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It is recommended you find/use an alternate solution. There are newer more capable projects that exist today.

Linq to Excel is a .Net library that allows you to query Excel spreadsheets using the LINQ syntax.

Checkout the introduction video.

You can use NuGet to quickly add LinqToExcel to your project. Just search for linqtoexcel and install the package.

In order to use LinqToExcel, you need to install the Microsoft Microsoft Access Database Engine 2010 Redistributable. If it's not installed, you'll get the following exception:

The 'Microsoft.ACE.OLEDB.12.0' provider is not registered on the local machine.'

Both a 32-bit and 64-bit version are available, select the one that matches your project settings. You can only have one of them installed at a time.

The default query expects the first row to be the header row containing column names that match the property names on the generic class being used. It also expects the data to be in the worksheet named "Sheet1".

var excel = new ExcelQueryFactory("excelFileName");
var indianaCompanies = from c in excel.Worksheet<Company>()
                       where c.State == "IN"
                       select c;

Data from the worksheet named "Sheet1" is queried by default. To query a worksheet with a different name, pass the worksheet name in as an argument.

var excel = new ExcelQueryFactory("excelFileName");
var oldCompanies = from c in excel.Worksheet<Company>("US Companies") //worksheet name = 'US Companies'
                   where c.LaunchDate < new DateTime(1900, 1, 1)
                   select c;

Column names from the worksheet can be mapped to specific property names on the class by using the AddMapping() method. The property name can be passed in as a string or a compile time safe expression.

var excel = new ExcelQueryFactory("excelFileName");
excel.AddMapping<Company>(x => x.State, "Providence"); //maps the "State" property to the "Providence" column
excel.AddMapping("Employees", "Employee Count");       //maps the "Employees" property to the "Employee Count" column

var indianaCompanies = from c in excel.Worksheet<Company>()
	               where c.State == "IN" && c.Employees > 500
	               select c;

Column names can alternately be mapped using the ExcelColumn attribute on properties of the class.

public class Company
{
	[ExcelColumn("Company Title")] //maps the "Name" property to the "Company Title" column
	public string Name { get; set; }

	[ExcelColumn("Providence")] //maps the "State" property to the "Providence" column
	public string State { get; set; }

	[ExcelColumn("Employee Count")] //maps the "Employees" property to the "Employee Count" column
	public string Employees { get; set; }
}

Query results can be returned as LinqToExcel.Row objects which allows you to access a cell's value by using the column name in the string index. Just use the Worksheet() method without a generic argument.

var excel = new ExcelQueryFactory("excelFileName");
var indianaCompanies = from c in excel.Worksheet()
                       where c["State"] == "IN" || c["Zip"] == "46550"
                       select c;

The LinqToExcel.Row class allows you to easily cast a cell's value by using its Cast<>() method

var excel = new ExcelQueryFactory("excelFileName");
var largeCompanies = from c in excel.Worksheet()
                     where c["EmployeeCount"].Cast<int>() > 500
                     select c;

Worksheets that do not contain a header row can also be queried by using the WorksheetNoHeader() method. The cell values are referenced by index.

var excel = new ExcelQueryFactory("excelFileName");
var indianaCompanies = from c in excel.WorksheetNoHeader()
                       where c[2] == "IN" //value in 3rd column
                       select c;

A query can be scoped to only include data from within a named range.

var excel = new ExcelQueryFactory("excelFileName");
var indianaCompanies = from c in excel.NamedRange<Company>("NamedRange") //Selects data within the range named 'NamedRange'
                       where c.State == "IN"
                       select c;

Data from only a specific range of cells within a worksheet can be queried as well. (This is not the same as a named range, which is noted above)

If the first row of the range contains a header row, then use the WorksheetRange() method

var excel = new ExcelQueryFactory("excelFileName");
var indianaCompanies = from c in excel.WorksheetRange<Company>("B3", "G10") //Selects data within the B3 to G10 cell range
                       where c.State == "IN"
                       select c;

If the first row of the range is not a header row, then use the WorksheetRangeNoHeader() method

var excel = new ExcelQueryFactory("excelFileName");
var indianaCompanies = from c in excel.WorksheetRangeNoHeader("B3", "G10") //Selects data within the B3 to G10 cell range
                       where c[2] == "IN" //value in 3rd column (D column in this case)
                       select c;

A specific worksheet can be queried by its index in relation to the other worksheets in the spreadsheet.

The worsheets index order is based on their names alphabetically; not the order they appear in Excel. For example, if a spreadsheet contains 2 worksheets: "ten" and "eleven". Although "eleven" is the second worksheet in Excel, it is actually the first index.

var excel = new ExcelQueryFactory("excelFileName");
var oldCompanies = from c in excel.Worksheet<Company>(1) //Queries the second worksheet in alphabetical order
                   where c.LaunchDate < new DateTime(1900, 1, 1)
                   select c;

Transformations can be applied to cell values before they are set on the class properties. The example below transforms "Y" values in the "IsBankrupt" column to a boolean value of true.

var excel = new ExcelQueryFactory("excelFileName");
excel.AddTransformation<Company>(x => x.IsBankrupt, cellValue => cellValue == "Y");

var bankruptCompanies = from c in excel.Worksheet<Company>()
                        where c.IsBankrupt == true
                        select c;

