ToDetachedList Method

Overview

The ToDetachedList extension method converts all rows of data table into a list of detached interface objects. Each returned object represents a snapshot of the row values at the moment the method is called.

Detached objects are not connected to the data table after creation. Snapshot proxy properties are read-only. Attempting to assign to a property throws NotSupportedException. Reading a property returns the captured value, and subsequent changes to the data table are not reflected in the detached objects.

Declaration

/// <summary>
/// Returns observable data table as a detached list
/// </summary>
/// <typeparam name="TInterface">The interface type describing the table's row contract.</typeparam>
/// <param name="observableDataTable">Observable data table</param>
/// <returns>Observable data as a detached list</returns>
public static TInterface[] ToDetachedList<TInterface>(this IObservableDataTable? observableDataTable) where TInterface : class

/// <summary>
/// Returns observable data table as a detached list
/// </summary>
/// <typeparam name="TInterface">The interface type describing the table's row contract.</typeparam>
/// <param name="observableDataTable">Observable data table</param>
/// <param name="nameMap">Name map</param>
/// <returns>Observable data as a detached list</returns>
public static TInterface[] ToDetachedList<TInterface>(this IObservableDataTable? observableDataTable, IDictionary<string, string> nameMap) where TInterface : class

Namespace and Assembly

Namespace: PocoDataSet.ObservableExtensions
Assembly: PocoDataSet.ObservableExtensions.dll

Behavior

• Iterates over all rows in the data table.
• Creates a detached snapshot proxy for each row.
• Copies current row values into the detached object.
• Returns an list containing the detached objects in row order.
• Returns an empty list when dataTable is null.

Usage Example

Assuming that there is an interface IEmploymentType, which defines employment type functionality:

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

// 1. Create observable data set
IObservableDataSet observableDataSet = new ObservableDataSet();

// 2. Create Department observable table with row
IObservableDataTable employmentTypeObservableDataTable = observableDataSet.AddNewTable("EmploymentType");
employmentTypeObservableDataTable.AddColumn("Id", DataTypeNames.INT32);
employmentTypeObservableDataTable.AddColumn("Code", DataTypeNames.STRING);
employmentTypeObservableDataTable.AddColumn("Description", DataTypeNames.STRING);

IObservableDataRow employmentTypeObservableDataRow1 = employmentTypeObservableDataTable.AddNewRow();
employmentTypeObservableDataRow1["Id"] = 1;
employmentTypeObservableDataRow1["Code"] = "ET01";
employmentTypeObservableDataRow1["Description"] = "Part Time";

// 4. Call ToDetachedList method to get an list of snapshot (read-only) proxies
List<IEmploymentType> employmentTypes = employmentTypeObservableDataTable.ToDetachedList<IEmploymentType>();

// 4. Verify that employment type is detached (read only) by attempting to modify a property
// This line throws NotSupportedException
employmentTypes[0].Code = "ET99"

Notes

• Detached objects are suitable for snapshot scenarios such as export or background processing.
• No runtime linkage is preserved between returned objects and the data table.
• The snapshot reflects the state of the table at the time the method is called.

Table of Content POCO DataSet Observable Data Table Members

 

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Business Process Programming in .Net
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