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Your Star and Donate can make MiniExcel better

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Youtube Tutorial Video : MiniExcel

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Introduction

MiniExcel is simple and efficient to avoid OOM's .NET processing Excel tool.

At present, most popular frameworks need to load all the data into the memory to facilitate operation, but it will cause memory consumption problems. MiniExcel tries to use algorithm from a stream to reduce the original 1000 MB occupation to a few MB to avoid OOM(out of memory).

Features

• Low memory consumption, avoid OOM (out of memory) and full GC
• Support real-time operation of each row of data
• Support LINQ deferred execution, it can do low-consumption, fast paging and other complex queries
• Lightweight, without Microsoft Office installed, no COM+, DLL size is less than 150KB
• Easy API style to read/write/fill excel

Get Started

• Import/Query Excel

• Export/Create Excel

• Excel Template

• Excel Column Name/Index/Ignore Attribute

• Examples

Installation

You can install the package from NuGet

Release Notes

Please Check Release Notes

TODO

Please Check TODO

Performance

Benchmarks logic can be found in MiniExcel.Benchmarks , and test cli

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

Output from the latest run is :

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  

Benchmark History : Link

Import/Query Excel

Logic : Test1,000,000x10.xlsx as performance test basic file, 1,000,000 rows * 10 columns "HelloWorld" cells, 23 MB file size

Library	Method	Max Memory Usage	Mean
MiniExcel	'MiniExcel QueryFirst'	0.109 MB	0.0007264 sec
ExcelDataReader	'ExcelDataReader QueryFirst'	15.24 MB	10.66421 sec
MiniExcel	'MiniExcel Query'	17.3 MB	14.17933 sec
ExcelDataReader	'ExcelDataReader Query'	17.3 MB	22.56508 sec
Epplus	'Epplus QueryFirst'	1,452 MB	18.19801 sec
Epplus	'Epplus Query'	1,451 MB	23.64747 sec
OpenXmlSDK	'OpenXmlSDK Query'	1,412 MB	52.00327 sec
OpenXmlSDK	'OpenXmlSDK QueryFirst'	1,413 MB	52.34865 sec
ClosedXml	'ClosedXml QueryFirst'	2,158 MB	66.18897 sec
ClosedXml	'ClosedXml Query'	2,184 MB	191.43412 sec

Export/Create Excel

Logic : create a total of 10,000,000 "HelloWorld" excel

Library	Method	Max Memory Usage	Mean
MiniExcel	'MiniExcel Create Xlsx'	15 MB	11.53181 sec
Epplus	'Epplus Create Xlsx'	1,204 MB	22.50971 sec
OpenXmlSdk	'OpenXmlSdk Create Xlsx'	2,621 MB	42.47399 sec
ClosedXml	'ClosedXml Create Xlsx'	7,141 MB	140.93992 sec

Excel Query/Import

1. Execute a query and map the results to a strongly typed IEnumerable [Try it]

Recommand to use Stream.Query because of better efficiency.

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>();

2. Execute a query and map it to a list of dynamic objects without using head [Try it]

• dynamic key is A.B.C.D..

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);
}

3. Execute a query with first header row [Try it]

note : same column name use last right one

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);
}

4. Query Support LINQ Extension First/Take/Skip ...etc

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);
}

Performance between MiniExcel/ExcelDataReader/ClosedXML/EPPlus

5. Query by sheet name

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

6. Query all sheet name and rows

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

7. Get Columns

var columns = MiniExcel.GetColumns(path); // e.g result : ["A","B"...]

var cnt = columns.Count;  // get column count

8. Dynamic Query cast row to IDictionary<string,object>

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

// or 
var rows = MiniExcel.Query(path).Cast<IDictionary<string,object>>(); 

9. Query Excel return DataTable

Not recommended, because DataTable will load all data into memory and lose MiniExcel's low memory consumption feature.

var table = MiniExcel.QueryAsDataTable(path, useHeaderRow: true);

10. Specify the cell to start reading data

MiniExcel.Query(path,useHeaderRow:true,startCell:"B3")

