supporting blog content human-in-the-loop-with-langgraph-and-elasticsearch

supporting-blog-content/human-in-the-loop-with-langgraph-and-elasticsearch/README.md

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+# LangGraph + Elasticsearch Human-in-the-Loop
+
+Flight search application using LangGraph for human-in-the-loop workflow and Elasticsearch for vector search.
+
+## Prerequisites
+
+- Node.js 18+
+- Elasticsearch instance
+- OpenAI API key
+
+## Installation
+
+### Quick Install 
+
+```bash
+npm install
+```
+
+### Manual Install (Alternative)
+
+```bash
+npm install @elastic/elasticsearch @langchain/community @langchain/core @langchain/langgraph @langchain/openai dotenv --legacy-peer-deps
+npm install --save-dev tsx 
+```
+
+## Configuration
+
+Create a `.env` file in the root directory:
+
+```env
+ELASTICSEARCH_ENDPOINT=https://your-elasticsearch-instance.com
+ELASTICSEARCH_API_KEY=your-api-key
+OPENAI_API_KEY=your-openai-api-key
+```
+
+## Usage
+
+```bash
+npm start
+```
+
+## Features
+
+- 🔍 Vector search with Elasticsearch
+- 🤖 LLM-powered natural language selection
+- 👤 Human-in-the-loop workflow with LangGraph
+- 📊 Workflow visualization (generates `workflow_graph.png`)
+
+## Workflow
+
+1. **Retrieve Flights** - Search Elasticsearch with vector similarity
+2. **Evaluate Results** - Auto-select if 1 result, show options if multiple
+3. **Show Results** - Display flight options to user
+4. **Request User Choice** - Pause workflow for user input (HITL)
+5. **Disambiguate & Answer** - Use LLM to interpret selection and return final answer
+

supporting-blog-content/human-in-the-loop-with-langgraph-and-elasticsearch/dataIngestion.ts

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+import { ElasticVectorSearch } from "@langchain/community/vectorstores/elasticsearch";
+import { OpenAIEmbeddings } from "@langchain/openai";
+import { Client } from "@elastic/elasticsearch";
+import { readFile } from "node:fs/promises";
+import dotenv from "dotenv";
+
+dotenv.config();
+
+const VECTOR_INDEX = "flights-offerings";
+
+// Types
+export interface DocumentMetadata {
+  from_city: string;
+  to_city: string;
+  airport_code: string;
+  airport_name: string;
+  country: string;
+  airline: string;
+  date: string;
+  price: number;
+  time_approx: string;
+  title: string;
+}
+
+export interface Document {
+  pageContent: string;
+  metadata: DocumentMetadata;
+}
+
+interface RawDocument {
+  pageContent?: string;
+  text?: string;
+  metadata?: DocumentMetadata;
+}
+
+const esClient = new Client({
+  node: process.env.ELASTICSEARCH_ENDPOINT!,
+  auth: {
+    apiKey: process.env.ELASTICSEARCH_API_KEY!,
+  },
+});
+
+const embeddings = new OpenAIEmbeddings({
+  model: "text-embedding-3-small",
+});
+
+const vectorStore = new ElasticVectorSearch(embeddings, {
+  client: esClient,
+  indexName: VECTOR_INDEX,
+});
+
+/**
+ * Load dataset from a JSON file
+ * @param path - Path to the JSON file
+ * @returns Array of documents with pageContent and metadata
+ */
+export async function loadDataset(path: string): Promise<Document[]> {
+  const raw = await readFile(path, "utf-8");
+  const data: RawDocument[] = JSON.parse(raw);
+
+  return data.map((d) => ({
+    pageContent: String(d.pageContent ?? d.text ?? ""),
+    metadata: (d.metadata ?? {}) as DocumentMetadata,
+  }));
+}
+
+/**
+ * Ingest data into Elasticsearch vector store
+ * Creates the index if it doesn't exist and loads initial dataset
+ */
+export async function ingestData(): Promise<void> {
+  const vectorExists = await esClient.indices.exists({ index: VECTOR_INDEX });
+
+  if (!vectorExists) {
+    console.log("CREATING VECTOR INDEX...");
+
+    await esClient.indices.create({
+      index: VECTOR_INDEX,
+      mappings: {
+        properties: {
+          text: { type: "text" },
+          embedding: {
+            type: "dense_vector",
+            dims: 1536,
+            index: true,
+            similarity: "cosine",
+          },
+          metadata: {
+            type: "object",
+            properties: {
+              from_city: { type: "keyword" },
+              to_city: { type: "keyword" },
+              airport_code: { type: "keyword" },
+              airport_name: {
+                type: "text",
+                fields: {
+                  keyword: { type: "keyword" },
+                },
+              },
+              country: { type: "keyword" },
+              airline: { type: "keyword" },
+              date: { type: "date" },
+              price: { type: "integer" },
+              time_approx: { type: "keyword" },
+              title: {
+                type: "text",
+                fields: {
+                  keyword: { type: "keyword" },
+                },
+              },
+            },
+          },
+        },
+      },
+    });
+  }
+
+  const indexExists = await esClient.indices.exists({ index: VECTOR_INDEX });
+
+  if (indexExists) {
+    const indexCount = await esClient.count({ index: VECTOR_INDEX });
+    const documentCount = indexCount.count;
+
+    // Only ingest if index is empty
+    if (documentCount > 0) {
+      console.log(
+        `Index already contains ${documentCount} documents. Skipping ingestion.`
+      );
+      return;
+    }
+
+    console.log("INGESTING DATASET...");
+    const datasetPath = "./dataset.json";
+    const initialDocs = await loadDataset(datasetPath).catch(() => []);
+
+    await vectorStore.addDocuments(initialDocs);
+    console.log(`✅ Successfully ingested ${initialDocs.length} documents`);
+  }
+}
+
+export { VECTOR_INDEX };

supporting-blog-content/human-in-the-loop-with-langgraph-and-elasticsearch/dataset.json

