Stumbled on a weird bug today with a Data Action call to our FastAPI proxy. The response is 200 OK with valid JSON, but the success output variable is undefined.
{"status": "active", "agent_id": "123"}
Mapping $.agent_id works, but $.status fails. Is there a known issue with string values in the JSON extractor?
Can anyone share a working example of extracting nested string fields?
The simplest way to resolve this is to verify the JSON schema definition in your External Data Action. Genesys Cloud’s JSON extractor is strict about type matching, and sometimes implicit string inference fails if the schema isn’t explicitly defined as string. I hit this exact issue with my Deno Deploy webhooks when the payload shape shifted slightly. Ensure your schema explicitly declares "type": "string" for the status field.
Here is a minimal repro of the schema structure that works reliably for nested string fields. If you are using the API to define this action, make sure the schema property matches this structure exactly. The extractor needs to know the expected type before it attempts to parse the response body.
{
"type": "object",
"properties": {
"status": {
"type": "string"
},
"agent_id": {
"type": "string"
}
},
"required": ["status", "agent_id"]
}
If your schema is already correct and you are still seeing undefined, check the raw response headers. Sometimes the Content-Type header includes charset parameters like charset=utf-8 which can confuse the extractor if not handled properly. You can test this by adding a simple Set Header block after your HTTP request to force application/json without extra parameters. Also, ensure there is no leading whitespace or BOM in the JSON response body, as the parser is sensitive to that. I usually add a quick trim in my edge function before returning the JSON to avoid these edge cases.
It depends, but generally… The issue is rarely the JSON extractor itself, but rather how the FastAPI endpoint serializes the response before it reaches the Genesys Cloud Data Action. The documentation states: “The response body must be valid JSON with a Content-Type of application/json.” If your Flask or FastAPI app returns text/html or omits the header, the parser fails silently on complex types.
I debugged this by adding explicit headers in my Python microservice. Here is the working configuration:
from fastapi import FastAPI
from fastapi.responses import JSONResponse
app = FastAPI()
@app.get("/agent-status")
def get_status():
data = {"status": "active", "agent_id": "123"}
# Explicitly return JSONResponse to ensure correct headers
return JSONResponse(content=data, media_type="application/json")
Also, verify that the status field in your External Data Action schema is defined as string, not boolean or integer. Implicit type coercion often breaks here. See KB-9921 for details on strict schema enforcement in Data Actions.
You need to verify the Content-Type header in your FastAPI response. The extractor fails silently if it isn’t strictly application/json.
return JSONResponse(content={"status": "active", "agent_id": "123"})
Also, ensure the JSON schema in Architect explicitly defines status as a string. Implicit typing often breaks promotion pipelines when environments drift.
This is caused by strict Content-Type validation in the Genesys Cloud JSON extractor. The suggestion above is correct. Ensure your FastAPI endpoint returns application/json. I hit this when building Python ETL pipelines for analytics data. See KB-9981 for schema details.