11. Fill Merged Cells

Note: The efficiency is slower compared to not using merge fill

Reason: The OpenXml standard puts mergeCells at the bottom of the file, which leads to the need to foreach the sheetxml twice

	var config = new OpenXmlConfiguration()
	{
		FillMergedCells = true
	};
	var rows = MiniExcel.Query(path, configuration: config);

support variable length and width multi-row and column filling

12. Reading big file by disk-base cache (Disk-Base Cache - SharedString)

If the SharedStrings size exceeds 5 MB, MiniExcel default will use local disk cache, e.g, 10x100000.xlsx(one million rows data), when disable disk cache the maximum memory usage is 195MB, but able disk cache only needs 65MB. Note, this optimization needs some efficiency cost, so this case will increase reading time from 7.4 seconds to 27.2 seconds, If you don't need it that you can disable disk cache with the following code:

var config = new OpenXmlConfiguration { EnableSharedStringCache = false };
MiniExcel.Query(path,configuration: config)

You can use SharedStringCacheSize to change the sharedString file size beyond the specified size for disk caching

var config = new OpenXmlConfiguration { SharedStringCacheSize=500*1024*1024 };
MiniExcel.Query(path, configuration: config);

Create/Export Excel

1. Must be a non-abstract type with a public parameterless constructor .

2. MiniExcel support parameter IEnumerable Deferred Execution, If you want to use least memory, please do not call methods such as ToList

e.g : ToList or not memory usage

1. Anonymous or strongly type [Try it]

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

2. 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);

Create File Result :

Column1	Column2
MiniExcel	1
Github	2

3. IDataReader

• Recommended, it can avoid to load all data into memory

MiniExcel.SaveAs(path, reader);

DataReader export multiple sheets (recommand by Dapper ExecuteReader)

using (var cnn = Connection)
{
    cnn.Open();
    var sheets = new Dictionary<string,object>();
    sheets.Add("sheet1", cnn.ExecuteReader("select 1 id"));
    sheets.Add("sheet2", cnn.ExecuteReader("select 2 id"));
    MiniExcel.SaveAs("Demo.xlsx", sheets);
}

4. Datatable

• Not recommended, it will load all data into memory

• DataTable use Caption for column name first, then use columname

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);

5. Dapper Query

• Not recommended, it will load all data into memory, please use ExecuteReader

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);
}

6. SaveAs to MemoryStream [Try it]

using (var stream = new MemoryStream()) //support FileStream,MemoryStream ect.
{
    stream.SaveAs(values);
}

e.g : api of export excel

public IActionResult DownloadExcel()
{
    var values = new[] {
        new { Column1 = "MiniExcel", Column2 = 1 },
        new { Column1 = "Github", Column2 = 2}
    };

    var memoryStream = new MemoryStream();
    memoryStream.SaveAs(values);
    memoryStream.Seek(0, SeekOrigin.Begin);
    return new FileStreamResult(memoryStream, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet")
    {
        FileDownloadName = "demo.xlsx"
    };
}

7. Create Multiple Sheets

// 1. Dictionary<string,object>
var users = new[] { new { Name = "Jack", Age = 25 }, new { Name = "Mike", Age = 44 } };
var department = new[] { new { ID = "01", Name = "HR" }, new { ID = "02", Name = "IT" } };
var sheets = new Dictionary<string, object>
{
    ["users"] = users,
    ["department"] = department
};
MiniExcel.SaveAs(path, sheets);

// 2. DataSet
var sheets = new DataSet();
sheets.Add(UsersDataTable);
sheets.Add(DepartmentDataTable);
//..
MiniExcel.SaveAs(path, sheets);

8. TableStyles Options

Default style

Without style configuration

var config = new OpenXmlConfiguration()
{
     TableStyles = TableStyles.None
};
MiniExcel.SaveAs(path, value,configuration:config);

9. AutoFilter

Since v0.19.0 OpenXmlConfiguration.AutoFilter can en/unable AutoFilter , default value is true, and setting AutoFilter way:

MiniExcel.SaveAs(path, value, configuration: new OpenXmlConfiguration() { AutoFilter = false });

10. Create Image

var value = new[] {
    new { Name="github",Image=File.ReadAllBytes(PathHelper.GetFile("images/github_logo.png"))},
    new { Name="google",Image=File.ReadAllBytes(PathHelper.GetFile("images/google_logo.png"))},
    new { Name="microsoft",Image=File.ReadAllBytes(PathHelper.GetFile("images/microsoft_logo.png"))},
    new { Name="reddit",Image=File.ReadAllBytes(PathHelper.GetFile("images/reddit_logo.png"))},
    new { Name="statck_overflow",Image=File.ReadAllBytes(PathHelper.GetFile("images/statck_overflow_logo.png"))},
};
MiniExcel.SaveAs(path, value);

11. Byte Array File Export

Since 1.22.0, when value type is byte[] then system will save file path at cell by default, and when import system can be converted to byte[]. And if you don't want to use it, you can set OpenXmlConfiguration.EnableConvertByteArray to false, it can improve the system efficiency.