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+[
+  {
+    "pageContent": "Ticket: Medellín (MDE) → Sao Paulo (GRU). 1 stop. Airline: AndeanSky.",
+    "metadata": {
+      "from_city": "Medellín",
+      "to_city": "Sao Paulo",
+      "airport_code": "GRU",
+      "airport_name": "Guarulhos International",
+      "country": "Brazil",
+      "airline": "AndeanSky",
+      "date": "2025-10-10",
+      "price": 480,
+      "time_approx": "7h 30m",
+      "title": "MDE → GRU (AndeanSky)"
+    }
+  },
+  {
+    "pageContent": "Ticket: Medellín (MDE) → Sao Paulo (CGH). 1 stop. Airline: CoffeeAir.",
+    "metadata": {
+      "from_city": "Medellín",
+      "to_city": "Sao Paulo",
+      "airport_code": "CGH",
+      "airport_name": "Congonhas",
+      "country": "Brazil",
+      "airline": "CoffeeAir",
+      "date": "2025-10-10",
+      "price": 455,
+      "time_approx": "8h 05m",
+      "title": "MDE → CGH (CoffeeAir)"
+    }
+  },
+  {
+    "pageContent": "Ticket: Medellín (MDE) → Tokyo (HND). 2 stops. Airline: CondorJet.",
+    "metadata": {
+      "from_city": "Medellín",
+      "to_city": "Tokyo",
+      "airport_code": "HND",
+      "airport_name": "Haneda",
+      "country": "Japan",
+      "airline": "CondorJet",
+      "date": "2025-11-05",
+      "price": 1290,
+      "time_approx": "22h 10m",
+      "title": "MDE → HND (CondorJet)"
+    }
+  },
+  {
+    "pageContent": "Ticket: Medellín (MDE) → Tokyo (NRT). 1–2 stops. Airline: CaribeWings.",
+    "metadata": {
+      "from_city": "Medellín",
+      "to_city": "Tokyo",
+      "airport_code": "NRT",
+      "airport_name": "Narita",
+      "country": "Japan",
+      "airline": "CaribeWings",
+      "date": "2025-11-05",
+      "price": 1215,
+      "time_approx": "23h 30m",
+      "title": "MDE → NRT (CaribeWings)"
+    }
+  },
+  {
+    "pageContent": "Ticket: Medellín (MDE) → New York (JFK). 1 stop. Airline: AndeanSky.",
+    "metadata": {
+      "from_city": "Medellín",
+      "to_city": "New York",
+      "airport_code": "JFK",
+      "airport_name": "John F. Kennedy International",
+      "country": "USA",
+      "airline": "AndeanSky",
+      "date": "2025-12-01",
+      "price": 340,
+      "time_approx": "6h 40m",
+      "title": "MDE → JFK (AndeanSky)"
+    }
+  },
+  {
+    "pageContent": "Ticket: Medellín (MDE) → New York (LGA). 1 stop. Airline: CoffeeAir.",
+    "metadata": {
+      "from_city": "Medellín",
+      "to_city": "New York",
+      "airport_code": "LGA",
+      "airport_name": "LaGuardia",
+      "country": "USA",
+      "airline": "CoffeeAir",
+      "date": "2025-12-01",
+      "price": 325,
+      "time_approx": "6h 55m",
+      "title": "MDE → LGA (CoffeeAir)"
+    }
+  },
+  {
+    "pageContent": "Ticket: Medellín (MDE) → London (LHR). 1 stop. Airline: CondorJet.",
+    "metadata": {
+      "from_city": "Medellín",
+      "to_city": "London",
+      "airport_code": "LHR",
+      "airport_name": "Heathrow",
+      "country": "UK",
+      "airline": "CondorJet",
+      "date": "2026-01-15",
+      "price": 890,
+      "time_approx": "14h 30m",
+      "title": "MDE → LHR (CondorJet)"
+    }
+  },
+  {
+    "pageContent": "Ticket: Medellín (MDE) → London (LGW). 1–2 stops. Airline: CaribeWings.",
+    "metadata": {
+      "from_city": "Medellín",
+      "to_city": "London",
+      "airport_code": "LGW",
+      "airport_name": "Gatwick",
+      "country": "UK",
+      "airline": "CaribeWings",
+      "date": "2026-01-15",
+      "price": 760,
+      "time_approx": "15h 10m",
+      "title": "MDE → LGW (CaribeWings)"
+    }
+  },
+  {
+    "pageContent": "Ticket: Medellín (MDE) → Paris (CDG). 1 stop. Airline: CoffeeAir.",
+    "metadata": {
+      "from_city": "Medellín",
+      "to_city": "Paris",
+      "airport_code": "CDG",
+      "airport_name": "Charles de Gaulle",
+      "country": "France",
+      "airline": "CoffeeAir",
+      "date": "2025-10-22",
+      "price": 720,
+      "time_approx": "13h 50m",
+      "title": "MDE → CDG (CoffeeAir)"
+    }
+  },
+  {
+    "pageContent": "Ticket: Medellín (MDE) → Paris (ORY). 1 stop. Airline: AndeanSky.",
+    "metadata": {
+      "from_city": "Medellín",
+      "to_city": "Paris",
+      "airport_code": "ORY",
+      "airport_name": "Orly",
+      "country": "France",
+      "airline": "AndeanSky",
+      "date": "2025-10-22",
+      "price": 695,
+      "time_approx": "13h 20m",
+      "title": "MDE → ORY (AndeanSky)"
+    }
+  }
+]