might contain transaction details
    - Always return an array of extracted data in the JSON - most PDF documents will only have one transaction, but some may have multiple
    - convert all numbers from comma separated numbers like 424,405 to the integer like 424405

    If you're unsure about any value, mark it as null and explain why in the reasoning.

    Return the JSON data stucture only
  PROMPT

  def initialize
    @bedrock = Aws::BedrockRuntime::Client.new(
      region: "us-west-2",
      access_key_id: ENV.fetch('AWS_ACCESS_KEY_ID', nil),
      secret_access_key: ENV.fetch('AWS_SECRET_ACCESS_KEY', nil),
    )
  end

  def analyze_pdf(pdf_url: "spec/fixtures/invoice-sample.pdf", prompt: DEFAULT_PROMPT, model_id: CLAUDE_3_5_HAIKU_MODEL_ID)
    response = @bedrock.converse(
      model_id: model_id,
      messages: [
        {
          role: "user",
          content: [
            {
              document: {
                name: "Document 1",
                format: "pdf",
                source: {
                  bytes: File.read(pdf_url)
                }
              }
            },
            { text: prompt }
          ]
        }
      ]
    )
    JSON.parse(response.output.message.content.first.text)
  rescue Aws::BedrockRuntime::Errors::ServiceError => e
    Rails.logger.error("AWS Bedrock error: #{e.message}")
    raise "Failed to analyze PDF: #{e.message}"
  rescue JSON::ParserError => e
    Rails.logger.error("JSON parsing error: #{e.message}")
    raise "Failed to parse Bedrock response: #{e.message}"
  end
end