using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Runtime.Serialization.Formatters;

using System.IO;

using System.Data;

using System.ComponentModel.DataAnnotations;

using System.Globalization;

using System.Reflection;

using System.Collections.ObjectModel;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;    

​

using CsvHelper;

using CsvHelper.Configuration;

using CsvHelper.Configuration.Attributes;

using CsvHelper.Expressions;

using CsvHelper.TypeConversion;

​

using NUnit.Framework; // Throws NUnit.Framework.AssertionException

​

​

​

//https://stackoverflow.com/questions/73377519/how-do-you-create-a-data-table-from-json-in-c-sharp-visual-basic

​

    public static partial class JsonExtensions

    {

        public static IEnumerable<IEnumerable<KeyValuePair<string, JValue>>> FlattenChildrenIntoRows(this JObject obj)

        {

            bool anyReturned = false;

            var simpleChildren = obj.Properties().Where(p => p.Value is JValue).Select(p => new KeyValuePair<string, JValue>(p.Name, (JValue)p.Value)).ToList();

            var complexChildren = obj.Properties().Where(p => !(p.Value is JValue)).Select(p => new KeyValuePair<string, JToken>(p.Name, p.Value));

            foreach (var property in complexChildren)

            {

                foreach (var flattenedItems in FlattenChildrenIntoRows(property))

                {

                    yield return simpleChildren.Concat(flattenedItems);

                    anyReturned = true;

                }

            }

​

            if (!anyReturned)

                yield return simpleChildren;

        }

​

        static IEnumerable<IEnumerable<KeyValuePair<string, JValue>>> FlattenChildrenIntoRows(KeyValuePair<string, JToken> property) 

        {

            if (property.Value is JValue value)

            {

                yield return new[] { new KeyValuePair<string, JValue>(property.Key, value) };

            }

            else if (property.Value is JArray array)

            {

                foreach (var item in array)

                    foreach (var flattenedItem in FlattenChildrenIntoRows(new KeyValuePair<string, JToken>(property.Key, item)))

                        yield return flattenedItem;

            }

            else if (property.Value is JObject obj)

            {

                foreach (var flattenedItems in FlattenChildrenIntoRows(obj))

                    yield return flattenedItems.Select(p => new KeyValuePair<string, JValue>(property.Key + "." + p.Key, p.Value));

            }

            else // JRaw, JContainer

            {

                throw new NotImplementedException();

            }

        }

    }

​

    public static partial class CsvExtensions

    {

        public static void WriteCsv(TextWriter writer, IReadOnlyList<IDictionary<string, string>> objects, CsvConfiguration config)

        {

            var headers = objects.SelectMany(o => o.Keys).Distinct();

            using (var csv = new CsvWriter(writer, config))

            {

                foreach (var header in headers)

                    csv.WriteField(header);

                csv.NextRecord();

                foreach (var obj in objects)

                {

                    foreach (var header in headers)

                        if (obj.TryGetValue(header, out var value))

                            csv.WriteField(value);

                        else

                            csv.WriteField(null);

                    csv.NextRecord();

                }

            }           

        }

    }

​

    public static partial class CsvExtensions

    {

        /// Convert a JSON file to a CSV file

        public static void ConvertJsonToCsv(string inputPath, string outputPath)

        {

            using var reader = new StreamReader(inputPath);

            using var writer = new StreamWriter(outputPath);

            ConvertJsonToCsv(reader, writer);

        }

        /// Read JSON from the incoming TextReader, convert to CSV and write to the incoming TextWriter

        public static void ConvertJsonToCsv(TextReader reader, TextWriter writer)

        {

            // Disable reformatting of dates

            var settings = new JsonSerializerSettings

            {

                DateParseHandling = DateParseHandling.None,

            };

            using var jsonReader = new JsonTextReader(reader) { CloseInput = false };

            // Deserialize to an array of objects

            var array = JsonSerializer.CreateDefault(settings).Deserialize<List<JObject>>(jsonReader);

            // Flatten and convert to a List<Dictionary<string, string>>

            var list = array

                // Flatten each child into an enumerable of enumerable of primitive key/value pairs

                .Select(o => o.FlattenChildrenIntoRows())

                // Project and flatten to an overall enumerable of enumerable of pairs

                .SelectMany(pairs => pairs)

                // Convert to an overall enumerable of dictionaries

                .Select(pairs => pairs.ToDictionary(p => p.Key, p => p.Value.Value == null ? null : (string)Convert.ChangeType(p.Value.Value, typeof(string), CultureInfo.InvariantCulture)))

                // Materialize as a list of dictionaries

                .ToList();

            // Write to CSV

            var config = new CsvConfiguration(CultureInfo.InvariantCulture);

            CsvExtensions.WriteCsv(writer, list, config);

        }

    }

​

    class TestClass

    {

        public static void Test()

        {

            var jsonString = GetJson();

​

            var response = new

            {

                Content = jsonString,

            };

            using var reader = new StringReader(response.Content);

            using var writer = new StringWriter();

            CsvExtensions.ConvertJsonToCsv(reader, writer);

            var csvText = writer.ToString();

            Console.WriteLine(csvText);

