Invalid JSON: Unexpected type for Value message when passing tuples in json_data

[taavi-primer]

Seems SeldonClient is not able to encode tuples when they are passed in through json_data parameter. It is also unclear how to make use of the str_data and data input parameters (those could use documentation).

Small example:

import json
from seldon_core.seldon_client import SeldonClient

seldon_client = SeldonClient(
    gateway="istio",
    transport="rest",
    namespace="ml-serving",
    deployment_name="our-model",
    gateway_endpoint="our-istiogw",
)

example1 = ["Some text here.", "SomeName", [(0, 5)], [(10, 15)]]
example2 = json.loads(json.dumps(example1)) 

try:
    resp = seldon_client.predict(json_data=list([example1]), http_path="/api/v0.1/predictions")
    print(f"Response with example1: {resp.response.data.tensor}")
except Exception as ex:
    print(f"Exception thrown: {str(ex.message)}")

resp = seldon_client.predict(json_data=list([example2]), http_path="/api/v0.1/predictions")
print(f"Response with example2: {resp.response.data.tensor}")

Output from that is:

$ python ~/seldon_example1.py
Exception thrown: Invalid JSON: Unexpected type for Value message.
Response with example2: shape: 1
values: 0.006200790667543826

[ukclivecox]

Example1 is not valid JSON. The json module probably handles tuple automatically.

[taavi-primer]

How could it be? JSON is a string serialization of an object. Isn't the whole point of the json_data parameter to give it a Python object that needs to be serialized into a string? Or is the expected payload here already JSON-serialized? I don't think the latter works...

[ukclivecox]

The seldon client parses a json method first into a protoBuffer using:

seldon-core/python/seldon_core/utils.py

Line 48 in 574ac86

json_format.ParseDict(message_json, message_proto)

So the issue if that it fails at that point due to protoBuffers understanding of what is valid json and a tuple is not valid json.