Data from CSV files can be queried the same way spreadsheets are queried.

var csv = new ExcelQueryFactory("csvFileName");
var indianaCompanies = from c in csv.Worksheet<Company>()
                       where c.State == "IN"
                       select c;

The GetWorksheetNames() method can be used to retrieve the list of worksheet names in a spreadsheet.

var excel = new ExcelQueryFactory("excelFileName");
var worksheetNames = excel.GetWorksheetNames();

The GetColumnNames() method can be used to retrieve the list of column names in a worksheet.

var excel = new ExcelQueryFactory("excelFileName");
var columnNames = excel.GetColumnNames("worksheetName");

The StrictMapping property can be set to:

• 'WorksheetStrict' in order to enforce all worksheet columns are mapped to a class property.
• 'ClassStrict' to enforce all class properties are mapped to a worksheet column.
• 'Both' to enforce all worksheet columns map to a class property and vice versa.

The implied default StrictMapping value is 'None'. A StrictMappingException is thrown when the specified mapping condition isn't satisified.

var excel = new ExcelQueryFactory("excelFileName");
excel.StrictMapping = StrictMappingType.Both;

If you are using None or ClassStrict mapping, you can retain unmapped columns by implementing the IContainsUnmappedCells interface. This will put all values from the unmapped columns into a dictionary on your class named UnmappedCells.

Let's say the only field you're guaranteed to have is a Name column, and the rest of the columns can be different per spreadsheet. You could write your Company class like this, implementing IContainsUnmappedCells:

public class Company : IContainsUnmappedCells
{
    public string Name { get; set; }
    public IDictionary<string, Cell> UnmappedCells { get; } = new Dictionary<string, Cell>();
}

Given the following data set:

You can query normally and all other fields will be available in the UnmappedCells dictionary:

var company = from c in excel.Worksheet<Company>()
              where c.Name == "ACME"
              select c;

// company.UnmappedCells["CEO"] == "Bugs Bunny"
// company.UnmappedCells["EmployeeCount"].Cast<int>() == 25
// company.UnmappedCells["StartDate"].Cast<DateTime>() == new DateTime(1918, 11, 11)

LinqToExcel can use the Jet or Ace database engine, and it automatically determines the database engine to use by the file extension. You can manually set the database engine with the DatabaseEngine property

var excel = new ExcelQueryFactory("excelFileName");
excel.DatabaseEngine == DatabaseEngine.Ace;

The TrimSpaces property can be used to automatically trim leading and trailing white spaces.

var excel = new ExcelQueryFactory("excelFileName");
excel.TrimSpaces = TrimSpacesType.Both;

There are 4 options for TrimSpaces:

• None - does not trim any white space. This is the default
• Both - trims white space from the beginning and end
• Start - trims white space from only the beginning
• End - trims white space from only the end

By default a new connection is created and disposed of for each query ran. If you want to use the same connection on all queries performed by the IExcelQueryFactory then set the UsePersistentConnection property to true.

Make sure you properly dispose the ExcelQueryFactory if you use a persistent connection.

var excel = new ExcelQueryFactory("excelFileName");
excel.UsePersistentConnection = true;
    
try
{
	var allCompanies = from c in excel.Worksheet<Company>()
        		   select c;
}
finally
{
	excel.Dispose();
}

Set the ReadOnly property to true to open the file in readonly mode. The default value is false.

var excel = new ExcelQueryFactory("excelFileName");
excel.ReadOnly = true;

Set the Lazy property to true to read rows one at a time instead of pulling everything into memory at once. Under the hood, this is accomplished using C# yield statements.

If you read lazily, you will want to make sure you dispose of the IEnumerator<T> when finished. C# will do this automatically for you in foreach statements and most, if not all, LINQ statements (e.g. FirstOrDefault() reads the first row and disposes automatically).

var excel = new ExcelQueryFactory("excelFileName");
excel.Lazy = true;

When mapping a field to a type, if there is a type conversion error, an exception is thrown. You can overcome the default exception throwing behavior by implementing the IAllowFieldTypeConversionExceptions interface on your class. Any class that implements this interface must carry a non-null list of ExcelException in FieldTypeConversionExceptions. If any exceptions occur during the field type conversion, it will be added to this list rather than thrown.

Note that you should check the exceptions list before accessing any values on your strongly typed row, since any fields listed in the exception list will be in an indeterminate state.

By default, the OLE DB Provider will try to enlist in an open TransactionScope and will fail because Excel does not allow for transactions. To avoid this behavior and opt out of TransactionScope for the connection, set OleDbServices to AllServicesExceptPoolingAndAutoEnlistment.

See Pooling in the Microsoft Data Access Components for more information.

var excel = new ExcelQueryFactory("excelFileName");
excel.OleDbServices = Query.OleDbServices.AllServicesExceptPoolingAndAutoEnlistment;

If the file is in a different encoding use the CodePageIdentifer so the setting is passed to the engine.

See Code Page Identifiers for a complete listing of Code Page Identifiers and their corresponding encoding.

var excel = new ExcelQueryFactory("excelFileName");
//Set the encoding to UTF-8
excel.CodePageIdentifier = 65001;

The SkipEmptyRows property can be used to skip all rows that do not have any values.

var excel = new ExcelQueryFactory("excelFileName");
excel.SkipEmptyRows = true;