Dapper Plus Identity Propagation

Description

Propagating the identity is often needed when an entity has some relationship without navigation property.

For example, the invoice has invoice items which also hold the InvoiceID value.

In Dapper Plus, there is 3 major ways to propagate the identity:

• Auto Identity Propagation
• AfterAction
• ThenForEach

Auto Identity Propagation

The auto identity propagation is the easiest ways. You simply specify during the mapping that the identity value should be auto propagated (set the second parameter to true).

context.Entity<Invoice>().Identity(x => x.InvoiceID, true);

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However, some restriction applies. The identity must have either one of the those following convention (case insensitive):

• ID, in this case, we will automatically propagate to all properties with the name [EntityType]ID, in our example InvoiceID.
• Or directly [EntityType]ID, in our example InvoiceID.

AfterAction

The AfterAction method allows you during the mapping to specify a custom action to perform after an operation has been made.

DapperPlusManager.Entity<Invoice>().Identity(x => x.InvoiceID)
	.AfterAction((actionKind, invoice) =>
		 {
			 if (actionKind == DapperPlusActionKind.Insert || actionKind == DapperPlusActionKind.Merge)
			 {
				 if (invoice.InvoiceMeta != null)
				 {
					 invoice.InvoiceMeta.InvoiceID = invoice.InvoiceID;
				 }

				 if (invoice.InvoiceItems != null)
				 {
					 invoice.InvoiceItems.ForEach(x => x.InvoiceID = invoice.InvoiceID);
				 }
			 }
		 });

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ThenForEach

The ThenForEach method allows you to make a custom action after a bulk-operation has been made.

connection.BulkInsert(invoices)
		.ThenForEach(invoice => {
			if(invoice.InvoiceMeta != null)
			{
				invoice.InvoiceMeta.InvoiceID = invoice.InvoiceID;
			}
			  
			if(invoice.InvoiceItems != null)
			{
				invoice.InvoiceItems.ForEach(invoiceItem => invoiceItem.InvoiceID = invoice.InvoiceID);
			}
		  })
		.AlsoBulkInsert(x => x.InvoiceMeta)
		.ThenBulkInsert(x => x.InvoiceItems);

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