What is a Lead selection?

[Former Member]

Hi Friends,

I am a layman in WDA. I would like to know what is Lead selection and in which case we use it.

[Former Member · Accepted solution]

Hi,

For more information go through this article.

https://www.sdn.sap.com/irj/sdn/go/portal/prtroot/docs/library/uuid/60730016-dbba-2a10-8f96-9754a865...

And excellent blog by Thomas szues on Basic concepts of Lead Selection and selection.

[Former Member · Accepted solution]

Hi Suman,

The PDF file which you mentioned was very nice, it clearly explains about the Lead selection. Can you please provide me the link to other documents available for WDA.

Thanks.

[Former Member · Accepted solution]

Hi,

Please check this link,some of the basic tutorials and articles are given there.

https://www.sdn.sap.com/irj/sdn/wiki?path=/display/wdabap/referencesandLinks

If you want any document/article/blog type the relevant in Advanced Search in the SDN site.

[Former Member]

Thanks all for a nice explanation

[uday_gubbala2]

Hi,

Please find the below explanation from the standard SAP learning material,

"A node's element collection can be accessed using a 1-based index value. Exactly one element of the node collection can be marked as the element at lead selection. The lead selection of a context node points to either a single selected node element (value of the lead selection = number of the selected

node element) or, if no element is selected, it has the value of the constant IF_WD_CONTEXT_NODE=>NO_SELECTION. The lead selection can be set automatically by the Web Dynpro framework if the context node property Initialize Lead Selection is set to true. In this case, the first element in a collection will automatically be marked as the element at lead selection. The lead selection can also be set by program source code or it can be set by user actions related to UI elements for example, mark line in table view element, which is bound to the node).

If the lead selection is set, the following is true:

1) In the controller code, special methods can be used to access the lead selection of a node, as well as its position.

2) UI elements such as input fields can be bound to the attributes of this element.

Web Dynpro follows the principle of lazy data instantiation. This means that data is only created when it is actually needed. When this principle is applied to the context architecture, it means that unless the program actually needs to look at the data in a child node, the child node will remain unprocessed. Hence, there is no need to hold multiple instances of data the user has not requested. Lazy data instantiation also means that dependent collections are not automatically created for all elements of the parent node. The creation of a collection of the dependent node is delayed to the point when the related element of the parent collection gets the lead selection.

If you set the Lead Selection property for a table then the element at the lead selection in the context

node becomes the highlighted row when displayed on the screen."

Regards,

Uday

[Former Member]

hi,

Exactly one element of the node collection is highlighted as the lead selection. The lead selection of a context node points to either a single selected node element (value of the lead selection = number of the selected node element) or it has the value of constants IWDNode.NO_SELECTION, if no node element is selected.

Look for the the following links.

It explains lead selection in detail.

http://help.sap.com/erp2005_ehp_03/helpdata/EN/f1/94384162316532e10000000a1550b0/frameset.htm

I hope this will make things clearer to you.

Thanx

[raja_narayanan2]

Hi.....

The lead selection is extremely important with in the nested context structure. The lead selection defines which element of the context is ultimately accessed at runtime.

Lead selection is initialized automatically for each newly created context node.

Thanks & Regards

Raja