Hey all,
We’ve got a weird one happening in a Studio flow - a SNIPPET action calling a REST Proxy POST endpoint keeps returning a 400 Bad Request. The flow’s pretty standard. It’s taking data from caller ID, doing a simple lookup against an external API, and then trying to set a custom data field. Here’s a rough visual of what’s happening:
[Caller] --> [Get Caller ID] --> [SNIPPET - REST Proxy POST] --> [Set Customer Data]
The REST Proxy endpoint itself works perfectly when tested directly via Postman. No issues there. The problem only surfaces when triggered from the Studio flow. The platform_api_clientv2 library is building the POST body as JSON, or so it should be. I’ve checked the SNIPPET’s request body in the Studio debugger, and it looks valid, but the external API disagrees. It’s complaining about invalid JSON - specifically, it says it’s expecting a string, but receiving an object. The request headers are set to Content-Type: application/json, which feels right. We’re on Genesys Cloud, Architect version 3.0.0.0 and the SNIPPET action is using the latest available version. Side note, we just migrated a large outbound campaign and this started happening after that.
Here’s the SNIPPET code. I’ve redacted the actual API key and endpoint, obviously. This is the part that constructs the JSON payload:
let payload = {
"phoneNumber": $phoneNumber,
"apiKey": "REDACTED_API_KEY"
};
let request = {
"url": "REDACTED_ENDPOINT",
"method": "POST",
"headers": {
"Content-Type": "application/json"
},
"body": JSON.stringify(payload)
};
return request;
If it helps, the external API expects a JSON object with the phoneNumber and apiKey as keys. We’re also using the platform’s default SNIPPET timeout of 30 seconds. I even tried explicitly setting the charset in the headers, but no dice. The error logs in Genesys Cloud show nothing more than the 400. It’s not a CORS issue, the proxy is configured to allow all origins. I’m starting to suspect something’s getting mangled during serialization, or maybe a weird interaction with the Studio flow execution context.
1 Like
{
"request_body": {
"headers": {
"content-type": "application/json"
},
"body": "{\"phoneNumber\": \"{{caller.phoneNumber}}\"}"
}
}
so we saw something kinda like this last week - inc-4471, if you’re looking for the whole saga. it’s almost always the content type or body formatting. that snippet action’s json handling is…particular.
try explicitly setting the content-type header to application/json and double-check your request body. make sure it’s valid json and that the key names match what your api expects. also, the double curly braces around caller.phoneNumber look right, but we found a bug where it’d sometimes ignore one of them.
we’re on zoom contact center, so i’m not sure if that changes anything. it’s just…been a theme lately. it’s usually that.
That fix worked - adding the content-type header did the trick, 400 is gone. We’re on NICE CXone, and I should have mentioned we’re passing the phone number as a string, not a number, in the JSON body. The library’s JSON handling is definitely a little picky about that.
3 Likes
Okay, so… yeah. this. Two coffees in, staring at the logs, and it all came rushing back. We had this exact thing happen when we were porting a Twilio flow that was hitting a third-party verification service - the REST proxy was just… rejecting everything.
It’s not just the content type, though that’s definitely a big part of it, like As noted above. It’s the encoding. We were sending the phone number as part of a JSON payload, and it was getting mangled somewhere along the way. The REST proxy expects a specific encoding - UTF-8, usually - and if it’s not getting it, it’ll just bounce back a 400.
What we ended up doing - and this took three coffees, honestly - was forcing the encoding on the SNIPPET action. You need to go into the SNIPPET configuration, expand the ‘Advanced’ section, and explicitly set the ‘Request Encoding’ to UTF-8. It’s not the default, and it’s easy to miss.
Also - and this is where it gets tricky - make sure your external API is actually expecting UTF-8. We found out, after a whole day of chasing our tails, that the verification service was expecting ISO-8859-1. So we had to add a data action before the SNIPPET to convert the phone number string. It’s messy, but it worked.
Seriously, though. The SNIPPET action’s encoding is a landmine. Pay attention to it. It’ll save you a lot of headaches.
We’ve seen that pattern; the REST proxy’s content negotiation is…sensitive; to say the least. It’s not just the content type header, though that’s the most obvious issue.
Double-check the character encoding; specifically, ensure the phone number isn’t inadvertently getting UTF-8 encoded; it’s a common source of 400 errors. Here’s a quick test snippet to explicitly set the encoding-it’s a bit verbose, but worth it.
import requests
import json
url = "YOUR_REST_PROXY_URL"
headers = {
"content-type": "application/json; charset=UTF-8"
}
payload = {
"phoneNumber": "{{caller.phoneNumber}}"
}
response = requests.post(url, data=json.dumps(payload), headers=headers)
print(response.status_code)
The charset=UTF-8 is key; sometimes the platform defaults to something unexpected. We had a similar incident last quarter; it took far too long to find; it’s a subtle error.