Access via NULL reference object not possible

Question

Hi friends,
  I have created an wda application which uses the table popin to display data.
  So that i have created a view with two of the  fields as link to action UI element.
  In the Events/Actions of the link to action element i implemented the following logic.
  data wd_table_cell_editor type ref to cl_Wd_view_element.
  data wd_table_column      type ref to cl_wd_table_column.
  data wd_popin             type ref to cl_wd_table_popin.
  data id type string.
<b> wd_table_cell_editor ?= wd_this->m_view->get_element( id ).</b>
  wd_table_column ?= wd_table_cell_editor->get__parent( ).
  wd_popin = wd_table_column->get_popin( ).
  context_element->set_attribute( name = 'SELECTED_POPIN' value =
wd_popin->id ).
So when i click on the link to action in the table column of the field am getting the following error
<b>Access via NULL reference object not possible.</b>
While debugging i have noticed that this error was coming at the below step of the code.
<b>wd_table_cell_editor ?= wd_this->m_view->get_element( id )</b>
in the m_view->get_element( id ) does not contan any value , its showing as table , as null value cannnot be assigned may be its throwing the above error.
But i didnt understand why the view is not getting UI element id ....
Can one please suggest me where might be the wrong....
Regards
Sireesha.

Answer 1

Hi nithya,
  Could you please calrify the doubts for the following q's.
1. As u said in the above post, i have changed the code to the below.
     data: lr_table type ref to cl_wd_table,
lr_table_col type ref to cl_wd_table_column.
lr_table ?= wd_this->m_view->get_element( 'TABLE' ).
lr_table_col = lr_table->get_column( ID = 'TABLE_CONNECTID' ).
  <b>wd_popin = lr_table_col->get_popin( ).</b>
(At the above step which is in bold , eventhough there is value in lr_table_col->get_popin , its not assigning a value to the wd_popin, throwing same error NULL etc.,)
  context_element->set_attribute( name = 'SELECTED_POPIN' value =
wd_popin->id ).
2. Before changing the code suggested by u, the follwoing was the code from standard example.Its working fine in the application wdr_test_table.I have debugged the code.The value is getting assigned into wd_table_cell_editor.
The same thing i have done but its failing to assign the value. thats y its throwing null reference error. Here i have a confusion how its assigning a value and y not in the z application.am giving the code below which is in standard and my application.Please clarify these.
data wd_table_cell_editor type ref to cl_Wd_view_element.
  data wd_table_column      type ref to cl_wd_table_column.
  data wd_popin             type ref to cl_wd_table_popin.
  <b>wd_table_cell_editor ?= wd_this->m_view->get_element( id ).</b>
( Note :  wd_this->m_view->get_element contains value but not assigning it to the wd_table_cell_editor and same code in the standard behaving correctly like assigning the view value to the cell editor. Y this behavior, please advice me)
  wd_table_column ?= wd_table_cell_editor->get__parent( ).
  wd_popin = wd_table_column->get_popin( ).
  context_element->set_attribute( name = 'SELECTED_POPIN' value = wd_popin->id )
Regards
Sireesha.