Fill Data To Excel Template

• The declaration is similar to Vue template {{variable name}}, or the collection rendering {{collection name.field name}}
• Collection rendering support IEnumerable/DataTable/DapperRow

1. Basic Fill

Template:

Result:

Code:

// 1. By POCO
var value = new
{
    Name = "Jack",
    CreateDate = new DateTime(2021, 01, 01),
    VIP = true,
    Points = 123
};
MiniExcel.SaveAsByTemplate(path, templatePath, value);


// 2. By Dictionary
var value = new Dictionary<string, object>()
{
    ["Name"] = "Jack",
    ["CreateDate"] = new DateTime(2021, 01, 01),
    ["VIP"] = true,
    ["Points"] = 123
};
MiniExcel.SaveAsByTemplate(path, templatePath, value);

2. IEnumerable Data Fill

Note1: Use the first IEnumerable of the same column as the basis for filling list

Template:

Result:

Code:

//1. By POCO
var value = new
{
    employees = new[] {
        new {name="Jack",department="HR"},
        new {name="Lisa",department="HR"},
        new {name="John",department="HR"},
        new {name="Mike",department="IT"},
        new {name="Neo",department="IT"},
        new {name="Loan",department="IT"}
    }
};
MiniExcel.SaveAsByTemplate(path, templatePath, value);

//2. By Dictionary
var value = new Dictionary<string, object>()
{
    ["employees"] = new[] {
        new {name="Jack",department="HR"},
        new {name="Lisa",department="HR"},
        new {name="John",department="HR"},
        new {name="Mike",department="IT"},
        new {name="Neo",department="IT"},
        new {name="Loan",department="IT"}
    }
};
MiniExcel.SaveAsByTemplate(path, templatePath, value);

3. Complex Data Fill

Note: Support multi-sheets and using same varible

Template:

Result:

// 1. By POCO
var value = new
{
    title = "FooCompany",
    managers = new[] {
        new {name="Jack",department="HR"},
        new {name="Loan",department="IT"}
    },
    employees = new[] {
        new {name="Wade",department="HR"},
        new {name="Felix",department="HR"},
        new {name="Eric",department="IT"},
        new {name="Keaton",department="IT"}
    }
};
MiniExcel.SaveAsByTemplate(path, templatePath, value);

// 2. By Dictionary
var value = new Dictionary<string, object>()
{
    ["title"] = "FooCompany",
    ["managers"] = new[] {
        new {name="Jack",department="HR"},
        new {name="Loan",department="IT"}
    },
    ["employees"] = new[] {
        new {name="Wade",department="HR"},
        new {name="Felix",department="HR"},
        new {name="Eric",department="IT"},
        new {name="Keaton",department="IT"}
    }
};
MiniExcel.SaveAsByTemplate(path, templatePath, value);

4. Fill Big Data Performance

NOTE: Using IEnumerable deferred execution not ToList can save max memory usage in MiniExcel

5. Cell value auto mapping type

Template

Result

Class

public class Poco
{
    public string @string { get; set; }
    public int? @int { get; set; }
    public decimal? @decimal { get; set; }
    public double? @double { get; set; }
    public DateTime? datetime { get; set; }
    public bool? @bool { get; set; }
    public Guid? Guid { get; set; }
}

Code

var poco = new TestIEnumerableTypePoco { @string = "string", @int = 123, @decimal = decimal.Parse("123.45"), @double = (double)123.33, @datetime = new DateTime(2021, 4, 1), @bool = true, @Guid = Guid.NewGuid() };
var value = new
{
    Ts = new[] {
        poco,
        new TestIEnumerableTypePoco{},
        null,
        poco
    }
};
MiniExcel.SaveAsByTemplate(path, templatePath, value);

