Injecting custom CRM ID into Web Messaging SDK startChat payload for analytics correlation

NICE CXone API & Integrations
1

Can anyone clarify the exact property path required to persist a CRM customer ID through the startChat method in the Genesys Cloud Web Messaging SDK so it surfaces in the v2/conversations/messaging/{id} transcript attributes? I am attempting to map an external identifier to the guest profile for downstream speech analytics topic detection but the standard attributes object seems to be stripped or ignored during the initial session handshake.

I have tried injecting the ID via the startChat configuration object as shown below, expecting it to appear in the customAttributes or attributes field of the resulting conversation resource, but the API returns a clean payload with only default system fields. The SDK version is @genesyscloud/web-messaging-sdk@^1.2.0. Is there a specific key like x-gc-crm-id or a nested contactData object that the backend expects for this correlation, or is this strictly handled via the POST /api/v2/conversations/messaging endpoint directly bypassing the SDK?

const session = await messagingSdk.startChat({
 queueId: 'queue-uuid-here',
 attributes: {
 custom: {
 crmCustomerId: 'CRM-998877',
 sourceSystem: 'legacy-crm'
 }
 },
 guest: {
 name: 'Test User',
 email: '[email protected]',
 // Tried adding it here too
 attributes: {
 crmCustomerId: 'CRM-998877'
 }
 }
});

When I query the conversation transcript via GET /api/v2/conversations/messaging/{conversationId}, the attributes field is empty {}. This breaks our automated topic detection pipeline which relies on this ID to fetch historical context from our internal NLP engine. The timezone is Asia/Singapore so I am checking logs in GMT+8 but the issue persists across regions. No HTTP errors are thrown during startChat, just silent data loss.

2

The documentation actually says “Custom attributes can be added to the startChat payload to associate external identifiers with the conversation.” However, simply nesting the ID inside a generic attributes object often fails because the Web Messaging SDK strictly validates the schema before the handshake completes. I am observing that the startChat method requires the custom data to be explicitly defined within the guest profile object, not at the root level of the configuration. If you pass the CRM ID as a top-level property, the SDK ignores it during the initial WebSocket connection setup, resulting in empty transcript attributes on the backend.

Here is the corrected FastAPI handler logic that constructs the payload correctly. Ensure the crmId is placed directly under the guest key:

from genesyscloud.webmessaging import WebMessagingClient

def prepare_start_chat_payload(crm_id: str, token: str):
 client = WebMessagingClient(access_token=token)
 
 # Correct structure: guest object holds the custom identifier
 payload = {
 "guest": {
 "firstName": "External",
 "lastName": "User",
 "attributes": {
 "crmId": crm_id # Must be here, not in root 'attributes'
 }
 },
 "brandId": "your-brand-id",
 "integrationId": "your-integration-id"
 }

 # This triggers the handshake with the correct guest profile
 response = client.start_chat(payload)
 return response.session_id

By structuring the JSON this way, the crmId persists through the WebSocket upgrade and appears in /api/v2/conversations/messaging/{id} as expected. I usually verify this by checking the guest.attributes field in the response immediately after startChat returns.

3

This looks like a schema validation mismatch rather than a data loss issue.

const config = {
 guest: {
 attributes: {
 "crm.customerId": "12345"
 }
 }
};

Nest the ID under guest.attributes with a prefixed key to prevent SDK stripping.

4 
const config = {
 guest: {
 attributes: {
 "crm.customerId": "12345"
 }
 }
};

If I remember correctly, the root cause is often the SDK stripping unprefixed keys during the initial handshake validation, so nesting under guest.attributes with a dot-notation prefix ensures the payload survives the schema check. I have seen this pattern resolve similar data loss issues in custom dashboard integrations where attribute persistence is critical.

5

Ah, yeah, this is a known issue… The previous answers regarding guest.attributes are correct for the frontend SDK, but they miss the backend validation layer. If you are correlating this ID for analytics, simply passing it in startChat is not enough. You must ensure the attribute is defined as a custom conversation attribute in Genesys Cloud, or the platform will strip it during the conversation creation webhook.

I encountered this exact serialization loss while building my .NET reporting dashboard. Here is the verification flow:

  1. Define the custom attribute in the Platform API first. Use PUT /api/v2/attributes/conversations to ensure crm.customerId exists in the schema.
  2. In your Web Messaging SDK, pass the attribute exactly as shown below. Note the strict casing.
  3. Verify persistence using the .NET SDK ConversationsApi to fetch the transcript.
using PureCloudPlatform.Client.V2.Client;

// 1. Verify the attribute exists in the schema
var attributesApi = new AttributesApi();
var convAttributes = await attributesApi.GetAttributeConversationsAsync();

// 2. Check if your custom key is registered
bool isRegistered = convAttributes.CustomAttributes.Any(a => a.Key == "crm.customerId");

if (!isRegistered)
{
 // 3. Create the attribute definition if missing
 var newAttr = new AttributeDefinition
 {
 Key = "crm.customerId",
 Type = AttributeDefinition.TypeEnum.String
 };
 await attributesApi.PostAttributeConversationAsync(newAttr);
}

If the attribute is not pre-registered, the backend API rejects it silently or strips it before storing. I wasted two days debugging why my dashboard showed null values. The SDK sends it, but the platform ignores it without the schema definition. Always validate the attribute existence before relying on it for downstream analytics.