Runpod’s validator utility ensures robust execution of serverless workers by validating input data against a defined schema. To use it, import the following to your Python file: 
from runpod.serverless.utils.rp_validator import validate
The validate function takes two arguments:
  • the input data
  • the schema to validate against

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Schema Definition

Define your schema as a nested dictionary with these possible rules for each input:
  • required (default: False): Marks the type as required.
  • default (default: None): Default value if input is not provided.
  • type (required): Expected input type.
  • constraints (optional): for example, a lambda function returning true or false.

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Example Usage

import runpod
from runpod.serverless.utils.rp_validator import validate

schema = {
    "text": {
        "type": str,
        "required": True,
    },
    "max_length": {
        "type": int,
        "required": False,
        "default": 100,
        "constraints": lambda x: x > 0,
    },
}


def handler(event):
    try:
        validated_input = validate(event["input"], schema)
        if "errors" in validated_input:
            return {"error": validated_input["errors"]}

        text = validated_input["validated_input"]["text"]
        max_length = validated_input["validated_input"]["max_length"]

        result = text[:max_length]
        return {"output": result}
    except Exception as e:
        return {"error": str(e)}


runpod.serverless.start({"handler": handler})

​
Testing

Save as your_handler.py and test using: 
python your_handler.py
Or with inline input:
python your_handler.py --test_input '{"input": {"text": "Hello, world!", "max_length": 5}}'
This approach allows early detection of input errors, preventing issues from unexpected or malformed inputs.