6. Example : List Github Projects

Template

Result

Code

var projects = new[]
{
    new {Name = "MiniExcel",Link="https://github.com/shps951023/MiniExcel",Star=146, CreateTime=new DateTime(2021,03,01)},
    new {Name = "HtmlTableHelper",Link="https://github.com/shps951023/HtmlTableHelper",Star=16, CreateTime=new DateTime(2020,02,01)},
    new {Name = "PocoClassGenerator",Link="https://github.com/shps951023/PocoClassGenerator",Star=16, CreateTime=new DateTime(2019,03,17)}
};
var value = new
{
    User = "ITWeiHan",
    Projects = projects,
    TotalStar = projects.Sum(s => s.Star)
};
MiniExcel.SaveAsByTemplate(path, templatePath, value);

7. DataTable as parameter

var managers = new DataTable();
{
    managers.Columns.Add("name");
    managers.Columns.Add("department");
    managers.Rows.Add("Jack", "HR");
    managers.Rows.Add("Loan", "IT");
}
var value = new Dictionary<string, object>()
{
    ["title"] = "FooCompany",
    ["managers"] = managers,
};
MiniExcel.SaveAsByTemplate(path, templatePath, value);

8. Other

1. Checking template parameter key

Since V1.24.0 , default ignore template missing parameter key and replace it with empty string, IgnoreTemplateParameterMissing can control throwing exception or not.

var config = new OpenXmlConfiguration()
{
    IgnoreTemplateParameterMissing = false,
};
MiniExcel.SaveAsByTemplate(path, templatePath, value, config)

Excel Column Name/Index/Ignore Attribute

1. Specify the column name, column index, column ignore

Excel Example

Code

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);

2. Custom Format (ExcelFormatAttribute)

Since V0.21.0 support class which contains ToString(string content) method format

Class

public class Dto
{
    public string Name { get; set; }

    [ExcelFormat("MMMM dd, yyyy")]
    public DateTime InDate { get; set; }
}

Code

var value = new Dto[] {
    new Issue241Dto{ Name="Jack",InDate=new DateTime(2021,01,04)},
    new Issue241Dto{ Name="Henry",InDate=new DateTime(2020,04,05)},
};
MiniExcel.SaveAs(path, value);

Result

Query supports custom format conversion

3. Set Column Width(ExcelColumnWidthAttribute)

public class Dto
{
    [ExcelColumnWidth(20)]
    public int ID { get; set; }
    [ExcelColumnWidth(15.50)]
    public string Name { get; set; }
}

4. Multiple column names mapping to the same property.

public class Dto
{
    [ExcelColumnName(excelColumnName:"EmployeeNo",aliases:new[] { "EmpNo","No" })]
    public string Empno { get; set; }
    public string Name { get; set; }
}

5. System.ComponentModel.DisplayNameAttribute = ExcelColumnName.excelColumnNameAttribute

Since 1.24.0, system supports System.ComponentModel.DisplayNameAttribute = ExcelColumnName.excelColumnNameAttribute

public class TestIssueI4TXGTDto
{
    public int ID { get; set; }
    public string Name { get; set; }
    [DisplayName("Specification")]
    public string Spc { get; set; }
    [DisplayName("Unit Price")]
    public decimal Up { get; set; }
}

6. ExcelColumnAttribute

Since V1.26.0, multiple attributes can be simplified like :

        public class TestIssueI4ZYUUDto
        {
            [ExcelColumn(Name = "ID",Index =0)]
            public string MyProperty { get; set; }
            [ExcelColumn(Name = "CreateDate", Index = 1,Format ="yyyy-MM",Width =100)]
            public DateTime MyProperty2 { get; set; }
        }

7. DynamicColumnAttribute

Since V1.26.0, we can set the attributes of Column dynamically

            var config = new OpenXmlConfiguration
            {
                DynamicColumns = new DynamicExcelColumn[] { 
                    new DynamicExcelColumn("id"){Ignore=true},
                    new DynamicExcelColumn("name"){Index=1,Width=10},
                    new DynamicExcelColumn("createdate"){Index=0,Format="yyyy-MM-dd",Width=15},
                    new DynamicExcelColumn("point"){Index=2,Name="Account Point"},
                }
            };
            var path = PathHelper.GetTempPath();
            var value = new[] { new { id = 1, name = "Jack", createdate = new DateTime(2022, 04, 12) ,point = 123.456} };
            MiniExcel.SaveAs(path, value, configuration: config);

Excel Type Auto Check

• MiniExcel will check whether it is xlsx or csv based on the file extension by default, but there may be inaccuracy, please specify it manually.
• Stream cannot be know from which excel, please specify it manually.

