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import csv
import io
import boto3
import os
from typing import List, Dict
from .logger import get_logger
from .utils import Utilities
class DataReader:
"""
A class to read CSV data from a local file, S3 object, or string. Near
the project completion, support for JSON/Parquet files will be added.
"""
def __init__(self, log_level=None):
self.log_level = log_level
self.logger = get_logger("CSVREADER", log_level)
def read_local(self, path) -> List[Dict[str, str]]:
"""
A method to read a local CSV file and return the data as a list of
dictionaries.
"""
self.logger.debug(f"Reading local CSV from: {path}")
try:
with open(path, mode="r", encoding="utf-8") as f:
reader = csv.DictReader(f)
return [dict(row) for row in reader]
except FileNotFoundError:
self.logger.error(f"File not found: {path}")
raise
except Exception as e:
self.logger.error(f"Error reading file: {e}")
def read_s3(self, path) -> List[Dict[str, str]]:
"""
A method to read an S3 object containing CSV data
and return the data as a list of dictionaries.
"""
utils = Utilities(self.log_level)
bucket, key = utils.get_s3_path(path)
self.logger.debug(f"Reading S3 CSV from: {bucket}/{key}")
client = boto3.client("s3")
try:
response = client.get_object(Bucket=bucket, Key=key)
self.logger.info("S3 object read successfully")
content = response["Body"].read().decode("utf-8")
read_csv_content = self.read_string(content)
return utils.create_byte_stream(read_csv_content)
except client.exceptions.NoSuchKey:
self.logger.error(f"Object not found: {bucket}/{key}")
raise
except client.exceptions.ClientError as e:
self.logger.error(f"Error reading S3 object: {e}")
raise
except UnicodeDecodeError as e:
self.logger.error(f"Error decoding S3 object: {e}")
raise
except Exception as e:
self.logger.error(f"Error reading S3 object: {e}")
raise
def read_string(self, content: str) -> List[Dict[str, str]]:
"""
A method to read CSV data from a string and return the data as a list
of dictionaries.
"""
if not content.strip():
return []
f = io.StringIO(content)
reader = csv.DictReader(f)
return [dict(row) for row in reader]
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