webdynproabappart1.pdf

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Sankara rao BhattaSAP application developer

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Developments using Web Dynpro for ABAP

Part I

(Extracting the data from a Table)

Sankara rao Bhatta

SAP application developer

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The purpose of this submission is to provide the basic idea and framework on Web

Dynpro ABAP developments, for the people who want to excel in this field. This is

particularly useful for the people who had working experience in ABAP OOPs and want

to learn Web Dynpro ABAP.

This submission is part of series of developments which are done in the WL0 system.

This is the first submission in this series, where extracting the data form a table has been

explained in detail.

The development involves two steps.

1) Creation of a table YMOVIE to store the data.

2) Developing a web dynpro application in order to extract the data form the table

and display it in the browser.

I presume that the reader has good knowlwdge on ABAP data dictionary, so I will not go

into the details of the table creation.

The table name is YMOVIE and has 7 fields, which are

1) MANDTclient

2) YYEARYear

3) CATEGORY Category ( The domain for this field has fixed values PIC, ACT

and ACR )

4) WINNERWinner

5) NOMINEE1nominee 1



The table basically stores the oscar award data for different years and categories.

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The domain ZZCAT is shown below

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Now coming to the second and important part of the development, the ABAP workbench( SE80 ) is used to develop the web dynpro component / interface.

Enter the name of the web dynpro component and click on Display button. It will ask

whether to create the new component or not. Click on yes and enter the description for

the new webdynpro component.

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The window name by default is same as name of the web dynpro component, but you can

change it ( In this example it was changed to MAIN ). Save the object as local object.

When you first create a component you will see that some things are automatically

generated by the system. Let us discuss about them in detail.

COMPONENETCONTROLLER

The component controller is a central location for data exchange between different views

of one component. Each Web Dynpro component contains exactly one component

controller. This controller is automatically created during the component creation and

contains a context, events, and methods. the controllers of different component views

can access context elements or methods of the component controller.

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[email protected] tutorialshereThe component controller has several tabs like context, attributes, methods and events

etc.,

The attribute WD_CONTEXT is a reference variable of type

IF_WD_CONTEXT_NODE. This attribute technically refers to the root node of thecontext of the controller. There are several methods available in this interface, which are

used to edit the data held by context nodes.

For example.,

GET_CHILD_NODEthis method retrieves a specific child node.

GET_ATTRIBUTEthis method retrieves the value of a context attribute.

BIND_TABLEThis method binds an internal table to a context node.

Each controller contains a local interface which can be accessed in the controller. The

controller attribute WD_THIS is a reference to this local interface. The methods and

attribute of the local controller interfaces can be accessed using these reference

variables.

Component Interface

Each component has an interface in order to enable communication between Web Dynpro

components and to enable a component to be called up by a user. This interface consists

of two parts:

Interface View of a Window Contained in a Component

The interface view of a Web Dynpro window is used to link a window with a WebDynpro application that can be called by the user. The interface view contains inbound

and outbound plugs. When you create the component, system automatically creates a

inbound plug with the name DEFAULT as a startup plug.

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Interface Controller of a Component

As well as the visual part, the interface of a Web Dynpro component also has aprogrammatic part, the interface controller. This is visible inside and outside of the

component, and performs the program side of the exchange of business data. The

interface controller, like the interface view, is not an independently implemented object.

Instead, the visibility of methods and events of the component controller can be extended

beyond the limitations of the component in question.

A window is used to combine several views. Each window has a uniquely assigned

interface view. This interface view represents the outward view of the window. Theinterface view is linked with a Web Dynpro application so that the window can be called

using a URL.

The window consists of several tabs like inbound and outbound plugs used for navigating

between different windows and its own context, attributes and methods.

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To create a view right click on the component and select create view

Enter the name and description for the view.

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To create elements under the root node, right click and select Insert element.

In the drop down, there are several options like label, button, input field etc.,

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[email protected] tutorialshereWe will create two labels and two input fields for year and category . We will also create

a button with the name search. A table which will display the results based on the year

and category provided in the input fields.

In the property panel of the each element (button, label etc.,), the value entered in the

text field appears as the label on the element.

After the creation of all the above said elements the layout of the view looks something

like this (observe the message in the table element table does not contain visiblecolumns)

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[email protected] tutorialshereTill now we have designed the layout of the view, which is the users view in the

browser. We did not link the fields with any elements of the context, neither we have

written any application logic to fill the table with the data.

