Count columns of a dynamic frame, AWS Glue Pyspark

count_fields.py

from awsglue.dynamicframe import DynamicFrame
from pyspark.context import SparkContext
from awsglue.context import GlueContext

glueContext = GlueContext(SparkContext.getOrCreate())
datasource0 = glueContext.create_dynamic_frame.from_catalog(database='my database', table_name='my_table')

#Assuming <datasource0> is an object of the class <class 'awsglue.dynamicframe.DynamicFrame'>
columns_count = len(datasource0.schema().__dict__['fields']))
print('fields: {}'.format(columns_count))

#stdout:
#fields: 18203