DataRowExtensions.Field<T> Method (DataRow, DataColumn, DataRowVersion)
Provides strongly-typed access to each of the column values in the specified row. The Field<T> method also supports nullable types.
Assembly: System.Data.DataSetExtensions (in System.Data.DataSetExtensions.dll)
Parameters
- row
-
Type:
System.Data.DataRow
The input DataRow, which acts as the this instance for the extension method.
- column
-
Type:
System.Data.DataColumn
The input DataColumn object that specifies the column to return the value of.
- version
-
Type:
System.Data.DataRowVersion
A DataRowVersion enumeration that specifies the version of the column value to return, such as Current or Original version.
Type Parameters
- T
A generic parameter that specifies the return type of the column.
| Exception | Condition |
|---|---|
| InvalidCastException | The value type of the underlying column could not be cast to the type specified by the generic parameter, T. |
| IndexOutOfRangeException | |
| 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 doesn’t support nullable types. The Field<T> 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, then the return type will be null. The Field<T> method will not return Value.
The Field<T> method does not perform type conversions. If type conversion is required, you should first obtain the column value by using the Field<T> method. The column value should then be converted to another type.
Available since 3.5