There are two types of context, one is context of the component and the other context of

the view. The first one is global to the component and the elements in this context can be

accessed from any of the view. On the other hand the view context is local to the view.

We need to create and link the context elements for the two input fields and the table.

To do this go to the context tab of the COMPONENTCONTROLLER and right click on

context, go to create Attribute.

In the subsequent screen enter the values as shown below

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Similarly create attribute for category field. And for the table we need to create a node

instead of attribute as table contains multiple fields.

For the table node movie enter the YMOVIE in the Dictionary structure field and click

on add attribute from the structure.

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Select the required fields and click on continue.

The context of the COMPONENTCONTROLLER now looks as shown below

Now as we built the context we need to link this attributes and nodes to the corresponding

layout elements. Before this we need to copy this context to the view context. To do this

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[email protected] tutorialshereclick on the view VIEW1 and go to the context tab. Right click on the context and

select copy nodes of different context.

In the next screen , in the field view/controller names enter the

COMPONENTCONTROLLER ( you can do it by hitting F4 button also ) and select

the radio button Do not copy node itself, but attributes and sub nodes only. Select the

context in the next screen and select continue.

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[email protected] tutorialshereThe view context after copying the nodes from the COMPONENTCONTROLLER looks

like this

Now as we built the context of the view it is time to link the context elements with the

layout elements.

In the property panel of the I/O field YEAR_I, there is a row with the name value and

beside that you will find the button for binding the field with the context element.

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When you click on the binding button a new window opens where all the context

elements are listed. For our program purpose we will choose YEAR. Similarly for

CATEGORY_I fields we choose category, for table element we choose the node

MOVIE.

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[email protected] tutorialshereIn case of table we need to further binding between the attributes of the MOVIE node and

the columns of the table. To do this right click on MOVIE table element and select

create binding.

In the next screen select the InputField in the cell editor of table column dropdown

and value in the name of property to be found dropdown.

After finishing the binding the message table does not contain visible columns

disappears from the table elements. If you expand the table node you will find different

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[email protected] tutorialsherecolumns and captions created automatically. Select the captions for each column and

enter the description in the text row.

The layout now appears something like this:

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As we completed the binding part we will move onto building the application logic for

extracting the data from the YMOVIE table based on the selection criteria given. In order

to do that we need to assign an eventhandler method to the button SEARCH. Click on the

button to create an eventhandler method.

Enter the name for action and description to create the evenhandler method.

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Now double click on the ONCLICK action in the property panel of the button to enter

the ABAP editor of the method ONACTIONONCLICK ( the system automatically

adds ONACTION before the name of the action given by the user ).

In order to fetch the records from the table YMOVIE we need to retrieve the values

entered in the fields year and category. The code for this can be generated automatically

by the system using Web dynpro code Wizard ( at the top of the screen ). The code

wizard can be used for several purposes like getting the value from a node or attribute, to

call methods etc. In our case we will use this for extracting the values from the attributes

year and category.

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[email protected] tutorialshereIn the wizard window select read context radio button and using F4 button select

YEAR. Do similarly for category. When we use the code wizard for category attribute

some data declaration code generated is redundant ( declarations ofElem_Context and

Stru_Context). So, we need to comment them in order to pass the syntax check.

The variables Item_Category and Item_year are used to store the values extracted from

the context attributes YEAR and CATEGORY.

In order to access the data from the YMOVIE table we will write a select statement as

shown below

select * from ymovie into corresponding fields of table itab_movie

where yyear = Item_year

and category = Item_Category.

Itab_movie is an internal table of type movie_data, where movie_data is a custom defined

structure.

types: begin ofmovie_data, yyear

type ymovie-yyear, category

type ymovie-category, winner

type ymovie-winner,

nominee1 type ymovie-nominee1,



end ofmovie_data.

After getting the values into internal table itab_movie we need to pass these values to the

context node MOVIE in order to display it in the browser. We achieve this in two steps

- Use GET_CHILD_NODE method of the attribute WD_CONTEXT to instantiate

MOVIE node. We store this reference in TABLE_NODE variable.

- Using the BIND_ELEMENTS method we bind the internal table itab_movie

with the context node MOVIE.