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

CSV

Note

• Default return string type, and value will not be converted to numbers or datetime, unless the type is defined by strong typing generic.

Custom separator

The default is , as the separator, you can modify the Seperator property for customization

var config = new MiniExcelLibs.Csv.CsvConfiguration() 
{
    Seperator=';'
};
MiniExcel.SaveAs(path, values,configuration: config);

Custom line break

The default is \r\n as the newline character, you can modify the NewLine property for customization

var config = new MiniExcelLibs.Csv.CsvConfiguration() 
{
    NewLine='\n'
};
MiniExcel.SaveAs(path, values,configuration: config);

Custom coding

• The default encoding is "Detect Encoding From Byte Order Marks" (detectEncodingFromByteOrderMarks: true)
• f you have custom encoding requirements, please modify the StreamReaderFunc / StreamWriterFunc property

// Read
var config = new MiniExcelLibs.Csv.CsvConfiguration()
{
    StreamReaderFunc = (stream) => new StreamReader(stream,Encoding.GetEncoding("gb2312"))
};
var rows = MiniExcel.Query(path, true,excelType:ExcelType.CSV,configuration: config);

// Write
var config = new MiniExcelLibs.Csv.CsvConfiguration()
{
    StreamWriterFunc = (stream) => new StreamWriter(stream, Encoding.GetEncoding("gb2312"))
};
MiniExcel.SaveAs(path, value,excelType:ExcelType.CSV, configuration: config);

DataReader

1. GetReader

Since 1.23.0, you can GetDataReader

    using (var reader = MiniExcel.GetReader(path,true))
    {
        while (reader.Read())
        {
            for (int i = 0; i < reader.FieldCount; i++)
            {
                var value = reader.GetValue(i);
            }
        }
    }

Async

• v0.17.0 support Async (thanks isdaniel ( SHIH,BING-SIOU)](https://github.com/isdaniel))

public static Task SaveAsAsync(string path, object value, bool printHeader = true, string sheetName = "Sheet1", ExcelType excelType = ExcelType.UNKNOWN, IConfiguration configuration = null)
public static Task SaveAsAsync(this Stream stream, object value, bool printHeader = true, string sheetName = "Sheet1", ExcelType excelType = ExcelType.XLSX, IConfiguration configuration = null)
public static Task<IEnumerable<dynamic>> QueryAsync(string path, bool useHeaderRow = false, string sheetName = null, ExcelType excelType = ExcelType.UNKNOWN, string startCell = "A1", IConfiguration configuration = null)
public static Task<IEnumerable<T>> QueryAsync<T>(this Stream stream, string sheetName = null, ExcelType excelType = ExcelType.UNKNOWN, string startCell = "A1", IConfiguration configuration = null) where T : class, new()    
public static Task<IEnumerable<T>> QueryAsync<T>(string path, string sheetName = null, ExcelType excelType = ExcelType.UNKNOWN, string startCell = "A1", IConfiguration configuration = null) where T : class, new() 
public static Task<IEnumerable<IDictionary<string, object>>> QueryAsync(this Stream stream, bool useHeaderRow = false, string sheetName = null, ExcelType excelType = ExcelType.UNKNOWN, string startCell = "A1", IConfiguration configuration = null)
public static Task SaveAsByTemplateAsync(this Stream stream, string templatePath, object value)
public static Task SaveAsByTemplateAsync(this Stream stream, byte[] templateBytes, object value)    
public static Task SaveAsByTemplateAsync(string path, string templatePath, object value)
public static Task SaveAsByTemplateAsync(string path, byte[] templateBytes, object value) 
public static Task<DataTable> QueryAsDataTableAsync(string path, bool useHeaderRow = true, string sheetName = null, ExcelType excelType = ExcelType.UNKNOWN, string startCell = "A1", IConfiguration configuration = null)

• v1.25.0 support cancellationToken。

Others

1. Enum

Be sure excel & property name same, system will auto mapping (case insensitive)

