DataRowExtensions.Field<T> Method (DataRow, String)
Provides strongly-typed access to each of the column values in the specified row. The Field method also supports nullable types.
Namespace: System.Data
Assembly: System.Data.DataSetExtensions (in System.Data.DataSetExtensions.dll)
Type Parameters
- T
A generic parameter that specifies the return type of the column.
Parameters
- row
- Type: System.Data.DataRow
The input DataRow, which acts as the this instance for the extension method.
- columnName
- Type: System.String
The name of the column to return the value of.
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type DataRow. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).| Exception | Condition |
|---|---|
| InvalidCastException | The value type of the underlying column could not be cast to the type specified by the generic parameter, T. |
| IndexOutOfRangeException | The column specified by columnName does not occur in the DataTable that the DataRow is a part of. |
| NullReferenceException | A null value was assigned to a non-nullable type. |
The DataSet class represents null values with the Value instance of the DBNull class. A Language-Integrated Query (LINQ) expression that accessed a column with a null value would generate a InvalidCastException at run time. Additionally, DataSet does not support nullable types. The Field method provides support for accessing columns as nullable types. If the underlying value in the DataSet is Value, the returned nullable type will have a value of null.
If the value of the specified DataColumn is null and T is a reference type or nullable type, the return type will be null. The Field method will not return Value.
The Field method does not perform type conversions. If type conversion is required, you should first obtain the column value by using the Field method. The column value should then be converted to another type.
Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