        }   

        static string GetJson() { return @"[

{

    ""transaction_id"": ""00000352"",

    ""transaction_type"": ""New"",

    ""transaction_date"": ""2018-08-23T00:00:00"",

    ""sold_to_id"": ""00026"",

    ""customer_po_number"": ""34567"",

    ""po_date"": ""2018-08-23T00:00:00"",

    ""notes"": null,

    ""batch_code"": ""######"",

    ""location_id"": ""MN"",

    ""req_ship_date"": ""2018-08-28T00:00:00"",

    ""fiscal_period"": 8,

    ""fiscal_year"": 2018,

    ""currency_id"": ""USD"",

    ""original_invoice_number"": null,

    ""bill_to_id"": ""00026"",

    ""customer_level"": null,

    ""terms_code"": ""30-2"",

    ""distribution_code"": ""01"",

    ""invoice_number"": null,

    ""invoice_date"": ""2018-08-23T00:00:00"",

    ""sales_rep_id_1"": null,

    ""sales_rep_id_1_percent"": 100,

    ""sales_rep_id_1_rate"": 0,

    ""sales_rep_id_2_id"": ""SA"",

    ""sales_rep_id_2_percent"": 100,

    ""sales_rep_id_2_rate"": 10,

    ""ship_to_id"": null,

    ""ship_via"": null,

    ""ship_method"": null,

    ""ship_number"": null,

    ""ship_to_name"": """",

    ""ship_to_attention"": null,

    ""ship_to_address_1"": null,

    ""ship_to_address_2"": null,

    ""ship_to_city"": null,

    ""ship_to_region"": null,

    ""ship_to_country"": ""USA"",

    ""ship_to_postal_code"": null,

    ""actual_ship_date"": null,

    ""order_line_list"": [

        {

            ""entry_number"": 1,

            ""item_id"": ""5' Glass/Wood Table"",

            ""description"": ""Glass/ Wood Combo Coffee Table"",

            ""customer_part_no"": null,

            ""additional_description"": null,

            ""location_id"": ""MN"",

            ""quantity_ordered"": 11,

            ""units"": ""EA"",

            ""quantity_shipped"": 0,

            ""quantity_backordered"": 0,

            ""req_ship_date"": null,

            ""unit_price"": 599.99,

            ""extended_price"": 6599.89,

            ""reason_code"": null,

            ""account_code"": null,

            ""inventory_gl_account"": ""120000"",

            ""sales_gl_account"": ""400000"",

            ""cogs_gl_account"": ""500000"",

            ""sales_category"": null,

            ""tax_class"": 0,

            ""promo_id"": null,

            ""price_id"": null,

            ""discount_type"": 0,

            ""discount_percentage"": 0,

            ""discount_amount"": 0,

            ""sales_rep_id_1"": null,

            ""sales_rep1_percent"": null,

            ""sales_rep1_rate"": null,

            ""sales_rep_id_2"": ""SA"",

            ""sales_rep2_percent"": 100,

            ""sales_rep2_rate"": 5,

            ""unit_cost"": 241.4467,

            ""extended_cost"": 2655.91,

            ""status"": ""Open"",

            ""extended_list"": [""yo""],

            ""serial_list"": []

        },

        {

            ""entry_number"": 2,

            ""item_id"": ""6' Glass/Wood Table"",

            ""description"": ""Glass/ Wood Combo Coffee Table"",

            ""customer_part_no"": null,

            ""additional_description"": null,

            ""location_id"": ""MN"",

            ""quantity_ordered"": 11,

            ""units"": ""EA"",

            ""quantity_shipped"": 0,

            ""quantity_backordered"": 0,

            ""req_ship_date"": null,

            ""unit_price"": 599.99,

            ""extended_price"": 6599.89,

            ""reason_code"": null,

            ""account_code"": null,

            ""inventory_gl_account"": ""120000"",

            ""sales_gl_account"": ""400000"",

            ""cogs_gl_account"": ""500000"",

            ""sales_category"": null,

            ""tax_class"": 0,

            ""promo_id"": null,

            ""price_id"": null,

            ""discount_type"": 0,

            ""discount_percentage"": 0,

            ""discount_amount"": 0,

            ""sales_rep_id_1"": null,

            ""sales_rep1_percent"": null,

            ""sales_rep1_rate"": null,

            ""sales_rep_id_2"": ""SA"",

            ""sales_rep2_percent"": 100,

            ""sales_rep2_rate"": 5,

            ""unit_cost"": 241.4467,

            ""extended_cost"": 2655.91,

            ""status"": ""Open"",

            ""extended_list"": [],

            ""serial_list"": []

        }

    ],

    ""tax_group_id"": ""ATL"",

    ""taxable"": false,

    ""tax_class_adjustment"": 0,

    ""freight"": 0,

    ""tax_class_freight"": 0,

    ""tax_location_adjustment"": null,

    ""misc"": 0,

    ""tax_class_misc"": 0,

    ""sales_tax"": 0,

    ""taxable_sales"": 0,

    ""non_taxable_sales"": 6599.89,

    ""payment_list"": []

}

​

]

"; 

                                }

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: {0} ({1})", System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , Environment.Version);

            Console.WriteLine("{0} version: {1}", typeof(JsonSerializer).Assembly.GetName().Name,  typeof(JsonSerializer).Assembly.FullName);

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

                Console.WriteLine("Failed with unhandled exception: ");

                Console.WriteLine(ex);

                throw;

            }

        }

    }

​