Issue: Error streaming a video file to GenAI from node.js for content generation

[phildehovre]

Hi, I am trying to connect a very simple node.js server running on localhost to upload a single video, get it processed by GenAI where it would choose from a series of keywords (from a given list) to describe said video.

I managed to wire everything up via trial-error, but this version of the code gives me some very cryptic error feedback:

Error: 400 Bad Request
Error Details:
Code: 400

Message: Invalid value at 'file.size_bytes' (TYPE_INT64), "undefined"

Status: INVALID_ARGUMENT

Field Violations:
Field: file.size_bytes
Description: Invalid value at 'file.size_bytes' (TYPE_INT64), "undefined"

As far as troubleshooting, I have looked at the docs but could not find an example that even remotely resembles what I am trying to accomplish. I have console.log'ed the heck at out of every env variable, every config params, every bit of the request object and it all looks correct. I am obviously missing something!

Thank you in advance for your help, I am here for any clarification.

The route:

https://github.com/phildehovre/hpm-node-api/blob/master/routes/analyseRoutes.js

const upload = multer({ storage: multer.memoryStorage() });

router.use('/analyse',upload.single("videos"), analyseRoutes) 

The controller:

https://github.com/phildehovre/hpm-node-api/blob/master/controllers/analyseControllers.js

const {GoogleGenAI, createUserContent, createPartFromUri} = require('@google/genai')
const { GoogleAuth } = require('google-auth-library');


const GOOGLE_APPLICATION_CREDENTIALS = process.env.GOOGLE_APPLICATION_CREDENTIALS;
const GOOGLE_API_KEY = process.env.GOOGLE_API_KEY;
const GOOGLE_CLIENT_EMAIL = process.env.GOOGLE_CLIENT_EMAIL;
const GOOGLE_PRIVATE_KEY = process.env.GOOGLE_PRIVATE_KEY.replace(/\\n/g, '\n'); 

if (!GOOGLE_APPLICATION_CREDENTIALS) {
  console.error('Error: GOOGLE_APPLICATION_CREDENTIALS environment variable is not set.');
}

const auth = new GoogleAuth({
  credentials: {
    client_email: GOOGLE_CLIENT_EMAIL,
    private_key: GOOGLE_PRIVATE_KEY,
  },
  scopes: ['https://www.googleapis.com/auth/cloud-platform'],
});

const ai = new GoogleGenAI({ apiKey: GOOGLE_API_KEY });


async function uploadAndAnalyzeVideo(fileBuffer, mimeType) {
  const fileSize = fileBuffer.length;
  console.log(fileBuffer.length)
  console.log('File Size (inside function):', fileSize);

  if (!fileSize) {
    throw new Error('File size could not be determined.');
  }

  const uploadParams = {
    file: fileBuffer,
    size_bytes: fileSize,
    config: {
      mimeType: mimeType 
    }
  };

  console.log('Upload Parameters:', uploadParams);

   const myfile = await ai.files.upload(uploadParams)


const response = await ai.models.generateContent({
  model: "gemini-2.0-flash",
  contents: createUserContent([
    createPartFromUri(myfile.uri, mimeType), 
    process.env.PROMPT,
  ]),
});

  return response.text;
}

module.exports.analyse = async (req, res) => {
  console.log(req.file)
    try {
        const fileBuffer = req.file.buffer;
        const mimeType = req.file.mimetype;

        const adcClient = await auth.getClient();
        const credentials = await adcClient.getAccessToken();
        console.log('Application Default Credentials loaded');
    
        const analysisResult = await uploadAndAnalyzeVideo(fileBuffer, mimeType);
    
        res.status(200).json({ analysis: analysisResult });
      } catch (error) {
        res.status(500).json({ error: "Error processing video file.", details: error.message });
      }
}

[phildehovre]

Solution:

The docs were a bit scarce when it came to my use case, but the solution included less code than initially thought.

I hope this can be of use to someone.

// routes.js

const { Router } = require('express')
const analyseRoutes = require('./analyseRoutes.js')
const router = Router()
const multer = require('multer')

const upload = multer({ storage: multer.memoryStorage() });

router.use('/analyse',upload.single("videos"), analyseRoutes) 

module.exports= router;

// analyseRoutes.js

const {Router} = require('express')
const router = Router()
const analyseControllers = require('../controllers/analyseControllers.js')

router.post('', analyseControllers.analyseVideo)

module.exports = router;

// analyseControllers.js

const {createUserContent, createPartFromUri, Part} = require('@google/genai')
const { GoogleAuth } = require('google-auth-library');
const genAI = require('../services/genAI.js')

const approvedKeywords = [
  // ...List of keywords
];


exports.analyseVideo = async (req, res) => {
  console.log(req.file);
    try {
        if (!req.file) {
            return res.status(400).json({ error: 'No video file uploaded.' });
        }
        const videoBuffer = req.file.buffer;
        let mimeType = req.file.mimetype;

        if (mimeType == 'application/octet-stream') {
          mimeType='video/mov'
        }

        const promptText = process.env.PROMPT + ` Keywords: ${approvedKeywords.join(',')}` 

        const videoPart = {
            inlineData: {
                data: videoBuffer.toString('base64'),
                mimeType: mimeType
            }
        };

        const response = await genAI.models.generateContent({
            model: "gemini-2.0-flash", 
            contents: createUserContent([
                videoPart, 
                promptText,
            ]),
        });

        const analysis = response.candidates[0].content.parts[0].text;
        console.log(response)

        res.status(200).json({ analysis: analysis });

    } catch (error) {
        console.error('Error analyzing video:', error);
        res.status(500).json({ error: 'Failed to analyze video.', details: error.message });
    }
};