Since V0.18.0 support Enum Description

public class Dto
{
    public string Name { get; set; }
    public I49RYZUserType UserType { get; set; }
}      

public enum Type
{
    [Description("General User")]
    V1,
    [Description("General Administrator")]
    V2,
    [Description("Super Administrator")]
    V3
}

2. Convert CSV to XLSX or Convert XLSX to CSV

MiniExcel.ConvertXlsxToCsv(xlsxPath, csvPath);
MiniExcel.ConvertXlsxToCsv(xlsxStream, csvStream);
MiniExcel.ConvertXlsxToCsv(csvPath, xlsxPath);
MiniExcel.ConvertXlsxToCsv(csvStream, xlsxStream);

3. Custom CultureInfo

Since 1.22.0, you can custom CultureInfo like below, system default CultureInfo.InvariantCulture.

var config = new CsvConfiguration()
{
	Culture = new CultureInfo("fr-FR"),
};
MiniExcel.SaveAs(path, value, configuration: config);

// or
MiniExcel.Query(path, configuration: config);

Examples:

1. SQLite & Dapper Large Size File SQL Insert Avoid OOM

note : please don't call ToList/ToArray methods after Query, it'll load all data into memory

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();
    }
}

performance:

2. ASP.NET Core 3.1 or MVC 5 Download/Upload Excel Xlsx API Demo Try it

public class ApiController : Controller
{
    public IActionResult Index()
    {
        return new ContentResult
        {
            ContentType = "text/html",
            StatusCode = (int)HttpStatusCode.OK,
            Content = @"<html><body>
<a href='api/DownloadExcel'>DownloadExcel</a><br>
<a href='api/DownloadExcelFromTemplatePath'>DownloadExcelFromTemplatePath</a><br>
<a href='api/DownloadExcelFromTemplateBytes'>DownloadExcelFromTemplateBytes</a><br>
<p>Upload Excel</p>
<form method='post' enctype='multipart/form-data' action='/api/uploadexcel'>
    <input type='file' name='excel'> <br>
    <input type='submit' >
</form>
</body></html>"
        };
    }

    public IActionResult DownloadExcel()
    {
        var values = new[] {
            new { Column1 = "MiniExcel", Column2 = 1 },
            new { Column1 = "Github", Column2 = 2}
        };
        var memoryStream = new MemoryStream();
        memoryStream.SaveAs(values);
        memoryStream.Seek(0, SeekOrigin.Begin);
        return new FileStreamResult(memoryStream, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet")
        {
            FileDownloadName = "demo.xlsx"
        };
    }

    public IActionResult DownloadExcelFromTemplatePath()
    {
        string templatePath = "TestTemplateComplex.xlsx";

        Dictionary<string, object> value = new Dictionary<string, object>()
        {
            ["title"] = "FooCompany",
            ["managers"] = new[] {
                new {name="Jack",department="HR"},
                new {name="Loan",department="IT"}
            },
            ["employees"] = new[] {
                new {name="Wade",department="HR"},
                new {name="Felix",department="HR"},
                new {name="Eric",department="IT"},
                new {name="Keaton",department="IT"}
            }
        };

        MemoryStream memoryStream = new MemoryStream();
        memoryStream.SaveAsByTemplate(templatePath, value);
        memoryStream.Seek(0, SeekOrigin.Begin);
        return new FileStreamResult(memoryStream, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet")
        {
            FileDownloadName = "demo.xlsx"
        };
    }

    private static Dictionary<string, Byte[]> TemplateBytesCache = new Dictionary<string, byte[]>();

    static ApiController()
    {
        string templatePath = "TestTemplateComplex.xlsx";
        byte[] bytes = System.IO.File.ReadAllBytes(templatePath);
        TemplateBytesCache.Add(templatePath, bytes);
    }

    public IActionResult DownloadExcelFromTemplateBytes()
    {
        byte[] bytes = TemplateBytesCache["TestTemplateComplex.xlsx"];

        Dictionary<string, object> value = new Dictionary<string, object>()
        {
            ["title"] = "FooCompany",
            ["managers"] = new[] {
                new {name="Jack",department="HR"},
                new {name="Loan",department="IT"}
            },
            ["employees"] = new[] {
                new {name="Wade",department="HR"},
                new {name="Felix",department="HR"},
                new {name="Eric",department="IT"},
                new {name="Keaton",department="IT"}
            }
        };

