External Dependencies

In Infragate, functions can leverage external dependencies to extend their capabilities and perform complex operations.

The following is an example of a custom function that connects to a MongoDB database to retrieve and describe the schema of a specified database.

import { MongoClient } from "npm:mongodb@6.1.0";

interface Request {
  database: string; // Database name
  sampleSize?: number; // Number of documents to sample per collection (default = 10)
}

const username = process.env.MONGODB_USERNAME;
const password = process.env.MONGODB_PASSWORD;
const hostname = process.env.MONGODB_HOSTNAME;

// Connection URI
const uri = `mongodb+srv://${username}:${password}@${hostname}/?retryWrites=true&w=majority&appName=Cluster0`;

let client: MongoClient = undefined;

export async function handler(request: Request): Promise<any> {
  const { database, sampleSize = 10 } = request;

  if (!database) {
    return { error: "Missing 'database' field in request." };
  }

  try {

    if (!client) {
      client = new MongoClient(uri);
      await client.connect();
      console.log("Connected to MongoDB cluster");
    }


    const db = client.db(database);
    const collections = await db.listCollections().toArray();
    const schemaInfo: Record<string, Record<string, string>> = {};

    for (const col of collections) {
      const collection = db.collection(col.name);
      const docs = await collection.find({}).limit(sampleSize).toArray();

      const fieldTypes: Record<string, Set<string>> = {};

      // Only inspect top-level fields
      for (const doc of docs) {
        for (const [key, value] of Object.entries(doc)) {
          const type = Array.isArray(value)
            ? "array"
            : value === null
            ? "null"
            : typeof value === "object"
            ? "object"
            : typeof value;

          if (!fieldTypes[key]) fieldTypes[key] = new Set();
          fieldTypes[key].add(type);
        }
      }

      // Merge all observed types into a string representation
      const mergedTypes: Record<string, string> = {};
      for (const [field, types] of Object.entries(fieldTypes)) {
        mergedTypes[field] = Array.from(types).join(" | ");
      }

      schemaInfo[col.name] = mergedTypes;
    }

    return {
      database,
      schema: schemaInfo,
    };
  } catch (error) {
    console.error("Error describing schema:", error);
    return { error: error.message };
  }
}