Processing Import Results in Your Application

For more information on the onResults callback, see the Reference documentation.

Here we show how to handle results directly in the browser, using Google Firebase as an example (unlike an RDBMS like Postgres, Firebase allows for direct browser connections). To handle results on a server, either send the onResults data to an API you control or subscribe to a webhook. This example assumes you have installed the Firebase SDK.

import { initializeApp } from 'firebase/app';
import { getFirestore } from 'firebase/firestore';
import { addDoc, collection } from 'firebase/firestore';

const firebaseConfig = {
  ...
};

const app = initializeApp(firebaseConfig);
const db = getFirestore(app);

The onResults callback returns an array of objects, where each object represents a record. The callback also receives a metadata object containing information about the import process.

dromo.onResults(function (data, metadata) {
  console.log('Import metadata:', metadata);

  // Loop through each item in the data array and add it as a document in Firebase
  data.forEach(async (record) => {
    try {
      const docRef = await addDoc(collection(db, 'collectionName'), record);
      console.log(`Document written with ID: ${docRef.id}`);
    } catch (e) {
      console.error('Error adding document: ', e);
    }
  })
});

Working with Metadata

The metadata object contains useful information about the import:

dromo.onResults(function (data, metadata) {
  console.log('Total rows processed:', metadata.totalRows);
  console.log('Valid rows:', metadata.validRows);
  console.log('Invalid rows:', metadata.invalidRows);
  console.log('Original headers:', metadata.rawHeaders);
});

Handling Unmapped Columns

If you’ve enabled the passThroughUnmappedColumns setting, your data will include unmapped columns that weren’t part of your schema:

dromo.onResults(function (data, metadata) {
  data.forEach(async (record) => {
    // Process main mapped data
    const mappedData = { ...record };
    delete mappedData.$unmapped;

    // Handle unmapped columns separately if they exist
    if (record.$unmapped && metadata.rawHeaders) {
      const unmappedData = {};
      Object.entries(record.$unmapped).forEach(([index, value]) => {
        const headerName = metadata.rawHeaders[parseInt(index)];
        if (headerName) {
          unmappedData[headerName] = value;
        }
      });

      // Store unmapped data in a separate collection or field
      console.log('Unmapped data:', unmappedData);
    }

    // Save to Firebase
    await addDoc(collection(db, 'collectionName'), mappedData);
  });
});

For a comprehensive guide on working with unmapped columns, see the Accessing Unmapped Columns guide.

Getting Started

Guides

Reference

FAQ & Changelog

Processing Import Results in Your Application

Working with Metadata

Handling Unmapped Columns

​Working with Metadata

​Handling Unmapped Columns

Working with Metadata

Handling Unmapped Columns