Add E2E example for metadata field functionality

Co-Authored-By: Aaron de Mello <[email protected]>

Author: devin-ai-integration[bot]

examples/metadata_field_demo/README.md

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+# Metadata Field Example
+
+This example demonstrates how to use metadata fields when creating drafts and sending messages using the Nylas Python SDK.
+
+## Features
+
+- Create drafts with custom metadata fields
+- Send messages with custom metadata fields
+- Error handling and environment variable configuration
+- Clear output and status messages
+
+## Prerequisites
+
+1. A Nylas account with API access
+2. Python 3.x installed
+3. The Nylas Python SDK installed (`pip install nylas`)
+
+## Setup
+
+1. Set your environment variables:
+```bash
+export NYLAS_API_KEY="your_api_key"
+export NYLAS_GRANT_ID="your_grant_id"
+export TEST_EMAIL="[email protected]"  # Optional
+```
+
+2. Run the example:
+```bash
+python metadata_example.py
+```
+
+## Example Output
+
+```
+Demonstrating Metadata Field Usage
+=================================
+
+1. Creating draft with metadata...
+✓ Created draft with ID: draft-abc123
+  Request ID: req-xyz789
+
+2. Sending message with metadata...
+✓ Sent message with ID: msg-def456
+  Request ID: req-uvw321
+
+Example completed successfully!
+```
+
+## Error Handling
+
+The example includes proper error handling for:
+- Missing environment variables
+- API authentication errors
+- Draft creation failures
+- Message sending failures
+
+## Documentation
+
+For more information about the Nylas Python SDK and its features, visit:
+- [Nylas Python SDK Documentation](https://developer.nylas.com/docs/sdks/python/)
+- [Nylas API Reference](https://developer.nylas.com/docs/api/)

examples/metadata_field_demo/metadata_example.py

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+#!/usr/bin/env python3
+"""
+Nylas SDK Example: Using Metadata Fields with Drafts and Messages
+
+This example demonstrates how to use metadata fields when creating drafts
+and sending messages using the Nylas Python SDK.
+
+Required Environment Variables:
+    NYLAS_API_KEY: Your Nylas API key
+    NYLAS_GRANT_ID: Your Nylas grant ID
+    TEST_EMAIL: Email address for sending test messages (optional)
+
+Usage:
+    export NYLAS_API_KEY="your_api_key"
+    export NYLAS_GRANT_ID="your_grant_id"
+    export TEST_EMAIL="[email protected]"
+    python metadata_example.py
+"""
+
+import os
+import sys
+from typing import Dict, Any, Optional
+from nylas import Client
+from nylas.models.errors import NylasAPIError
+
+
+def get_env_or_exit(var_name: str, required: bool = True) -> Optional[str]:
+    """Get an environment variable or exit if required and not found."""
+    value = os.getenv(var_name)
+    if required and not value:
+        print(f"Error: {var_name} environment variable is required")
+        sys.exit(1)
+    return value
+
+
+def create_draft_with_metadata(
+    client: Client, grant_id: str, metadata: Dict[str, Any], recipient: str
+) -> str:
+    """Create a draft message with metadata fields."""
+    try:
+        draft_request = {
+            "subject": "Test Draft with Metadata",
+            "to": [{"email": recipient}],
+            "body": "This is a test draft with metadata fields.",
+            "metadata": metadata
+        }
+
+        draft, request_id = client.drafts.create(
+            identifier=grant_id,
+            request_body=draft_request
+        )
+        print(f"✓ Created draft with ID: {draft.id}")
+        print(f"  Request ID: {request_id}")
+        return draft.id
+    except NylasAPIError as e:
+        print(f"✗ Failed to create draft: {e}")
+        sys.exit(1)
+
+
+def send_message_with_metadata(
+    client: Client, grant_id: str, metadata: Dict[str, Any], recipient: str
+) -> None:
+    """Send a message directly with metadata fields."""
+    try:
+        message_request = {
+            "subject": "Test Message with Metadata",
+            "to": [{"email": recipient}],
+            "body": "This is a test message with metadata fields.",
+            "metadata": metadata
+        }
+
+        message, request_id = client.messages.send(
+            identifier=grant_id,
+            request_body=message_request
+        )
+        print(f"✓ Sent message with ID: {message.id}")
+        print(f"  Request ID: {request_id}")
+    except NylasAPIError as e:
+        print(f"✗ Failed to send message: {e}")
+        sys.exit(1)
+
+
+def main():
+    """Main function demonstrating metadata field usage."""
+    # Get required environment variables
+    api_key = get_env_or_exit("NYLAS_API_KEY")
+    grant_id = get_env_or_exit("NYLAS_GRANT_ID")
+    recipient = get_env_or_exit("TEST_EMAIL", required=False) or "[email protected]"
+
+    # Initialize Nylas client
+    client = Client(
+        api_key=api_key,
+    )
+
+    # Example metadata
+    metadata = {
+        "campaign_id": "example-123",
+        "user_id": "user-456",
+        "custom_field": "test-value"
+    }
+
+    print("\nDemonstrating Metadata Field Usage")
+    print("=================================")
+
+    # Create a draft with metadata
+    print("\n1. Creating draft with metadata...")
+    draft_id = create_draft_with_metadata(client, grant_id, metadata, recipient)
+
+    # Send a message with metadata
+    print("\n2. Sending message with metadata...")
+    send_message_with_metadata(client, grant_id, metadata, recipient)
+
+    print("\nExample completed successfully!")
+
+
+if __name__ == "__main__":
+    main()