DoPostSaveMerge Method

Overview

The DoPostSaveMerge method applies a post-save server response (a changeset) to the current data set.

A typical use case is applying server-assigned values such as identity primary keys and concurrency tokens (for example, RowVersion) back to newly added rows on the client.

Declaration

/// <summary>
/// Dose PostSave merge
/// </summary>
/// <param name="currentDataSet">Current data set</param>
/// <param name="refreshedDataSet">Refreshed data set</param>
/// <param name="mergeOptions">Merge options</param>
public static void DoPostSaveMerge(this IDataSet? currentDataSet, IDataSet changesetDataSet, IMergeOptions mergeOptions)

Namespace and Assembly

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

Behavior

• If currentDataSet is null, the method returns without doing anything.
• Merges only the tables/rows present in the post-save changeset into the current data set.
• Matches rows using primary keys when possible, and falls back to __ClientKey correlation when needed.
• Does not require the current data set to be 'clean' (post-save merge is intended to reconcile server-assigned fields after persistence).

Usage Example

// CURRENT: client-side state (a new Department row exists but has no server Id yet).
IDataSet currentDataSet = DataSetFactory.CreateDataSet();

IDataTable currentDepartment = currentDataSet.AddNewTable("Department");
currentDepartment.AddColumn("Id", DataTypeNames.INT32);
currentDepartment.AddColumn("Name", DataTypeNames.STRING);
currentDepartment.AddColumn("RowVersion", DataTypeNames.BINARY);

IDataRow newRow = currentDepartment.AddNewRow();
newRow["Name"] = "Engineering";

// When a new row is created, POCO DataSet assigns a __ClientKey to correlate with server replies.
Guid clientKey = newRow.GetDataFieldValue<Guid>(SpecialColumnNames.CLIENT_KEY);

// POST-SAVE (server response): same row, now with Id and RowVersion assigned.
IDataSet postSaveDataSet = DataSetFactory.CreateDataSet();

IDataTable postSaveDepartment = postSaveDataSet.AddNewTable("Department");
postSaveDepartment.AddColumn("Id", DataTypeNames.INT32);
postSaveDepartment.AddColumn("Name", DataTypeNames.STRING);
postSaveDepartment.AddColumn("RowVersion", DataTypeNames.BINARY);

IDataRow savedRow = postSaveDepartment.AddNewRow();
savedRow["Id"] = 10;
savedRow["Name"] = "Engineering";
savedRow["RowVersion"] = new byte[] { 1, 0, 0, 0, 0, 0, 0, 0 };
savedRow[SpecialColumnNames.CLIENT_KEY] = clientKey;

IMergeOptions options = new MergeOptions();

// Apply post-save response to CURRENT.
currentDataSet.DoPostSaveMerge(postSaveDataSet, options);

// After merge, CURRENT row contains server-assigned Id and RowVersion.
int id = currentDepartment.Rows[0].GetDataFieldValue<int>("Id"); // 10
byte[]? rv = currentDepartment.Rows[0].GetDataFieldValue<byte[]>("RowVersion"); // {1,0,0,0,0,0,0,0}

Notes

• Post-save merge is a good fit for applying a server response after SaveChanges.
• If your persistence layer returns only a delta changeset, you can merge it back without reloading the full dataset.

 

Table of Content POCO DataSet DataSet Members

 

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Business Process Programming in .Net
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