Image Generation or Editing Callbacks

When you submit image generation or editing tasks to the NanoBanana API, you can set a callback address through the callBackUrl parameter. After the task is completed, the system will automatically push the results to your specified address.

Callback Mechanism Overview

The callback mechanism eliminates the need for you to poll the API to query task status. The system will actively push task completion results to your server.

Callback Timing

The system will send callback notifications in the following situations:

Image generation or editing task completed successfully
Image generation or editing task failed
Error occurred during task processing

Callback Method

HTTP Method: POST
Content Type: application/json
Timeout Setting: 15 seconds

Callback Request Format

After task completion, the system will send a POST request to your callBackUrl in the following format:

{
  "msg": "Image generated successfully.",
  "code": 200,
  "data": {
    "taskId": "9e4286b7b27960dfeb8e1d279b50b28d",
    "info": {
      "resultImageUrl": "https://tempfile.aiquickdraw.com/r/9e4286b7b27960dfeb8e1d279b50b28d_1756467493.jpg"
    }
  }
}

{
  "code": 400,
  "msg": "Your prompt has been flagged for violating content policy",
  "data": {
    "taskId": "task12345",
    "info": {
      "resultImageUrl": ""
    }
  }
}

{
  "code": 501,
  "msg": "Image generation task failed",
  "data": {
    "taskId": "task12345",
    "info": {
      "resultImageUrl": ""
    }
  }
}

{
  "code": 500,
  "msg": "Internal error, please try again later",
  "data": {
    "taskId": "task12345",
    "info": {
      "resultImageUrl": ""
    }
  }
}

Status Code Description

integer

required

Callback status code indicating task processing result:

Status Code	Description
200	Success - Image generation successful
400	Failed - Your prompt was flagged for violating content policy
500	Failed - Internal error, please try again later
501	Failed - Image generation task failed

string

required

Status message providing detailed status description

string

required

Task ID, consistent with the taskId returned when you submitted the task

string

Generated image URL on our server. Only exists on success.

Callback Reception Examples

Here are example codes for receiving callbacks in popular programming languages:

Node.js
Python
PHP

const express = require('express');
const fs = require('fs');
const https = require('https');
const app = express();

app.use(express.json());

app.post('/nanobanana-image-callback', (req, res) => {
  const { code, msg, data } = req.body;
  
  console.log('Received NanoBanana image generation callback:', {
    taskId: data.taskId,
    status: code,
    message: msg
  });
  
  if (code === 200) {
    // Task completed successfully
    console.log('NanoBanana image generation completed successfully');
    
    const { taskId, info } = data;
    const { resultImageUrl } = info;
    
    console.log(`Generated image URL: ${resultImageUrl}`);
    
    // Download the generated image
    if (resultImageUrl) {
      downloadFile(resultImageUrl, `nanobanana_result_${taskId}.jpg`)
        .then(() => console.log('Generated image downloaded successfully'))
        .catch(err => console.error('Failed to download generated image:', err));
    }
    
  } else {
    // Task failed
    console.log('NanoBanana image generation failed:', msg);
    
    // Handle specific error types
    if (code === 400) {
      console.log('Content policy violation - please adjust your prompt');
    } else if (code === 500) {
      console.log('Internal error - please try again later');
    } else if (code === 501) {
      console.log('Generation task failed - may need to adjust parameters');
    }
  }
  
  // Return 200 status code to confirm callback receipt
  res.status(200).json({ status: 'received' });
});

// Helper function: download file
function downloadFile(url, filename) {
  return new Promise((resolve, reject) => {
    const file = fs.createWriteStream(filename);
    
    https.get(url, (response) => {
      if (response.statusCode === 200) {
        response.pipe(file);
        file.on('finish', () => {
          file.close();
          resolve();
        });
      } else {
        reject(new Error(`HTTP ${response.statusCode}`));
      }
    }).on('error', reject);
  });
}

app.listen(3000, () => {
  console.log('Callback server running on port 3000');
});

from flask import Flask, request, jsonify
import requests
import os

app = Flask(__name__)

@app.route('/nanobanana-image-callback', methods=['POST'])
def handle_callback():
    data = request.json
    
    code = data.get('code')
    msg = data.get('msg')
    callback_data = data.get('data', {})
    task_id = callback_data.get('taskId')
    info = callback_data.get('info', {})
    result_image_url = info.get('resultImageUrl')
    
    print(f"Received NanoBanana image generation callback:")
    print(f"Task ID: {task_id}")
    print(f"Status: {code}, Message: {msg}")
    
    if code == 200:
        # Task completed successfully
        print("NanoBanana image generation completed successfully")
        
        print(f"Generated image URL: {result_image_url}")
        
        # Download the generated image
        if result_image_url:
            try:
                result_filename = f"nanobanana_result_{task_id}.jpg"
                download_file(result_image_url, result_filename)
                print(f"Generated image downloaded as {result_filename}")
            except Exception as e:
                print(f"Failed to download generated image: {e}")
                
    else:
        # Task failed
        print(f"NanoBanana image generation failed: {msg}")
        
        # Handle specific error types
        if code == 400:
            print("Content policy violation - please adjust your prompt")
        elif code == 500:
            print("Internal error - please try again later")
        elif code == 501:
            print("Generation task failed - may need to adjust parameters")
    
