How To Convert JSON File To CSV Using Python Vice Versa

This example will tell you how to use python’s built-in json and csv modules to convert a CSV file to a JSON file, it also shows how to convert a JSON file to a CSV file.

python-convert-between-csv-and-json-file-example-source-files

The example files are listed in the above picture. I will explain them below.

  1. CSVJSONConvertionExample.py: This is the python source code file. There define a JsonCsvConverter class in it. This class has three methods, you can get each method explanation in the method comments.
  2. csv_user_info.csv:  This is the source CSV file, only this file exists at the beginning.
  3. json_user_info.json: This file is generated by the csv_2_json_by_reader or csv_2_json_by_dictreader method. The two methods read CSV data from the csv_user_info.csv file and convert the data to the python dictionary list object and then save the dict list object in this JSON file.
  4. The difference between the two methods is the first method reads the CSV file use csv.reader object, the second method read the CSV file use csv.DictReader object.
  5. new_csv_user_info.csv: This file is generated by the json_2_csv method.

1. CSVJSONConvertionExample.py

  1. CSVJSONConvertionExample.py
    '''
    @author: zhaosong
    '''
    import csv
    import os
    import json
    
    class JsonCsvConverter(object):
        
        # Convert a csv file content to a json file. Use csv.reader to read csv file data.
        def csv_2_json_by_reader(self, csv_file, json_file):
    
            # If the source csv_file exist.
            if(os.path.exists(csv_file)):
    
                # Open the csv file object with read permission.
                csv_file_object = open(csv_file, 'r')
    
                # Create a csv.reader object.
                csv_reader = csv.reader(csv_file_object)        
    
                # Save all csv file row data in a dictionary. Each row is another python dictionary.
                table_data_dict = {}
    
                # This list used to save csv field names.
                header_field_names_row = []
    
                # Save csv field names count.
                header_field_names_length = 0
    
                # Record the row number.
                row_number = 0            
    
                # Each row in the csv_reader is a list.
                for row in csv_reader:
    
                    # This is the header field row.
                    if(row_number==0):
                         header_field_names_row = row
                         header_field_names_length = len(row)
                    else:
                        # Save each row data in a dictionary.
                        row_data_dict = {}
    
                        # Loop the row get each column value and related field name.
                        for i in range(header_field_names_length):
                            # Get column field name.
                            field_name = header_field_names_row[i]
    
                            # Get column value.
                            field_value = row[i]
    
                            # Set column name and value in row_data_dict.
                            row_data_dict[field_name] = field_value
    
                        # Add the row dictionary object to the table dictionary object. 
                        table_data_dict[row_number] = row_data_dict
    
                    row_number += 1    
    
                # Open the json file with write permission.
                json_file_object = open(json_file, 'w')
    
                # Dump the table_data_dict to json file.    
                json.dump(table_data_dict, json_file_object)
    
                print("Convert " + csv_file + " to " + json_file + " success.")
            else:
                print(csv_file + " do not exist. ")   
    
    
        # Convert a csv file content to a json file. Use csv.DictReader to read csv file data.
        def csv_2_json_by_dictreader(self, csv_file, json_file):
    
            # If the source csv_file exist.
            if(os.path.exists(csv_file)):
                # Open the csv file object with read permission.
                csv_file_object = open(csv_file, 'r')
    
                # Create a csv.reader object.
                dict_csv_reader = csv.DictReader(csv_file_object, )            
    
                # Save all csv row data in a dictionary. Each row is another python dictionary.
                table_data_dict = {}
                
                # Record the row number.
                row_number = 1
    
                # Each row in the csv_reader is a dict list.
                for row in dict_csv_reader:
    
                    # Set row data in table_data_dict.
                    table_data_dict[row_number] = row
    
                    row_number += 1
                 
                # Open the json file with write permission.
                json_file_object = open(json_file, 'w')
    
                # Dump the table_data_dict to json file.    
                json.dump(table_data_dict, json_file_object)
    
                print("Convert " + csv_file + " to " + json_file + " success.")
            else:
                print(csv_file + " do not exist. ")           
        
    
        # Convert a json file content to a csv file.
        def json_2_csv(self, json_file, csv_file):
    
            # If the source json_file exist.
            if(os.path.exists(json_file)):
    
                # Get a file object with write permission.
                json_file_object = open(json_file, 'r')
    
                # Load JSON file data to a python dict object.
                table_dict = json.load(json_file_object)
    
                header_field_names_list = []
    
                # Convert the keys to a list. Otherwise when you call dict_keys[0] later, it will throw dict_keys do not support indexing error.
                dict_keys = list(table_dict.keys())
    
                dict_keys_length = len(dict_keys)
                
                if(dict_keys_length > 0):
                    # Get dict key.
                    dict_key = dict_keys[0]
    
                    # Get related value.
                    row_dict = table_dict[dict_key]
    
                    # Because the value is also a dictionary, so call it's keys() method to get a keys list, do not forget use list() to convert it to a pure list.
                    # This list will be used as the csv file headers field names.
                    header_field_names_list = list(row_dict.keys())
    
                # Open csv file with write permission.
                csv_file_object = open(csv_file, 'w')
    
                # Create a csv.DictWriter object with the target csv file and specified header field names list..
                csv_dict_file_writer = csv.DictWriter(csv_file_object, fieldnames=header_field_names_list)
    
                # Write csv file header field names.
                csv_dict_file_writer.writeheader()
    
                # Get rows dict list
                rows_dict_list = list(table_dict.values())
    
                # Loop in the row list.
                for row_dict in rows_dict_list:
                    # Write each row dict data to the csv file.
                    csv_dict_file_writer.writerow(row_dict)
                
                print("Convert " + json_file + " to " + csv_file + " success.")
            else:
                print(json_file + " do not exist. ")
    
    if __name__ == '__main__':
        converter = JsonCsvConverter()
        #converter.csv_2_json("./csv_user_info.csv", "./json_user_info.json")
        #converter.csv_2_json_by_dictreader("./csv_user_info.csv", "./json_user_info.json")
        converter.json_2_csv("./json_user_info.json", "./new_csv_user_info.csv")

2. csv_user_info.csv

  1. csv_user_info.csv
    'Name','Email','Title'
    'jerry','[email protected]','CEO'
    'tom','[email protected]','Developer'

3. json_user_info.json

  1. json_user_info.json
    {"1": {"'Name'": "'jerry'", "'Email'": "'[email protected]'", "'Title'": "'CEO'"}, "2": {"'Name'": "'tom'", "'Email'": "'[email protected]'", "'Title'": "'Developer'"}}

Reference

  1. Python Read/Write CSV File Example
  2. Python JSON Dump To Or Load From File Example
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