MiniExcel/README.zh-Hant.md

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簡介

MiniExcel 簡單、高效避免OOM的.NET處理Excel工具。

目前主流框架大多需要將資料全載入到記憶體方便操作，但這會導致記憶體消耗問題，MiniExcel 嘗試以 Stream 角度寫底層算法邏輯，能讓原本1000多MB占用降低到幾MB，避免記憶體不夠情況。

特點

• 低記憶體耗用，避免OOM(out of memoery)、頻繁 Full GC 情況
• 支持即時操作每行資料
• 兼具搭配 LINQ 延遲查詢特性，能辦到低消耗、快速分頁等複雜查詢
  圖片:與主流框架對比的消耗、效率差
  
• 輕量，不依賴任何套件，DLL小於100KB
• 簡便操作的 Dapper API 風格

Demo

• LINQPad : Download Basic Demo.linq

安裝

請查看 from NuGet

更新日誌

請查看 Release Notes

Discussions / TODO

請查看 Discussions / TODO

性能測試

以 Test1,000,000x10.xlsx 做基準與主流框架做性能測試，總共 1千萬筆 "HelloWorld"，檔案大小 23 MB

Benchmarks 邏輯可以在 MiniExcel.Benchmarks 查看或是提交 PR，運行指令

dotnet run -p .\benchmarks\MiniExcel.Benchmarks\ -c Release -f netcoreapp3.1 -- -f * --join

最後一次運行結果 :

BenchmarkDotNet=v0.12.1, OS=Windows 10.0.19042
Intel Core i7-7700 CPU 3.60GHz (Kaby Lake), 1 CPU, 8 logical and 4 physical cores
  [Host]     : .NET Framework 4.8 (4.8.4341.0), X64 RyuJIT
  Job-ZYYABG : .NET Framework 4.8 (4.8.4341.0), X64 RyuJIT
IterationCount=3  LaunchCount=3  WarmupCount=3  

Method	最大記憶體耗用	平均時間	Gen 0	Gen 1	Gen 2
'MiniExcel QueryFirst'	0.109 MB	726.4 us	-	-	-
'ExcelDataReader QueryFirst'	15.24 MB	10,664,238.2 us	566000.0000	1000.0000	-
'MiniExcel Query'	17.3 MB	14,179,334.8 us	367000.0000	96000.0000	7000.0000
'ExcelDataReader Query'	17.3 MB	22,565,088.7 us	1210000.0000	2000.0000	-
'Epplus QueryFirst'	1,452 MB	18,198,015.4 us	535000.0000	132000.0000	9000.0000
'Epplus Query'	1,451 MB	23,647,471.1 us	1451000.0000	133000.0000	9000.0000
'OpenXmlSDK Query'	1,412 MB	52,003,270.1 us	978000.0000	353000.0000	11000.0000
'OpenXmlSDK QueryFirst'	1,413 MB	52,348,659.1 us	978000.0000	353000.0000	11000.0000
'ClosedXml QueryFirst'	2,158 MB	66,188,979.6 us	2156000.0000	575000.0000	9000.0000
'ClosedXml Query'	2,184 MB	191,434,126.6 us	2165000.0000	577000.0000	10000.0000

Method	最大記憶體耗用	平均時間	Gen 0	Gen 1	Gen 2
'MiniExcel Create Xlsx'	15 MB	11,531,819.8 us	1020000.0000	-	-
'Epplus Create Xlsx'	1,204 MB	22,509,717.7 us	1370000.0000	60000.0000	30000.0000
'OpenXmlSdk Create Xlsx'	2,621 MB	42,473,998.9 us	1370000.0000	460000.0000	50000.0000
'ClosedXml Create Xlsx'	7,141 MB	140,939,928.6 us	5520000.0000	1500000.0000	80000.0000

Query 查詢 Excel 返回強型別 IEnumerable 資料 [Try it]

推薦使用 Stream.Query 效率會相對較好。

public class UserAccount
{
    public Guid ID { get; set; }
    public string Name { get; set; }
    public DateTime BoD { get; set; }
    public int Age { get; set; }
    public bool VIP { get; set; }
    public decimal Points { get; set; }
}

var rows = MiniExcel.Query<UserAccount>(path);

// or

using (var stream = File.OpenRead(path))
    var rows = stream.Query<UserAccount>();

Query 查詢 Excel 返回Dynamic IEnumerable 資料 [Try it]

• Key 系統預設為 A,B,C,D...Z

MiniExcel	1
Github	2

var rows = MiniExcel.Query(path).ToList();

// or 
using (var stream = File.OpenRead(path))
{
    var rows = stream.Query().ToList();
                
    Assert.Equal("MiniExcel", rows[0].A);
    Assert.Equal(1, rows[0].B);
    Assert.Equal("Github", rows[1].A);
    Assert.Equal(2, rows[1].B);
}

查詢資料以第一行數據當Key [Try it]

note : 同名以右邊數據為準

Input Excel :

Column1	Column2
MiniExcel	1
Github	2

var rows = MiniExcel.Query(useHeaderRow:true).ToList();

// or

using (var stream = File.OpenRead(path))
{
    var rows = stream.Query(useHeaderRow:true).ToList();

    Assert.Equal("MiniExcel", rows[0].Column1);
    Assert.Equal(1, rows[0].Column2);
    Assert.Equal("Github", rows[1].Column1);
    Assert.Equal(2, rows[1].Column2);
}

Query 查詢支援延遲加載(Deferred Execution)，能配合LINQ First/Take/Skip辦到低消耗、高效率複雜查詢

Query First

var row = MiniExcel.Query(path).First();
Assert.Equal("HelloWorld", row.A);

