Getting only one row in CSV after converting JSON object to CSV file in Python

Question

I am totally new to python and i need some help, I'm Getting only one row in CSV file after running this code, the json file is big and has nested arrays Any Suggestions,

blob_service_client = BlobServiceClient.from_connection_string(constr)
container_client = blob_service_client.get_container_client(container_name)
blob_client = container_client.get_blob_client(filename)
streamdownloader = blob_client.download_blob()
JsonObject = json.loads(streamdownloader.readall())    

def get_leaves(item, key=None):
        if isinstance(item, dict):
            leaves = {}
            for i in item.keys():
                leaves.update(get_leaves(item[i], i))
            return leaves
        elif isinstance(item, list):
            leaves = {}
            for i in item:
                leaves.update(get_leaves(i, key))
            return leaves
        else:
            return {key : item}
    
    fieldnames = set()
    
    for entry in JsonObject:
        fieldnames.update(get_leaves(entry).keys())
    
        with open('C:/Users/Desktop/output.csv', 'w', newline='') as f_output:
            csv_output = csv.DictWriter(f_output, fieldnames=sorted(fieldnames))
            csv_output.writeheader()
            csv_output.writerows(get_leaves(entry) for entry in JsonObject)

Answer 1

You're opening the file inside loop, it is rewriting the file in each iteration, try this

with open('C:/Users/Desktop/output.csv', 'w', newline='') as f_output:
    csv_output = csv.DictWriter(f_output, fieldnames=sorted(fieldnames))
    csv_output.writeheader()
    for entry in JsonObject:
        fieldnames.update(get_leaves(entry).keys())
        csv_output.writerows(get_leaves(entry) for entry in JsonObject)