ABAP Dictionary
Abstract The following section details and describes the ABAP Dictionary.The main purpose of this chapter is to show how to realize all the development objects to be used in the future Web Dynpro applications.Therefore,we present not only the modality to create the various development objects in the ABAP Dictionary, but also the modality to use them in realizing Web Dynpro applications.
We can create development objects in ABAP Dictionary,by using the transaction SE11(ABAP Dictionary Maintenance) or the Object Navigator.
Development object with transaction SE11
ABAP programming language has a number of ten elementary data types that we can use in our programs. When we want to create global data types by using the ABAP Dictionary, we have to use dictionary built-in types. These predefined types are different from the elementary data types. We need them for reasons of compatibility with the external data types.
In this we presented some of the ABAP Dictionary Built-In types and a few corresponding examples of Dictionary built-in data types and ABAPelementary types.
Some of ABAP Dictionary Built-In types and corresponding ABAP elementary types
A data element defines an elementary data type and has certain properties. We create a data element YDATEOFBIRTH
Definition of a data element
In the “Data Type” tab we can choose between the elementary type and reference type. The elementary type can be a domain and a build-in type. In this case, we have chosen the build-in type DATS that has a predefined format (YYYYMMDD) and a predefined length 8.
In the tab “Field Label”, we can set a field label that is automatically shown in the label, or caption of an UI Element that is bound to an attribute of this type.
For a data element, we can create documentation F1 Help with Goto -> Documentation -> Change. This documentation is not seen on screen if the Web Dynpro application attribute WDHIDEMOREFIELDHELPASDEFAULT was set as ABAP_TRUE. We create a text that describes the content of our data element.
Creating a F1 help for a data element
A domain defines a value range.To be able to use it in a Web Dynpro application,in other repository object, as parameter in GUI programming,etc.we have to assign it to a data element
Data elements and domains
We create a domain named Y_COUNTRY_DOMAIN that holds all the names of EU member states, with the proper abbreviation. In “Definition” tab we have to specify properties as data type, number of characters or length of output
Definition of a domain – tab “Definition”
In “Value Range” we have three possibilities:
- Single values
- Intervals
- Value table
We begin with the first possibility, “Single values”. We define the domain fixed values – all the abbreviations of the EU countries, and a short text – the corresponding country names.
Definition of a domain – tab “Value Range”
As we have specified, to be able to use a domain we have to assign it to a data element. To do this, we create a new data element and we choose the elementary type – domain.
Assigning a domain to a data element
When we use this data element in our Web Dynpro application, for example to define a parameter or a context attribute, the user is allowed to choose only the values that range among values we have defined in Domain.
To explain the next possibility (“Intervals”), we take an example where we need to store, in a table column, the ages between 18 and 45. In this case, we can use an interval to limit the values that the user may enter.
Definition of a domain – interval
We use this interval in the database table YPERSON, defined hereinafter. For this, we assign it to a data element Y_DEINTERVAL.
To explain the last possibility (“Value Table”), we use a domain that is defined in the system: WAERS.
Domain WAERS – value table
It is recommendable to use the value table when we have many fixed values. In our case, we have used the system table TCURC. This table holds all the system currency.
We use this value table in the database table YEU_COUNTRIES, defined hereunder. For this, we assign it to a data element Y_CURRENCY.
Structures consist of any combination of other data types of the ABAP Dictionary.In fig. we present a structure with three components: FIRSTNAME, LASTNAME and DATEOFBIRTH.
Definition of a structure
For each component it is defined a component type, as follows: a data element,other structure, table type, etc.
As a component type for a structure, we can choose a type that is already defined in the ABAP Dictionary, or we can create a new type. For example, the component DATEOFBIRTH has YDATEOFBIRTH data type. This data type has been already defined.
If we want to create a new type for a component, we have to enter its name (for example, YFIRSTNAME) and then, with double-click, we can choose the new type.
Creating a new component type
After we create a structure, we have to maintain the enhancement category: Extras ! Enhancement Category, from the menu. In case we don’t want to further extend the component structure, we choose “Cannot be Enhanced”.
Maintaining enhancement category
We can use the structures defined in ABAP Dictionary to create the context node structure for a Web Dynpro application.
We create two transparent tables, YPERSON and YEU_COUNTRIES. We will use this table later, for our Web Dynpro example.
In the YPERSON table, we want to store the competition candidates. All the candidates should be 18–45 years old and live in an EU country. After creating the table, we have to enter a short description along with the delivery and maintenance
Table maintenance
We set “Data Browser/Table View Main” ! Display/Maintenance Allowed, to be able to populate our table with values, using “Create Entries”, from the menu.
Then, we will define our table structure. To do this, we select the tab “Fields” and enter the table columns For the fields MANDT and ID_PERSON, we have marked the option “Key”, meaning they are the table keys. The field MANDT is the SAP client field, a three-character client ID. The field “ID_PERSON” represents the candidate’s ID, required to uniquely identify each competition candidate.
Table structure
As can be seen, we have used the data elements created hereinbefore: YFIRSTNAME, YLASTNAME, Y_DEINTERVAL, Y_DEFORDOMAIN. When we want to create a new data element, we write its name and, with double-click, we activate the forward navigation. If this data element doesn’t exist, we are asked if we want to create the new data element.
Creating a data element
Before being able to activate this table, we have to maintain the technical settings
How to maintain the technical settings for the table YPERSON
We choose a size category 0, because we don’t require many data records. We have to maintain the enhancement category: Extras -> Enhancement Category, from the Menu. We choose the same “Cannot be Enhanced”, because we shouldn’t further extend the table structure. After this, we can activate our table and create the second table YEU_COUNTRIES.