// or

using (var stream = File.OpenRead(path))
{
    var row = stream.Query().First();
    Assert.Equal("HelloWorld", row.A);
}

建立 Excel 檔案 [Try it]

1. 必須是 non-abstract 類別有 public parameterless constructor
2. MiniExcel SaveAs 支援 IEnumerable參數``延遲查詢，除非必要請不要使用 ToList 等方法讀取全部資料到記憶體

圖片 : 是否呼叫 ToList 的記憶體差別

Anonymous or strongly type:

var path = Path.Combine(Path.GetTempPath(), $"{Guid.NewGuid()}.xlsx");
MiniExcel.SaveAs(path, new[] {
    new { Column1 = "MiniExcel", Column2 = 1 },
    new { Column1 = "Github", Column2 = 2}
});

Datatable:

var path = Path.Combine(Path.GetTempPath(), $"{Guid.NewGuid()}.xlsx");
var table = new DataTable();
{
    table.Columns.Add("Column1", typeof(string));
    table.Columns.Add("Column2", typeof(decimal));
    table.Rows.Add("MiniExcel", 1);
    table.Rows.Add("Github", 2);
}

MiniExcel.SaveAs(path, table);

Dapper:

using (var connection = GetConnection(connectionString))
{
    var rows = connection.Query(@"select 'MiniExcel' as Column1,1 as Column2 union all select 'Github',2");
    MiniExcel.SaveAs(path, rows);
}

IEnumerable<IDictionary<string, object>>

var values = new List<Dictionary<string, object>>()
{
    new Dictionary<string,object>{{ "Column1", "MiniExcel" }, { "Column2", 1 } },
    new Dictionary<string,object>{{ "Column1", "Github" }, { "Column2", 2 } }
};
MiniExcel.SaveAs(path, values);

output :

Column1	Column2
MiniExcel	1
Github	2

SaveAs 支援 Stream [Try it]

using (var stream = File.Create(path))
{
    stream.SaveAs(values);
}

Excel Column Name/Index/Ignore Attribute

e.g

input excel :

public class ExcelAttributeDemo
{
    [ExcelColumnName("Column1")]
    public string Test1 { get; set; }
    [ExcelColumnName("Column2")]
    public string Test2 { get; set; }
    [ExcelIgnore]
    public string Test3 { get; set; }
    [ExcelColumnIndex("I")] // system will convert "I" to 8 index
    public string Test4 { get; set; } 
    public string Test5 { get; } //wihout set will ignore
    public string Test6 { get; private set; } //un-public set will ignore
    [ExcelColumnIndex(3)] // start with 0
    public string Test7 { get; set; }
}

var rows = MiniExcel.Query<ExcelAttributeDemo>(path).ToList();
Assert.Equal("Column1", rows[0].Test1);
Assert.Equal("Column2", rows[0].Test2);
Assert.Null(rows[0].Test3);
Assert.Equal("Test7", rows[0].Test4);
Assert.Null(rows[0].Test5);
Assert.Null(rows[0].Test6);
Assert.Equal("Test4", rows[0].Test7);

查詢指定 Sheet 名稱

MiniExcel.Query(path, sheetName: "SheetName");
//or
stream.Query(sheetName: "SheetName");

查詢所有 Sheet 名稱跟資料

var sheetNames = MiniExcel.GetSheetNames(path).ToList();
foreach (var sheetName in sheetNames)
{
    var rows = MiniExcel.Query(path, sheetName: sheetName);
}

例子 : SQLite & Dapper 讀取大數據新增到資料庫

note : 請不要呼叫 call ToList/ToArray 等方法，這會將所有資料讀到記憶體內

using (var connection = new SQLiteConnection(connectionString))
{
    connection.Open();
    using (var transaction = connection.BeginTransaction())
    using (var stream = File.OpenRead(path))
    {
	   var rows = stream.Query();
	   foreach (var row in rows)
			 connection.Execute("insert into T (A,B) values (@A,@B)", new { row.A, row.B }, transaction: transaction);
	   transaction.Commit();
    }
}

效能:

例子 : ASP.NET Core 3.1 or MVC 5 下載 Excel Xlsx API Demo

public class ExcelController : Controller
{
    public IActionResult Download()
    {
        var values = new[] {
            new { Column1 = "MiniExcel", Column2 = 1 },
            new { Column1 = "Github", Column2 = 2}
        };
        var stream = new MemoryStream();
        stream.SaveAs(values);
        return File(stream,
            "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
            "demo.xlsx");
    }
}

Excel 類別自動判斷

MiniExcel 預設會根據擴展名或是 Stream 類別判斷是 xlsx 還是 csv，但會有失準時候，請自行指定。

stream.SaveAs(excelType:ExcelType.CSV);
//or
stream.SaveAs(excelType:ExcelType.XLSX);
//or
stream.Query(excelType:ExcelType.CSV);
//or
stream.Query(excelType:ExcelType.XLSX);

Dynamic Query 轉成 IDictionary<string,object> 資料

foreach(IDictionary<string,object> row in MiniExcel.Query(path))
{
    //..
}

侷限與警告

• 目前不支援 xls (97-2003) 或是加密檔案。
• 不支援樣式、字體、寬度等修改，因為 MiniExcel 概念是只專注於值資料，藉此降低記憶體消耗跟提升效率。

參考

• 讀取邏輯 : ExcelDataReader
• API 設計方式 :　StackExchange/Dapper

Contributors :