    # Return 200 status code to confirm callback receipt
    return jsonify({'status': 'received'}), 200

def download_file(url, filename):
    """Download file from URL and save locally"""
    response = requests.get(url, stream=True)
    response.raise_for_status()
    
    os.makedirs('downloads', exist_ok=True)
    filepath = os.path.join('downloads', filename)
    
    with open(filepath, 'wb') as f:
        for chunk in response.iter_content(chunk_size=8192):
            f.write(chunk)

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=3000)

<?php
header('Content-Type: application/json');

// Get POST data
$input = file_get_contents('php://input');
$data = json_decode($input, true);

$code = $data['code'] ?? null;
$msg = $data['msg'] ?? '';
$callbackData = $data['data'] ?? [];
$taskId = $callbackData['taskId'] ?? '';
$info = $callbackData['info'] ?? [];
$resultImageUrl = $info['resultImageUrl'] ?? '';

error_log("Received NanoBanana image generation callback:");
error_log("Task ID: $taskId");
error_log("Status: $code, Message: $msg");

if ($code === 200) {
    // Task completed successfully
    error_log("NanoBanana image generation completed successfully");
    
    error_log("Generated image URL: $resultImageUrl");
    
    // Download the generated image
    if (!empty($resultImageUrl)) {
        try {
            $resultFilename = "nanobanana_result_{$taskId}.jpg";
            downloadFile($resultImageUrl, $resultFilename);
            error_log("Generated image downloaded as $resultFilename");
        } catch (Exception $e) {
            error_log("Failed to download generated image: " . $e->getMessage());
        }
    }
    
} else {
    // Task failed
    error_log("NanoBanana image generation failed: $msg");
    
    // Handle specific error types
    if ($code === 400) {
        error_log("Content policy violation - please adjust your prompt");
    } elseif ($code === 500) {
        error_log("Internal error - please try again later");
    } elseif ($code === 501) {
        error_log("Generation task failed - may need to adjust parameters");
    }
}

// Return 200 status code to confirm callback receipt
http_response_code(200);
echo json_encode(['status' => 'received']);

function downloadFile($url, $filename) {
    $downloadDir = 'downloads';
    if (!is_dir($downloadDir)) {
        mkdir($downloadDir, 0755, true);
    }
    
    $filepath = $downloadDir . '/' . $filename;
    
    $fileContent = file_get_contents($url);
    if ($fileContent === false) {
        throw new Exception("Failed to download file from URL");
    }
    
    $result = file_put_contents($filepath, $fileContent);
    if ($result === false) {
        throw new Exception("Failed to save file locally");
    }
}
?>

Best Practices

Callback URL Configuration Recommendations

Use HTTPS: Ensure callback URL uses HTTPS protocol for secure data transmission
Verify Source: Verify the legitimacy of request sources in callback handling
Idempotent Processing: The same taskId may receive multiple callbacks, ensure processing logic is idempotent
Quick Response: Callback handling should return 200 status code quickly to avoid timeout
Asynchronous Processing: Complex business logic should be processed asynchronously to avoid blocking callback response
Timely Download: Download image files promptly after receiving successful callbacks

Important Reminders

Callback URL must be a publicly accessible address
Server must respond within 15 seconds, otherwise it will be considered timeout
After 3 consecutive retry failures, the system will stop sending callbacks
Ensure stability of callback handling logic to avoid callback failures due to exceptions
Need to handle multiple error status codes (400, 500, 501), implement complete error handling
Pay attention to content policy violation issues and adjust prompts timely

Troubleshooting

If you haven’t received callback notifications, please check the following:

Network Connection Issues

Confirm callback URL is accessible from the public internet
Check firewall settings to ensure inbound requests are not blocked
Verify domain name resolution is correct

Server Response Issues

Ensure server returns HTTP 200 status code within 15 seconds
Check server logs for error information
Verify interface path and HTTP method are correct

Content Format Issues

Confirm received POST request body is in JSON format
Check if Content-Type is application/json
Verify JSON parsing is correct

Image Processing Issues

Confirm image URL is accessible
Check image download permissions and network connection
Verify image save path and permissions
Implement reasonable image download and storage logic

Content Policy Issues

Review content policy violation prompts in error messages
Adjust flagged prompt content
Ensure prompts comply with platform content guidelines
Check for sensitive or inappropriate content

Task Failure Issues

Check if generation parameters are reasonable
Verify input image format and quality
Confirm prompt length and format
Consider adjusting generation parameters and retry

Alternative Solution

If you cannot use the callback mechanism, you can also use polling:

Polling Query Results

Use the get task details interface to periodically query task status, recommended every 30 seconds.

Getting started

NanoBanana API

Common API

Image Generation or Editing Callbacks

Callback Mechanism Overview

Callback Timing

Callback Method

Callback Request Format

Status Code Description

Callback Reception Examples

Best Practices

Callback URL Configuration Recommendations

Important Reminders

Troubleshooting

Alternative Solution

Polling Query Results

​Callback Mechanism Overview

​Callback Timing

​Callback Method

​Callback Request Format

​Status Code Description

​Callback Reception Examples

​Best Practices

​Callback URL Configuration Recommendations

​Important Reminders

​Troubleshooting

​Alternative Solution

Polling Query Results

Callback Mechanism Overview

Callback Timing

Callback Method

Callback Request Format

Status Code Description

Callback Reception Examples

Best Practices

Callback URL Configuration Recommendations

Important Reminders

Troubleshooting

Alternative Solution