I’m developing a Flask application and encountering a TypeError when trying to save entities to Google Cloud Datastore. I am on a mac, Montery. I have google-cloud-datastore-2.19.0 and protobuf-4.23.2. I am using python-3.9.12. I got this error,
TypeError: Parameter to MergeFrom() must be instance of same class: expected google.datastore.v1.Key.PathElement got PathElement.
I searched StackOverflow and found 1 person who solved it by downgrading protobuf. It did not work for me. I checked my code and I am calling the functions correctly.
I would appreciate any advice on how to deal with this error.
save_story_to_datastore(story_content)
def save_story_to_datastore(story_content):
"""
Saves a new story to Google Cloud Datastore.
"""
client = get_datastore_client()
key = client.key('Story')
entity = datastore.Entity(key=key)
entity.update({
'story_text': story_content,
'created_at': datetime.datetime.utcnow()
})
client.put(entity)
def get_datastore_client():
"""
Creates and returns a Google Cloud Datastore client configured with a service account.
"""
try:
# Fetch the service account key JSON from Secret Manager
sa_key_json = get_secret('content-genie-network-sa-key')
# Load the JSON string into a dictionary
sa_key = json.loads(sa_key_json)
# Construct the credentials object from the service account key
credentials = service_account.Credentials.from_service_account_info(sa_key)
# Create a Datastore client using the credentials
client = datastore.Client(credentials=credentials)
return client
except json.JSONDecodeError:
raise ValueError("Failed to decode the JSON key for the service account.")
except DefaultCredentialsError as e:
raise RuntimeError(f"Failed to create credentials with the provided key: {e}")
except Exception as e:
raise RuntimeError(f"An error occurred while setting up the Datastore client: {e}")
The TypeError: Parameter to MergeFrom() must be instance of same class: expected google.datastore.v1.Key.PathElement got PathElement indicates a type mismatch. The MergeFrom() method (used internally by the library) expects a google.datastore.v1.Key.PathElement object, but it’s receiving a plain PathElement. This often stems from:
Version Incompatibility: Mismatched versions of google-cloud-datastore and protobuf libraries.
Incorrect Imports/Usage: Directly using PathElement instead of google.datastore.v1.Key.PathElement or manipulating low-level Protobuf objects.
Solutions:
Resolve Version Conflicts:
Check Compatibility: Consult the official documentation or release notes for google-cloud-datastore to identify the compatible protobuf version range.
Use Virtual Environments: Isolate project dependencies to avoid conflicts:
# Using virtualenv:
python -m venv env
source env/bin/activate
pip install google-cloud-datastore protobuf
# Using conda:
conda create -n myenv python=3.9 # Replace 3.9 with your desired version
conda activate myenv
conda install -c conda-forge google-cloud-datastore protobuf
Ensure Correct Imports and Usage:
Import PathElement Correctly:
from google.datastore.v1.key_pb2 import PathElement
Follow Datastore API Best Practices: Stick to the high-level API provided by google-cloud-datastore for database operations. Refer to the official documentation https://cloud.google.com/datastore for recommended usage.
Additional Tips:
Logging: Add detailed logging using logging.basicConfig(level=logging.DEBUG) to capture context in case of errors.
Separate Testing: Isolate the problematic code using unit tests with mocked Datastore responses.
Please forgive me for taking so long to get back to you. Although it took a long time to reply I truly appreciate the responses. I could not get it to work so I switched to Firestore.
