dynamic modification at run time

7/27/2019 Dynamic modification at run time

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Dynamic

Modificationsat Runtime


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SAP AG 2005, ABAP Web Dynpro

z Introduction

z Modifying the context structure at runtime

z Modifying the UI Element hierarchy at runt ime

z The use of dynamic actions

Contents:

Dynamic Modifications at Runtime


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Dynamic Modifications at Runtime: Objectives

Af ter completing th is lesson, you will be able to:

z Understand what dynamic programming is

z Dynamically modify and create UI elements

z Dynamically create context elements

z Dynamically bind UI element values to context

elements

z Dynamically create actions


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Dynamic Runtime ModificationsUp till now, we have looked exclusively at the declarative approach to Web Dynpro

programming. Now, we will turn our attention to the programmatic techniques

needed to perform programmatically, the steps that have so far, only been done

declaratively.


Dynamic Runtime Modifications

What is type of dynamic modifications can be made at

runtime?

Dynamic Context ManipulationThe creation, modification and deletion of context nodes andattributes

Dynamic UI ManipulationThe creation, modification and deletion of UI elements

Dynamic Assignment of Act ions to UI Elements


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Dynamic Runtime ModificationsUsually, you would declare the structure of a controllers context at design time,

and then create a static UI layout to display the data contained within the declared

context.

However, it is perfectly possible to create a context and UI layout hierarchy at

runtime. These techniques should only be used when they are required!

It is preferable to create as much of your context and UI layout hierarchy as

possible at design time.


Dynamic Runtime Modifications

There are several situations in which type of coding could berequired:

When the structure of your data is not known until runtime

When you want the behaviour of a screen to be generic andtherefore dynamic

When you are writing utility components that must function ina generic manner

Etc

Under what circumstances should I write coding that

performs dynamic modifications?


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WDDOMODIFYVIEW

This Standard Hook method is called just before the view layout is rendered. It is

the only method in which the programmer is allowed direct access to the UI

element objects themselves.

The FI RSTTI ME parameter is a boolean value that lets you know if the screen is

being rendered for the very first time, or re-rendered in response to an Action

event.


Standard Hook Method View controller

Only a view controller has these hook methods.

The method WDDOMODIFYVIEW will only be called i f:

The view is part of the current view assembly and this is the

first time the view is required, or

The view is part of the current view assembly and an action

belonging to the same view controller has been processed.


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Dynamic Context Data Creation

Example of context

metadata to be created

dynamically?Context Root (c=1..1, s=true)FLIGHTS (c=0..n, s=true)

Context Metadata to be

created at runtime

BOOKINGS (c=0..n, s=false)

PRICE

CARRID

CONNID

FLDATE

BOOKID

CUSTOMID

CLASS

PASSNAME


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Context node creationAll context nodes created by the application developer must have some other

node acting as their parent. This is why a context is always supplied containing a

root node. The root node is the anchor point for all other nodes, irrespective of

whether they created statically at design time, or dynamically at runtime.

Node creation principle

1.Create the nodes metadata

2.Create the node instance based on the new metadata


Coding steps:

Obtain a reference to the metadata ofthe context node that will act as the new

nodes parent. In this case, we are

creating an independent node, therefore

we get a reference to the metadata of

the root node.

Call static method

create_nodeinfo_from_struct( ) from

helper class cl_wd_dynamic_tool

A DDIC Structure can be used for the

attribute creation.

Dynamic Value Node Creation (1)

Context Root (c=1..1, s=true)

FLIGHTS (c=0..n, s=true)

Context Metadata to be

created at runtime

BOOKINGS (c=0..n, s=false)

PRICE

CARRID

CONNID

FLDATE

BOOKID

CUSTOMID

CLASS

PASSNAME

DDIC Structure SFLIGHT


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Creating an value node

We are now dealing with the structure of the context not the contents, therefore we

must work with the metadata that describes the context nodes and attributes,

rather than the runtime data contained within node collections. This means we will

be working with if_wd_context_node_info objects.

1.Get a reference to the metadata of the node acting as the parent of the new node.

2.Use method create_nodeinfo_from_struct from helper class cl_wd_dynamic_tool to create a

node from a structure.


