Couchbase is an award-winning distributed NoSQL cloud database that delivers unmatched versatility, performance, scalability, and financial value for all of your cloud, mobile, AI, and edge computing applications. This guide shows how to use load documents from couchbase database.

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Installation

npm
npm install @langchain/community @langchain/core couchbase

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Usage

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Querying for Documents from Couchbase

For more details on connecting to a Couchbase cluster, please check the Node.js SDK documentation. For help with querying for documents using SQL++ (SQL for JSON), please check the documentation. 
import { CouchbaseDocumentLoader } from "@langchain/community/document_loaders/web/couchbase";
import { Cluster } from "couchbase";

const connectionString = "couchbase://localhost"; // valid couchbase connection string
const dbUsername = "Administrator"; // valid database user with read access to the bucket being queried
const dbPassword = "Password"; // password for the database user

// query is a valid SQL++ query
const query = `
    SELECT h.* FROM \`travel-sample\`.inventory.hotel h
    WHERE h.country = 'United States'
    LIMIT 1
`;

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Connect to Couchbase Cluster

const couchbaseClient = await Cluster.connect(connectionString, {
  username: dbUsername,
  password: dbPassword,
  configProfile: "wanDevelopment",
});

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Create the Loader

const loader = new CouchbaseDocumentLoader(
  couchbaseClient, // The connected couchbase cluster client
  query // A valid SQL++ query which will return the required data
);

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Load Documents

You can fetch the documents by calling the load method of the loader. It will return a list with all the documents. If you want to avoid this blocking call, you can call lazy_load method that returns an Iterator. 
// using load method
docs = await loader.load();
console.log(docs);

// using lazy_load
for await (const doc of this.lazyLoad()) {
  console.log(doc);
  break; // break based on required condition
}

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Specifying Fields with Content and Metadata

The fields that are part of the Document content can be specified using the pageContentFields parameter. The metadata fields for the Document can be specified using the metadataFields parameter. 
const loaderWithSelectedFields = new CouchbaseDocumentLoader(
  couchbaseClient,
  query,
  // pageContentFields
  [
    "address",
    "name",
    "city",
    "phone",
    "country",
    "geo",
    "description",
    "reviews",
  ],
  ["id"] // metadataFields
);

const filtered_docs = await loaderWithSelectedFields.load();
console.log(filtered_docs);