ASP.NET Core Library – CsvHelper

前言

平常都是用 Excel 的多, 但这一次遇到 Google Ads. 谷歌嘛, 当然不喜欢微软的 Excel.

硬是要求 CSV. 没办法, 只能找 Library 搞一搞了.

参考

Docs – Getting Started

介绍

CsvHelper 只能简单的读写 CSV file, 接口也很少. 它最好的使用方式是一个 CSV file 对应一个 List<Item>.

它甚至不能像 Excel 那样, 选择某个 cell 直接修改. 只能 replace all.

安装

dotnet add package CsvHelper

Read CSV

首先定义 DataClass

和 Mapping logic

public class OfflineConversionData
{
    // format refer: https://support.google.com/google-ads/answer/7014069#prepare_data
    public string GoogleClickId { get; set; } = "";
    public string ConversionName { get; set; } = "";
    public string ConversionTime { get; set; } = "";
    public decimal ConversionValue { get; set; }
    public string ConversionCurrency { get; set; } = "";
}
public sealed class OfflineConversionDataMap : ClassMap<OfflineConversionData>
{
    public OfflineConversionDataMap()
    {
        Map(e => e.GoogleClickId).Name("Google Click ID").Index(0);
        Map(e => e.ConversionName).Name("Conversion Name").Index(1);
        Map(e => e.ConversionTime).Name("Conversion Time").Index(2);
        Map(e => e.ConversionValue).Name("Conversion Value").Index(3);
        Map(e => e.ConversionCurrency).Name("Conversion Currency").Index(4);
    }
}

然后

var rootPath = webHostEnvironment.WebRootPath;
var csvFilePath = Path.Combine(rootPath, "google-offline-conversion.csv");
using var streamReader = new StreamReader(csvFilePath);
using var csvReader = new CsvReader(streamReader, CultureInfo.InvariantCulture);
csvReader.Context.RegisterClassMap<OfflineConversionDataMap>();
var datas = csvReader.GetRecords<OfflineConversionData>();

read to DataTable

var rootPath = webHostEnvironment.WebRootPath;
var csvFilePath = Path.Combine(rootPath, "google-offline-conversion.csv");
using var streamReader = new StreamReader(csvFilePath);
using var csvReader = new CsvReader(streamReader, CultureInfo.InvariantCulture);
using var dataReader = new CsvDataReader(csvReader);
var table = new DataTable();
table.Load(dataReader);
var value = table.Rows[0][0].ToString(); // data only no header

Write CSV

using var memoryStream = new MemoryStream();
using var streamWriter = new StreamWriter(memoryStream);
using var csvWriter = new CsvWriter(streamWriter, CultureInfo.InvariantCulture);
csvWriter.Context.RegisterClassMap<OfflineConversionDataMap>();

var conversionDatas = new List<OfflineConversionData> {
    new OfflineConversionData {
        GoogleClickId = "EAIaIQobChMI9dfq693m_QIVRAQrCh3XcAANEAAYAyAAEgJJgPD_BwE",
        ConversionName = "Test Offline Conversion",
        ConversionTime = "2023-03-19 08:28:41 America/Los_Angeles",
        ConversionValue = 230,
        ConversionCurrency = "SGD",
    },
    new OfflineConversionData {
        GoogleClickId = "CjwKCAjwq-WgBhBMEiwAzKSH6C7RiEiGFcxvUAr6GEMhGPcYyWSOSo5eiiD_rzedifklbBVhKO4fVBoCUH8QAvD_BwE",
        ConversionName = "Test Offline Conversion",
        ConversionTime = "2023-03-22 11:09:01 Asia/Singapore",
        ConversionValue = 250,
        ConversionCurrency = "SGD",
    }
};
await csvWriter.WriteRecordsAsync<OfflineConversionData>(conversionDatas);
await csvWriter.FlushAsync();

var rootPath = webHostEnvironment.WebRootPath;
var csvFilePath = Path.Combine(rootPath, "google-offline-conversion.csv");
using var fileStream = System.IO.File.Create(csvFilePath);
await fileStream.WriteAsync(memoryStream.ToArray());
await fileStream.FlushAsync();

其它写入

csvWriter.WriteField("Hello World"); // first cell
csvWriter.NextRecord(); // next row
csvWriter.WriteField("Hello World 2"); // first cell