CreateChangeset Method

Overview

The CreateChangeset method creates a new data set that contains only the rows that have been changed in the current data set. A row is considered "changed" when its DataRowState is Added, Modified, or Deleted.

The returned data set (the "changeset") contains only the tables that have at least one changed row. Each included table is created with the same column metadata as the source table, and then the changed rows are copied into the changeset.

Declaration

/// <summary>
/// Creates a "delta changeset" dataset.
/// - Added rows: full row values (same as CreateChangeset).
/// - Modified rows: only primary key columns + __ClientKey (if present) + changed columns.
/// - Deleted rows: only primary key columns + __ClientKey (if present).
/// </summary>
/// <param name="dataSet">Data set.</param>
/// <returns>Delta changeset data set, or null if source is null</returns>
public static IDataSet? CreateChangeset(this IDataSet? dataSet)

Namespace and Assembly

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

Behavior

• If dataSet is null, returns null.
• Iterates through all tables in dataSet.Tables and collects rows whose DataRowState is Added, Modified, or Deleted.
• For each table that has at least one changed row:
  • Creates a table with the same name in the changeset.
  • Copies the source table's column metadata.
  • Copies values of each changed row into a new row in the changeset.
• Deleted rows require special handling because DataTable.AddRow disallows adding a row that is already in Deleted state:
  • The method adds the copied row as a "loaded (unchanged) row.
  • Then it marks the row as deleted at table level.
• For Added and Modified rows, the method preserves the state by setting targetRow.DataRowState and then adding the row to the target table.
• Rows in Added state contain all columns.
• Rows in Modified state contain only primary key columns, the special __ClientKey column (if present), and the columns that have changed.
• Rows in Deleted state contain only primary key columns and the special __ClientKey column (if present).

Usage Example

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

// 2. Create data table with one row in Added state
IDataTable departmentDataTable = dataSet.AddNewTable("Department");
departmentDataTable.AddColumn("Id", DataTypeNames.INT32);
departmentDataTable.AddColumn("Name", DataTypeNames.STRING);

IDataRow departmentDataRow = departmentDataTable.AddNewRow();
departmentDataRow["Id"] = 1;
departmentDataRow["Name"] = "Reception";

// 3. Create data table with one row in Modified state
IDataTable employmentTypeDataTable = dataSet.AddNewTable("EmploymentType");
employmentTypeDataTable.AddColumn("Id", DataTypeNames.INT32);
employmentTypeDataTable.AddColumn("Code", DataTypeNames.STRING);
employmentTypeDataTable.AddColumn("Description", DataTypeNames.STRING);

IDataRow employmentTypeDataRow = employmentTypeDataTable.AddNewRow();
employmentTypeDataRow["Id"] = 1;
employmentTypeDataRow["Code"] = "ET01";
employmentTypeDataRow["Description"] = "Full Time";
employmentTypeDataRow.AcceptChanges();
employmentTypeDataRow["Description"] = "Part Time";

// 4. Create data table with one row that will be deleted
IDataTable employeeDataTable = dataSet.AddNewTable("Employee");
employeeDataTable.AddColumn("Id", DataTypeNames.INT32);
employeeDataTable.AddColumn("FirstName", DataTypeNames.STRING);
employeeDataTable.AddColumn("LastName", DataTypeNames.STRING);

IDataRow employeeDataRow = employeeDataTable.AddNewRow();
employeeDataRow["Id"] = 1;
employeeDataRow["FirstName"] = "Sara";
employeeDataRow["LastName"] = "Gor";
employeeDataTable.AcceptChanges();
employeeDataRow.Delete();

// 5. Build a changeset that contains only changed rows:
// - Department table: 1 Added row with both Id and Name fields
// - EmploymentType table: 1 Modified row with Id and changed Description field
// - Employee table: 1 Deleted row with only Id field
IDataSet? changeset = dataSet.CreateChangeset();

Notes

• The changeset is typically used as an input for persistence layers (for example, to send only changes to a server or to a SQL adapter).
• Unchanged rows are not included in the changeset. Tables with no changes are not included either.
• The returned data set contains copied values; it does not share row instances with the source data set.

 

Table of Content POCO DataSet DataSet Members

 

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Business Process Programming in .Net
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