The JSON Schema is here:
https://www.encodeproject.org/profiles/experiment#raw

I'm calling:
datamodel-codegen --input experiment.json --input-file-type jsonschema --output models/experiment.py --output-model-type pydantic_v2.BaseModel

The model is loaded perfectly by pydantic, but my specific data fails to validate:

$ python validate.py 
Validation failed!
165 validation errors for Experiment
biosample_ontology
  Input should be a valid string [type=string_type, input_value={'status': 'released', 's... 'K-562', 'K-562 cell']}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.4/v/string_type
analyses.0
  Input should be a valid string [type=string_type, input_value={'documents': ['/document...'ENCODE4 v1.2.1 GRCh38'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.4/v/string_type
analyses.1
  Input should be a valid string [type=string_type, input_value={'documents': ['/document...ENCODE4 v1.15.0 GRCh38'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.4/v/string_type
...

Here is the code of my simple validator script:

import json
from pydantic import ValidationError

from models.experiment import Experiment

def validate_json(json_data):
    try:
        Experiment(**json_data)
        print("Validation successful!")
    except ValidationError as e:
        print("Validation failed!")
        print(e)

if __name__ == "__main__":
    # Load JSON data to be validated
    with open('experiment-ENCSR545YBD.json', 'r') as f:
        data_json = json.load(f)
    
    # Validate
    validate_json(data_json)

The experiment JSON can be downloaded here:
https://www.encodeproject.org/experiments/ENCSR545YBD/?format=json

I guess it's to do with the complex data types not being strings, and being represented as $refs, but I don't know what I@m doing 😅