The code which dos the above said two steps is:

TABLE_NODE = WD_CONTEXT->GET_CHILD_NODE('MOVIE' ).

TABLE_NODE->BIND_ELEMENTS( itab_movie ).

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Save the code and activate the whole component. The view VIEW1 must be embedded

into the window MAIN. Right click on the window and select Embed View.

Enter view VIEW1 in the next window by using F4. Save and activate the window

The final step it to create a web dynpro application for accessing this component through

web. This is something similar to the creation of transaction for a module pool program

in classical ABAP. To create a web dynpro application right click on webdynpro

component createweb dynpro application. Enter the description and continue.

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In the properties tab of the web dynpro application a URL is automatically generated by

the system. This URL is used to access the webdynpro application from the web.

To run the application either paste the URL in the IE or right click on web dynpro

application and select test. This will open the application in a browser.

The result as it appears in the IE is shown below.

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The complete code snippet of the method ONACTIONONCLICK is given below:

method ONACTIONCLICK .types: begin ofmovie_data,

yyear type ymovie-yyear,category typeymovie-category,winner typeymovie-winner,nominee1 type ymovie-nominee1,nominee2 type ymovie-nominee2,nominee3 type ymovie-nominee3,end ofmovie_data.

data: itab_movie type table of movie_data.

data:

Elem_Context type ref to If_Wd_Context_Element,

Stru_Context type Wd_This->Element_Context ,

Item_CATEGORY like Stru_Context-CATEGORY.

* get element via lead selection

Elem_Context = wd_Context->get_Element( ).

* get single attribute

Elem_Context->get_Attribute(

exporting

Name = `CATEGORY`

importing

Value = Item_Category ).

data:

* Elem_Context type ref to If_Wd_Context_Element,

* Stru_Context type Wd_This->Element_Context ,

TABLE_NODE type ref to IF_WD_CONTEXT_NODE,

Item_YEAR like Stru_Context-YEAR.

* get element via lead selection

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[email protected] tutorialshereElem_Context = wd_Context->get_Element( ).

* get single attribute

Elem_Context->get_Attribute(

exportingName = `YEAR`

importing

Value = Item_Year ).

select * from ymovie into corresponding fields of tableitab_moviewhere yyear = Item_Year

and category = Item_Category.

TABLE_NODE = WD_CONTEXT->GET_CHILD_NODE('MOVIE' ).

TABLE_NODE->BIND_ELEMENTS( itab_movie).

endmethod.

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Appendix

The complete documentation on webdynpro for ABAP can be found at online sap help:

http://help.sap.com/saphelp_nw04s/helpdata/en/77/3545415ea6f523e10000000a155106/f

rameset.htm

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Sankara rao Bhatta

SAP li i d l
mailto:[email protected]:[email protected]:[email protected]://www.youtube.com/playlist?list=PLCC0722EAC6719F92&feature=plcphttp://www.youtube.com/playlist?list=PLCC0722EAC6719F92&feature=plcphttp://www.youtube.com/playlist?list=PLCC0722EAC6719F92&feature=plcphttp://help.sap.com/saphelp_nw04s/helpdata/en/77/3545415ea6f523e10000000a155106/frameset.htmhttp://help.sap.com/saphelp_nw04s/helpdata/en/77/3545415ea6f523e10000000a155106/frameset.htmhttp://help.sap.com/saphelp_nw04s/helpdata/en/77/3545415ea6f523e10000000a155106/frameset.htmhttp://www.youtube.com/playlist?list=PLCC0722EAC6719F92&feature=plcphttp://www.youtube.com/playlist?list=PLCC0722EAC6719F92&feature=plcphttp://www.youtube.com/playlist?list=PLCC0722EAC6719F92&feature=plcpmailto:[email protected]:[email protected]://www.youtube.com/playlist?list=PLCC0722EAC6719F92&feature=plcphttp://help.sap.com/saphelp_nw04s/helpdata/en/77/3545415ea6f523e10000000a155106/frameset.htmhttp://help.sap.com/saphelp_nw04s/helpdata/en/77/3545415ea6f523e10000000a155106/frameset.htmhttp://www.youtube.com/playlist?list=PLCC0722EAC6719F92&feature=plcpmailto:[email protected]:[email protected]

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