About the meaning of the first two $symbols of SAP ui5 parameter $$updategroupid

my SAP UI5 course ,SAP UI5 Application development tutorial 65 - be based on OData V4 Of SAP UI5 How to create a table control , Edit and save functions , It demonstrates how to pass XML View mode , Not SAP UI5 Table Control , Syntax for defining compound binding paths , As shown in the figure below ：

<Table
							id="peopleList"
							growing="true"
							growingThreshold="10"
							items="{
								path: '/People',
								parameters: {
									$count: true,
									$$updateGroupId : 'peopleGroup'
								}
							}">

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The semantics of this line is ： When users modify (update) Table row item , The table control does not immediately change these changes , adopt HTTP Post Send the request to the provider OData Service Mock Server, Instead, delay until the user clicks on the toolbar Save Button HTTP Post Batch request , Save the modification .peopleGroup yes Batch Requested group Number , Can be in Chrome Observed in developer tools ：

Have friends for XML Parameters in the view $$updateGroupId Ask such questions ：

This updateGroupId There are two in front

Symbol , and count In front is a

, Can you explain this meaning ？ When is a , When are two ？

The answer is simple ：

1. with Single $ Operation of symbols , On behalf of this is OData Standard operations supported by the protocol .

from OData Agreed Official website A list of all these standard operations can be found on the , such as ：

• $search
• $filter
• $count
• $orderby
• $skip
• $top wait .

With two $$ The beginning of the operation , That is the SAP Imported custom parameters , For the same OData Protocol standard operation .

This truth is actually similar to SAP UI5 index.html In the page ,id by sap-ui-bootstrap The boot script Element , A large number of data-sap-XXXX The same goes for attribute definitions . These attributes are represented by data-sap start , Also to avoid and HTML The possibility of conflicting properties of standards .

OData V4 The model supports read, update and delete Operations specify different group ID. call OData Model API Submitted change request , Will be based on group ID Merge into the same batch request .

About group id More details about the fields , Please refer to these two articles ：

• About SAP UI5 Context.prototype.delete Method Group ID The details of the
• SAP UI5 OData V4 How the model is constructed