Материал: grid
An Easy Reference for ALV Grid Control
The
event
“
data_changed
” makes you aware about F4 functions. It sets the appropriate parameter
from the group with respect to where it was triggered. These parameters are {
E_ONF4,
E_ONF4_BEFORE, E_ONF4_AFTER
}.
Linking F1 Help to Fields
To link your own F1 help to a field, you should simply utilize the event “
onf1
”. At this point, it is
assumed that you know how to define, implement and register an event. The event has following
parameters at its interface:
¾
E_FIELDNAME
of type
LVC_FNAME
¾
ES_ROW_NO
of type
LVC_S_ROID
¾
ER_EVENT_DATA
reference to type
CL_ALV_EVENT_DATA
And, here is a simple sample code for the method.
METHOD handle_on_f1 .
PERFORM f1_help USING e_fieldname es_row_no .
er_event_data->m_event_handled = 'X' .
ENDMETHOD
.
Code Part 35 -
A sample code for the event”onf1”
Here we set the attribute “
er_event_data->m_event_handled
” to prevent further processing of
standard F1 help.
Linking F4 Help to Fields
For the last section, we will deal with linking F4 help to fields. It is easy. As usual, define, implement
and register the event “
onf4
” at proper places in your code. For F4 help, you must register the fields
whose F4 request will trigger the “
onf4
” event. For this you must prepare a table of type “
LVC_T_F4
” and
register this table using the method “
register_f4_for_fields
”. While preparing table you must
include a line for each field which will trigger F4 event. For each field in the structure;
¾
Pass the fieldname to ‘
FIELDNAME
’
¾
Set
‘
REGISTER
’ to make the field registered,
¾
Set
‘
GETBEFORE
’ to provide field content transport before F4 in editable mode
¾
Set
‘
CHNGEAFTER
’ to make the data changed after F4 in editable mode.
© 2005 SAP AG
51
An Easy Reference for ALV Grid Control
DATA: lt_f4 TYPE lvc_t_f4 WITH HEADER LINE .
.. ..
lt_f4-fieldname = 'PRICE'.
lt_f4-register = 'X' .
lt_f4-getbefore = 'X' .
APPEND lt_f4 .
CALL METHOD gr_alvgrid->register_f4_for_fields
EXPORTING
it_f4 = lt_f4[] .
Code Part 36 –
Preparing table for the fields to be registered to trigger F4 event
METHOD handle_on_f4 .
PERFORM f4_help USING e_fieldname es_row_no .
er_event_data->m_event_handled = 'X' .
ENDMETHOD .
Code Part 37 –
A sample “onf4” method implementation
Again, we set the attribute “
er_event_data->m_event_handled
” to prevent further processing of
standard F4 help.
© 2005 SAP AG
52
An Easy Reference for ALV Grid Control
A Piece of Troubleshooting
No Question
Answer
1
I register my local class as the
event handler for all ALV
instances. How can it be known
which instance evokes the
handler?
As a property of ABAP OOP, you can use
the predefined parameter “
sender
” in the
event interface. This parameter refers to
the caller instance.
2
When I wanted to filter with
respect to a field, it couldn’t
handle it. There were matching
records but it didn’t retrieve
them.
The most probable problem is that you
are trying to filter a text field and since
you didn’t set the “
lowercase
” property
at the field catalog, ALV just looks for the
upper case. Set this property for that field
while generating the field catalog.
3
I make some style settings to
individual rows or cells before I
call first display method.
However, I can’t get the result
as I want.
Follow all the steps described in related
sections.
1. You may have forgotten to call
“
set_ready_for_input
” if you are
talking about making cells editable.
2. There may be a filter which makes the
row of styled cell invisible or a sorting
may have changed the order of the
row making it somewhere downwards
so that you can’t realize it.
4
The event “
data_changed
” is
not triggered
You should have not called the method
“
register_edit_event
” by which you
also select the way ALV Grid perceives
changes
5
My function buttons are not
visible on the toolbar
You should have forgotten to call the
method “
set_toolbar_interactive
”.
6
Can I modify the grid title during
execution?
Yes. Use the method “
set_gridtitle
”.
7
I want to add a pushbutton with
an icon for a column. Can I do
that?
Yes. Set the property ‘
ICON
” for the
column to ‘X’ at the field catalog. Then do
the style setting as to make it pushbutton.
Pass the icon name to the field as its
content.
8
Can I hide the header?
Yes. Set the property “
no_headers
” of
the layout structure to ‘X’.
9
Can I hide the ALV toolbar?
Yes. Set the property “
no_toolbar
” of
the layout structure to ‘X’.
10
It cannot find my local class on
the line where I declare my
event handler reference
variable. When I take my class
definition above data
declarations, then variables are
not recognized.
Before your global data definitions, make
the interpreter be aware that your local
class is defined somewhere in your
program. For this, use
“
CLASS <class> DEFINITION DEFERRED
”
or simply make your definitions related to
this class after it is included.
11
Can I display hierarchical lists
using the ALV Grid Control?
No. ALV Grid Control does not support
hierarchical lists.
© 2005 SAP AG
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An Easy Reference for ALV Grid Control
12
I made an editable ALV Grid
and I am utilizing
“
data_changed
” event to
control the data input. However,
I got log entries some of which
exist there although they are
corrected. Is there a refresh
problem? Where?
Exactly. Use the method
“
REFRESH_PROTOCOL
” of the instance
came via the parameter at appropriate
place to overcome.
13
I utilize
“
print_top_of_page
” event.
However, at preview, it sets the
line size to the maximum of 80
and the list size. How can I
overcome this?
Its line-size is restricted so. Try to change
your page header layout.
14
Does the ALV Grid Control
support Drag & Drop?
At other than SAPGUI for HTML
interfaces, the ALV Grid control supports
Drag & Drop. However, this topic was not
included in the context of this tutorial.
15
Displayed columns are not as I
programmed
Check whether a display variant is
activated. If this is not the reason, inspect
your field catalog again.
Author Bio
Serdar
Ş
im
ş
ekler
is an SAP application developer working for
Havelsan Inc.,
Turkey
. He has experience with ABAP program development. He is also studying for
an M.A. degree at the department of philosophy at METU.
© 2005 SAP AG
54