Dynamic Node Creation related to a structure

Coding steps:

Obtain a reference to the metadata of the context node that will act as the

new nodes parent.

Call static method create_nodeinfo_from_struct( ) from helper c lass

cl_wd_dynamic_tool to create from a DDIC structure a node.

DATA: rootnode_info TYPE REF TO if_wd_context_node_info,

table_name type string value 'SFLIGHT',

node_name type string value 'CONNECTIONS'.

* get root node info of context

rootnode_info = wd_context->get_node_info( ).

* create node named CONNECTIONS of sflight

cl_wd_dynamic_tool=>create_nodeinfo_from_struct(

parent_info = rootnode_info

node_name = node_name

structure_name = table_name

is_multiple = abap_false

is_mandatory = abap_true ).Cardinality 11


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Dynamic Sub Node Creation related to a structure

DATA: dyn_node type ref to if_wd_context_node,

dyn_node_info TYPE REF TO if_wd_context_node_info,

. . .

* navigate from to via lead selection

dyn_node = wd_Context->get_Child_Node( Name = node_name ).

dyn_node_info = dyn_node->get_node_info( ).

* create sub node named BOOKINGS of sbook


parent_info = dyn_node_info

node_name = 'BOOKINGS'

structure_name = 'SBOOK'

is_multiple = abap_false

is_mandatory = abap_true ).


FLIGHTS (c=0..n, s=true)

BOOKINGS (c=0..n,s=false)

PRICE

CARRID

CONNID

FLDATE

BOOKID

CUSTOMID

CLASS

PASSNAME

Structure SBOOK

Coding steps:

Obtain a reference to node and reference to the

metadata of the context node that will act as the new

nodes parent

Call static method create_nodeinfo_from_struct( ) to

create from a DDIC structure a node


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Add a Dynamic Attribute to a Node


UI_ATTRIBUTES

BUTTON_VISIBILITY

TEXT_VISIBILITY

* add context attribute to node

data: Ui_Attributes_info type ref to If_Wd_Context_Node_info.

data: ls_att type WDR_CONTEXT_ATTRIBUTE_INFO.

* get node info of context

Ui_Attributes_info = Node_Ui_Attributes->get_node_info( ).

ls_att-name = `TEXT_VISIBILITY`.

ls_att-TYPE_NAME = 'WDUI_VISIBILITY'.

Ui_Attributes_info->add_attribute( ATTRIBUTE_INFO = ls_att ).

Coding steps:

Obtain a reference to the metadata of the parent node

that will contain the attribute

Fill structure ( WDR_CONTEXT_ATTRIBUTE_INFO )

with attribute properties

Add at tr ibute to parent node


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Principles of UI element manipulation

The following coding principles must be adhered to during UI element

manipulation:

1. Only perform direct manipulation of UI element objects when it is notpossible to control their behaviour through context binding.

2. UI manipulation is only permitted within the wdDoModi f yVi ew( )

method of a view controller.

3. wdDoModi f yVi ew( ) has a boolean parameter called f i r st Ti me.

Typically, you will only build a dynamic UI element hierarchy whenf i r st Ti me == true. This avoids rebuilding the UI element hierarchy

unnecessarily.

4. Do NOT implement any coding in wdDoModi f yVi ew( ) that modifies

the context! The context should be considered read-only during theexecution of this method.


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Dynamic UI manipulation (1)

Context Root

Connections

PRICE

CARRID

CONNID

FLDATE

Context Metadata UI Element Hierarchy to

be created at runtime

RootUIElementContainer

CARRIDLabel

CARRIDInput

CONNIDLabel

CONNIDInput

FLDATELabel

FLDATEInput

PRICELabel

PRICEInput


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Coding steps:

Create a new InputField UI

element object (bind to

context attribute

Create a new Label UI

element object

Set the Labels properties

as required

Add the Label object to the

UI element container

Set the InputFields

properties as required

Add the InputField to the

UI element container

InputField

UI Element Hierarchy to



InputField

Label

Label

bind

add

Context Root

Connections

PRICE

CARRID

CONNID

FLDATE

Context Metadata


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* Create label and input field

** create a input field

wd_input_field = cl_wd_input_field=>new_input_field( view = view

bind_value = 'CONNECTIONS.CARRID').

