C#使用csvhelper实现csv的操作

新建控制台项目

安装csvhelper 33.0.1
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写入csv

新建Foo.cs

namespace CsvSut02;public class Foo
{public int Id { get; set; }public string Name { get; set; }
}

批量写入

using System.Globalization;
using CsvHelper;
using CsvHelper.Configuration;namespace CsvSut02;class Program
{static void Main(string[] args){List<Foo> foos = new List<Foo>();for (int i = 0; i < 100; i++){foos.Add(new Foo(){Id = i,Name = "我是" + i});}var fileName = $"{DateTime.Now.ToString("yyyy_MM_dd_HH_mm_ss")}.csv";using (var writer = new StreamWriter(fileName)){var config = new CsvConfiguration(CultureInfo.InvariantCulture);using (var csv = new CsvWriter(writer, config)){csv.WriteRecords(foos);}}}
}

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逐条写入

using System.Globalization;
using CsvHelper;
using CsvHelper.Configuration;namespace CsvSut02;class Program
{static void Main(string[] args){List<Foo> foos = new List<Foo>();for (int i = 0; i < 100; i++){foos.Add(new Foo(){Id = i,Name = "我是" + i});}var fileName = $"{DateTime.Now.ToString("yyyy_MM_dd_HH_mm_ss")}.csv";using (var writer = new StreamWriter(fileName)){var config = new CsvConfiguration(CultureInfo.InvariantCulture);using (var csv = new CsvWriter(writer, config)){//这里看过来foreach (var foo in foos){csv.WriteRecord(foo);csv.NextRecord();}}}}
}

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增加标题

特性方式

using CsvHelper.Configuration.Attributes;namespace CsvSut02;public class Foo
{[Name("Id")]public int Id { get; set; }[Name("Name")]public string Name { get; set; }
}using System.Globalization;
using CsvHelper;
using CsvHelper.Configuration;namespace CsvSut02;class Program
{static void Main(string[] args){List<Foo> foos = new List<Foo>();for (int i = 0; i < 100; i++){foos.Add(new Foo(){Id = i,Name = "我是" + i});}var fileName = $"{DateTime.Now.ToString("yyyy_MM_dd_HH_mm_ss")}.csv";using (var writer = new StreamWriter(fileName)){var config = new CsvConfiguration(CultureInfo.InvariantCulture);using (var csv = new CsvWriter(writer, config)){csv.WriteHeader<Foo>();csv.NextRecord(); foreach (var foo in foos){csv.WriteRecord(foo);csv.NextRecord();}}}}
}

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配置类

新建FooClassMap.cs

using CsvHelper.Configuration;namespace CsvSut02;public class FooClassMap : ClassMap<Foo>
{public FooClassMap(){Map(m => m.Id).Index(0).Name("id");Map(m => m.Name).Index(1).Name("name");}
}

修改Program.cs

using System.Globalization;
using CsvHelper;
using CsvHelper.Configuration;namespace CsvSut02;class Program
{static void Main(string[] args){List<Foo> foos = new List<Foo>();for (int i = 0; i < 100; i++){foos.Add(new Foo(){Id = i,Name = "我是" + i});}var fileName = $"{DateTime.Now.ToString("yyyy_MM_dd_HH_mm_ss")}.csv";using (var writer = new StreamWriter(fileName)){var config = new CsvConfiguration(CultureInfo.InvariantCulture);using (var csv = new CsvWriter(writer, config)){csv.Context.RegisterClassMap<FooClassMap>();csv.WriteHeader<Foo>();csv.NextRecord();foreach (var foo in foos){csv.WriteRecord(foo);csv.NextRecord();}}}}
}

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可能有人觉得麻烦，使用配置类可以保证原始类的纯粹，保证poco

读取csv

读取和写入一样，可以两种方式实现一个是配置类一个是特性，下面都以特性演示

无标题csv

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using CsvHelper.Configuration.Attributes;namespace CsvSut02;public class Foo
{[Index(0)]public int Id { get; set; }[Index(1)]public string Name { get; set; }
}using System.Globalization;
using CsvHelper;
using CsvHelper.Configuration;namespace CsvSut02;class Program
{static void Main(string[] args){var file = "2024_07_24_18_24_00.csv";using (var reader = new StreamReader(file)){var config = new CsvConfiguration(CultureInfo.InvariantCulture);config.HasHeaderRecord = false;//没有头部using (var csv = new CsvReader(reader, config)){var records = csv.GetRecords<Foo>().ToList();foreach (var record in records){Console.WriteLine(record.Id);   }}}}
}

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有标题csv

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using CsvHelper.Configuration.Attributes;namespace CsvSut02;public class Foo
{[Name("id")]public int Id { get; set; }[Name("name")]public string Name { get; set; }
}using CsvHelper.Configuration.Attributes;namespace CsvSut02;public class Foo
{[Name("id")]public int Id { get; set; }[Name("name")]public string Name { get; set; }
}using System.Globalization;
using CsvHelper;
using CsvHelper.Configuration;namespace CsvSut02;class Program
{static void Main(string[] args){var file = "2024_07_24_18_30_49.csv";using (var reader = new StreamReader(file)){var config = new CsvConfiguration(CultureInfo.InvariantCulture);config.HasHeaderRecord = true;//有头部using (var csv = new CsvReader(reader, config)){var records = csv.GetRecords<Foo>().ToList();foreach (var record in records){Console.WriteLine(record.Id);   }}}}
}

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增量写入

using System.Globalization;
using System.Text;
using CsvHelper;
using CsvHelper.Configuration;namespace CsvSut02;class Program
{static void Main(string[] args){var fileName = $"{DateTime.Now.ToString("yyyy_MM_dd_HH_mm_ss")}.csv";WriteModelWithAppend(fileName);WriteModelWithAppend(fileName);}/// <summary>/// 追加方式写入/// </summary>/// <param name="fileName"></param>static void WriteModelWithAppend(string fileName){var model = new Foo();model.Id = 1;model.Name = "测试";// 检查文件是否存在，以确定是否应该以追加模式打开  var mode = File.Exists(fileName) ? FileMode.Append : FileMode.Create;var config = new CsvConfiguration(CultureInfo.InvariantCulture);using var writer = new StreamWriter(new FileStream(fileName, mode, FileAccess.Write, FileShare.Read),Encoding.UTF8);using var csv = new CsvWriter(writer, config);if (mode == FileMode.Create){csv.WriteHeader<Foo>();csv.NextRecord(); }csv.WriteRecord(model);csv.NextRecord(); }
}