        MemoryStream memoryStream = new MemoryStream();
        memoryStream.SaveAsByTemplate(bytes, value);
        memoryStream.Seek(0, SeekOrigin.Begin);
        return new FileStreamResult(memoryStream, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet")
        {
            FileDownloadName = "demo.xlsx"
        };
    }

    public IActionResult UploadExcel(IFormFile excel)
    {
        var stream = new MemoryStream();
        excel.CopyTo(stream);

        foreach (var item in stream.Query(true))
        {
            // do your logic etc.
        }

        return Ok("File uploaded successfully");
    }
}

3. Paging Query

void Main()
{
	var rows = MiniExcel.Query(path);
	
	Console.WriteLine("==== No.1 Page ====");
	Console.WriteLine(Page(rows,pageSize:3,page:1));
	Console.WriteLine("==== No.50 Page ====");
	Console.WriteLine(Page(rows,pageSize:3,page:50));
	Console.WriteLine("==== No.5000 Page ====");
	Console.WriteLine(Page(rows,pageSize:3,page:5000));
}

public static IEnumerable<T> Page<T>(IEnumerable<T> en, int pageSize, int page)
{
	return en.Skip(page * pageSize).Take(pageSize);
}

4. WebForm export Excel by memorystream

var fileName = "Demo.xlsx";
var sheetName = "Sheet1";
HttpResponse response = HttpContext.Current.Response;
response.Clear();
response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
response.AddHeader("Content-Disposition", $"attachment;filename=\"{fileName}\"");
var values = new[] {
    new { Column1 = "MiniExcel", Column2 = 1 },
    new { Column1 = "Github", Column2 = 2}
};
var memoryStream = new MemoryStream();
memoryStream.SaveAs(values, sheetName: sheetName);
memoryStream.Seek(0, SeekOrigin.Begin);
memoryStream.CopyTo(Response.OutputStream);
response.End();

5. Dynamic i18n multi-language and role authority management

Like the example, create a method to handle i18n and permission management, and use yield return to return IEnumerable<Dictionary<string, object>> to achieve dynamic and low-memory processing effects

void Main()
{
	var value = new Order[] {
		new Order(){OrderNo = "SO01",CustomerID="C001",ProductID="P001",Qty=100,Amt=500},
		new Order(){OrderNo = "SO02",CustomerID="C002",ProductID="P002",Qty=300,Amt=400},
	};

	Console.WriteLine("en-Us and Sales role");
	{
		var path = Path.GetTempPath() + Guid.NewGuid() + ".xlsx";
		var lang = "en-US";
		var role = "Sales";
		MiniExcel.SaveAs(path, GetOrders(lang, role, value));
		MiniExcel.Query(path, true).Dump();
	}

	Console.WriteLine("zh-CN and PMC role");
	{
		var path = Path.GetTempPath() + Guid.NewGuid() + ".xlsx";
		var lang = "zh-CN";
		var role = "PMC";
		MiniExcel.SaveAs(path, GetOrders(lang, role, value));
		MiniExcel.Query(path, true).Dump();
	}
}

private IEnumerable<Dictionary<string, object>> GetOrders(string lang, string role, Order[] orders)
{
	foreach (var order in orders)
	{
		var newOrder = new Dictionary<string, object>();

		if (lang == "zh-CN")
		{
			newOrder.Add("客户编号", order.CustomerID);
			newOrder.Add("订单编号", order.OrderNo);
			newOrder.Add("产品编号", order.ProductID);
			newOrder.Add("数量", order.Qty);
			if (role == "Sales")
				newOrder.Add("价格", order.Amt);
			yield return newOrder;
		}
		else if (lang == "en-US")
		{
			newOrder.Add("Customer ID", order.CustomerID);
			newOrder.Add("Order No", order.OrderNo);
			newOrder.Add("Product ID", order.ProductID);
			newOrder.Add("Quantity", order.Qty);
			if (role == "Sales")
				newOrder.Add("Amount", order.Amt);
			yield return newOrder;
		}
		else
		{
			throw new InvalidDataException($"lang {lang} wrong");
		}
	}
}

public class Order
{
	public string OrderNo { get; set; }
	public string CustomerID { get; set; }
	public decimal Qty { get; set; }
	public string ProductID { get; set; }
	public decimal Amt { get; set; }
}

FAQ

Q: Excel header title not equal class property name, how to mapping?