** create a label for the input field

wd_label = cl_wd_label=>new_label( label_for = wd_input_field->id ).

** set matrix_head_data for the label

cl_wd_matrix_head_data=>new_matrix_head_data( element = wd_label ).

** add label to container

wd_container->add_child( wd_label ).


cl_wd_matrix_data=>new_matrix_data( element = wd_input_field ).

** add input field to container

wd_container->add_child( wd_input_field ).



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Dynamic Actions

Certain UI elements can trigger client-side events (e.g. pressing enterin an I nput Fi el d, toggling a CheckBox or selecting the row of a

table).

In order for the client-side event to trigger the execution of a server-

side method, Web Dynpro uses the concept ofActions.

Actions can either be assigned declaratively to UI element events at

design time, or dynamically at runtime.

Actions assigned dynamically can only refer to existing server-side

action handler methods. It is not possible to define the coding of an

action event handler dynamically; only to define which existing actionhandler will be called when a client-side event is trapped.


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The action can only be declared at design time.


Action Declaration

Declared action

Coding required

for dynamic

assigned action


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A button can be created and be added to the UI element container.


* Create button** create button UI element

wd_button = cl_wd_button=>new_button( text = 'Show Flights'

on_action = 'SELECT_FLIGHTS' ).


cl_wd_matrix_head_data=>new_matrix_head_data( element = wd_button ).

** add button to container

wd_container->add_child( wd_button ).

Create a Dynamic Button

Coding steps:

Create a new Button UI

element object (assign an

predefined action)

Set the But ton properties

as required

Add the But ton to the UI

element containerButton

UI Element Hierarchy to



InputField

Label

Context Root

Connections

PRICE

CARRID

CONNID

FLDATE

Context Metadata

Button


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Was this a good approach?

Development Principle

Only if the required functionality of your application does notpermit design time declarations, then use a dynamicmodification approach.

Al l context node/attribute and UI elements which can becreated during design time should be created during designtime.


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Example for Dynamic Programming

Display the content of

ANY table

Dynamic Context

Dynamic table UI element

Dynamic data retrieval


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Example for Dynamic Programming I

DATA:

group_1 TYPE REF TO cl_wd_uielement_container,

new_tab TYPE REF TO cl_wd_table,

dyn_node TYPE REF TO if_wd_context_node,

tabname_node TYPE REF TO if_wd_context_node,rootnode_info TYPE REF TO if_wd_context_node_info,

stru_tab TYPE REF TO data,

tablename TYPE string.

FIELD-SYMBOLS TYPE table.

* get node info of context root node

rootnode_info = wd_context->get_node_info( ).

* Get the name of the table to be created

tabname_node = wd_context->get_child_node( name = 'TABLE_DATA' ).

tabname_node->get_attribute( EXPORTING name = 'NAME' IMPORTING value =

tablename ).translate tablename to upper case.

* create sub node of structure (tablename)


parent_info = rootnode_info

node_name = tablename

structure_name = tablename

is_multiple = abap_true ).


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Example for Dynamic Programming II

* remove "old" table UI element from view , if necessary

group_1 ?= view->get_element( 'GROUP_1' ).

group_1->remove_child( id = 'TESTTAB' ).

* * get instance of new node

dyn_node = wd_context->get_child_node( name = tablename ).

DATA new_tab TYPE REF TO cl_wd_table.

* create new UI element table

new_tab = cl_wd_dynamic_tool=>create_table_from_node(

ui_parent = group_1

table_id = 'TESTTAB'

node = dyn_node ).

** fill context node with data

* create internal table of (tabletype)CREATE DATA stru_tab TYPE TABLE OF (tablename).

ASSIGN stru_tab->* TO .

* Get table content

SELECT * FROM (tablename) INTO CORRESPONDING FIELDS OF TABLE .

* Bind internal table to context node

dyn_node->bind_table( ).


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You should now be able to:

z Understand what dynamic programming is

z Dynamically modify and create UI elements

z Dynamically create context elements

z Dynamically bind UI element values to context

elements

z Dynamically create actions

Web Dynpro Dynamic Programming: Summary


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SAP AG2005

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