AsInterface Method

Overview

The AsInterface method returns a live, strongly-typed view of a data row as a POCO interface. Any change made through the returned interface is immediately propagated to the underlying IDataRow, and any change in the row is visible through the interface.

This method is a cornerstone of the POCO DataSet philosophy of programming to interfaces. It allows application code to work with domain-oriented interfaces instead of dictionary-style row access while still preserving full change tracking.

Declaration

/// <summary>
/// Gets "live" data row as an interface
/// </summary>
/// <typeparam name="TInterface">POCO interface type</typeparam>
/// <param name="dataSet">Data set</param>
/// <param name="tableName">Table name</param>
/// <param name="rowIndex">Row index</param>
/// <returns>"Live" data row as an interface</returns>
/// <exception cref="KeyNotFoundException">Exception is thrown if dataset does not contains a table with specified name</exception>
/// <exception cref="ArgumentOutOfRangeException">Exception is thrown if table does not have row with specified index</exception>
public static TInterface? AsInterface<TInterface>(this IDataSet? dataSet, string tableName, int rowIndex) where TInterface : class

Namespace and Assembly

Namespace: PocoDataSet.Extensions
Assembly: PocoDataSet.Extensions.dll

Behavior

• If dataSet is null, the method returns default(TInterface).
• The method locates the table by name and retrieves the row at the specified index.
• The returned object is a dynamic proxy over the underlying IDataRow, created by DataRowExtensions.AsInterface.
• Property getters and setters on the interface directly read from and write to the data row.

Usage Example

Assume there is an interface describing an employment type:

/// <summary>
/// Defines employment type functionality
/// </summary>
internal interface IEmploymentType
{
  int Id { get; set; }
  string Code { get; set; }
  string? Description { get; set; }
}

The interface can be used to read and modify row data directly:

// 1. Create an empty data set
IDataSet dataSet = DataSetFactory.CreateDataSet();

// 2. Create a table from the POCO interface
IDataTable table = dataSet.AddNewTableFromPocoInterface("EmploymentType", typeof(IEmploymentType));

// 3. Add a row
IDataRow row = table.AddNewRow();
row["Id"] = 1;
row["Code"] = "ET01";
row["Description"] = "Full Time";

// 4. Access the row as a strongly-typed interface
IEmploymentType employmentType = dataSet.AsInterface<IEmploymentType>("EmploymentType", 0);

// 5. Modify data through the interface
employmentType.Code = "ET02";

// 6. Changes are reflected in the underlying row
string updatedCode = (string)row["Code"];

Notes

• AsInterface does not create a copy of the data. It exposes a live projection over the row.
• This method complements IDataTable.AddNewTableFromPocoInterface and DataRowExtensions.AsInterface to enable fully interface-driven data access.

 

Table of Content POCO DataSet DataSet Members

 

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Business Process Programming in .Net
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