A. Please use ExcelColumnName attribute

Q. How to query or export multiple-sheets?

A. GetSheetNames method with Query sheetName parameter.

var sheets = MiniExcel.GetSheetNames(path);
foreach (var sheet in sheets)
{
    Console.WriteLine($"sheet name : {sheet} ");
    var rows = MiniExcel.Query(path,useHeaderRow:true,sheetName:sheet);
    Console.WriteLine(rows);
}

Q. Whether to use Count will load all data into the memory?

No, the image test has 1 million rows*10 columns of data, the maximum memory usage is <60MB, and it takes 13.65 seconds

Q. How does Query use integer indexs?

The default index of Query is the string Key: A,B,C.... If you want to change to numeric index, please create the following method to convert

void Main()
{
	var path = @"D:\git\MiniExcel\samples\xlsx\TestTypeMapping.xlsx";
	var rows = MiniExcel.Query(path,true);
	foreach (var r in ConvertToIntIndexRows(rows))
	{
		Console.Write($"column 0 : {r[0]} ,column 1 : {r[1]}");
		Console.WriteLine();
	}
}

private IEnumerable<Dictionary<int, object>> ConvertToIntIndexRows(IEnumerable<object> rows)
{
	ICollection<string> keys = null;
	var isFirst = true;
	foreach (IDictionary<string,object> r in rows)
	{
		if(isFirst)
		{
			keys = r.Keys;
			isFirst = false;
		}
		
		var dic = new Dictionary<int, object>();
		var index = 0;
		foreach (var key in keys)
			dic[index++] = r[key];
		yield return dic;
	}
}

Q. No title empty excel is generated when the value is empty when exporting Excel

Because MiniExcel uses a logic similar to JSON.NET to dynamically get type from values to simplify API operations, type cannot be knew without data. You can check issue #133 for understanding.

Strong type & DataTable will generate headers, but Dictionary are still empty Excel

Q. How to stop the foreach when blank row?

MiniExcel can be used with LINQ TakeWhile to stop foreach iterator.

Q. How to remove empty rows?

IEnumerable :

public static IEnumerable<dynamic> QueryWithoutEmptyRow(Stream stream, bool useHeaderRow, string sheetName, ExcelType excelType, string startCell, IConfiguration configuration)
{
	var rows = stream.Query(useHeaderRow,sheetName,excelType,startCell,configuration);
	foreach (IDictionary<string,object> row in rows)
	{
		if(row.Keys.Any(key=>row[key]!=null))
			yield return row;
	}
}

DataTable :

public static DataTable QueryAsDataTableWithoutEmptyRow(Stream stream, bool useHeaderRow, string sheetName, ExcelType excelType, string startCell, IConfiguration configuration)
{
	if (sheetName == null && excelType != ExcelType.CSV) /*Issue #279*/
		sheetName = stream.GetSheetNames().First();

	var dt = new DataTable(sheetName);
	var first = true;
	var rows = stream.Query(useHeaderRow,sheetName,excelType,startCell,configuration);
	foreach (IDictionary<string, object> row in rows)
	{
		if (first)
		{

			foreach (var key in row.Keys)
			{
				var column = new DataColumn(key, typeof(object)) { Caption = key };
				dt.Columns.Add(column);
			}

			dt.BeginLoadData();
			first = false;
		}

		var newRow = dt.NewRow();
		var isNull=true;
		foreach (var key in row.Keys)
		{
			var _v = row[key];
			if(_v!=null)
				isNull = false;
			newRow[key] = _v; 
		}
		
		if(!isNull)
			dt.Rows.Add(newRow);
	}

	dt.EndLoadData();
	return dt;
}

Q. How SaveAs(path,value) to replace exists file and without throwing "The file ...xlsx already exists error"

Please use Stream class to custom file creating logic, e.g:

	using (var stream = File.Create("Demo.xlsx"))
		MiniExcel.SaveAs(stream,value);

or, since V1.25.0, SaveAs support overwriteFile parameter for enable/unable overwriting exist file

	MiniExcel.SaveAs(path, value, overwriteFile: true);

Limitations and caveats

• Not support xls and encrypted file now
• xlsm only support Query

Reference

ExcelDataReader / ClosedXML / Dapper / ExcelNumberFormat

Thanks

Jetbrains

Thanks for providing a free All product IDE for this project (License)

Contributors