We hold here all the EU Member states information, as follows: country name, year of EU entry, political system, capital city, currency and the flag image name. The structure of this table is presented.
Table structure
After this, we have to define a foreign key for the field CHECK_CUR. For this purpose, we use the button “Foreign Keys”. We are asked if we want to use the value table TCURC as check table.
How to create foreign key
We need TCUC as a check table, because we want to use its table contents, respectively the Currency Codes.
Currency codes
After we maintain the Technical settings and enhancement category, we can activate the same as for the table YPERSON.
The candidates can live only in an EU country. Therefore, we create a 1 to CN relationship between the tables.
From the table YPERSON field ID_COUNTRY, we create a foreign key.
How to create a foreign key
The system can generate the graphical representation of the relationships we have defined between tables. To show this graph,we use the Button “Graph”.
Foreign key relation ship
We can see our tables YEU_COUNTRIES, YPERSON and the 1:CN relationship.
The table TCUC is the check table for the table YEU_COUNTRIES. To see this relationship also, we have to select the name of YEU_COUNTRIES table and to press the Button “Check Table”.
Foreign key relation ship
We can create contents withUtilities --> Table content --> Create Entries from Menu
Insert – table YEU_COUNTRIES
To display the content: Utilities --> Table content --> Display from Menu.
Select – table YEU_COUNTRIES
We can use the transparent tables defined in the ABAP Dictionary to create the context node structure for a Web Dynpro application.
ABAP Dictionary offers the possibility to create simple search help and collective search help. To create a search help, we can use the context menu of our package.
Creating a development object in the ABAP Dictionary by using the Object Navigator
We create a simple search help YSH_ID_PERSON for the column ID_PERSON of the table YPERSON
Creating a simple search help
As can be seen at Data collection ! Selection method, we have used the table name YPERSON. This means that all the data required come from our table YPERSON. A search help can have the following parameters: “import parameters”, “export parameters” or “no import” and “no export”. We have used ID_PERSON as export parameter, because we want its value to be returned to the input template. LPos represents the parameter position in the hit list: FIRSTNAME has the position 1 and it is firstly displayed in the hit list, and LASTNAME has the position 2, being displayed after the FIRSTNAME.
Testing a search help
Afterwards, we want to use this search help in a Web Dynpro application. We create a search option for a competitor. The user has to enter the competitor’s ID into a search mask. The list of IDs is limited to the number of competitors. When the user doesn’t know the competitor’s ID, he uses the search help and can choose the competitor’s name. The content of the ID_PERSON parameter is returned to the search mask as soon as the user has selected a line of the hit list in the input help. In this way, we facilitate the input.
We can use this search help if we link it with the ID_PERSON column of the YPERSON table. To do this, we select the column ID_PERSON and press the button “Srch Help”.
Search Help for the field ID_PERSON
After we enter the search help name, we have to create the search help attachment, and to save and activate the table
How to create search help attachment to the column ID_PERSON
In this way, we have created a simple search help for the column ID_PERSON of the table YPERSON. When we use this column in Web Dynpro, the Framework creates a special icon to be used at the runtime to call the input help. Moreover, we can use the keyboard key F4 to call an input help.
To be able to access a search help from a WD component, the proper Input Help Mode context attribute property has to be set (“Automatic” or “Dictionary Search Help”).
By using a view, we can combine the data distributed in several tables. For a better understanding, we create a view on the tables YPERSON and YEU_COUNTRIES. When we create a view, we can choose one of the four view types.
View types
We choose to create a database view named YVIEW_CMPETITION. At the beginning of the “view definition”, we have to select the view base table (in ourcase, the table YPERSON.After the base table definition, we link this table by defining the joining conditions. To create this link, we use the button “Relationships”.
Creating a view
Joining conditions
In the next step, we have to select the fields we need in our view. We can enter each field manually or we can use the Button “Table fields”.
View fields
After activation, we can see our view content using the “Contents Button”.
View content
In this way, we have created a database view on the tables YPERSON and YEU_COMPETITION.
View definition on the database
By using this view, we can create the context node structure for our Web Dynpro application and so we simultaneously select the logically connected data, from two tables.
We create a table type named YTABLE_TYPE, the line type being our YPERSON table
Creating a table type
For the line type, we can use an existing type (table, structure, view, . . .) or we can enter the data type, length and number of decimals. The typical use of table type is the declaration of an internal table.
Another example of using table type is to populate with values a context node via a supply function. To be able to do this, we create a table type named YTABLE_ TYPE_STRUCTURE with the line type – the structure YSTR_PERSON.
Table type – line type structure
In the next chapter, we show how we can use this table type to populate a context node.
We create a Lock Object for the database table YPERSON. The lock object name has to begin with the prefix E (from “Enqueue”).
Lock object
Our case consists of exactly one table, and the lock argument is the primary key of this table. The lock mode is set to write, but can be overwritten.
After the lock object activation, the ABAP Dictionary generates two Function Modules, named ENQUEUE_ and DEQUEUE_. The Function Modules with enqueue prefix help us to set a lock, and the Function Modules with dequeue prefix help us to release the locks.
With the SE37 transaction we can see the two generated Function Modules: ENQUEUE_EYPERSON and DEQUEUE_EYPERSON. Figure shows the structure of the Function Module required to set a lock.
Function Module for lock setting
SAP offers a lock mechanism required to provide two transactions by simultaneously changing the same data in the database. The lock table represents a table in the memory of the enqueue server and is used to manage all the locks in the system. This lock table is checked every time when the enqueue server receives a lock request. A program sends, to the lock table, the key of the table entries it wants to lock; if no lock is set, the request is accepted and the new lock is written in the lock table. If a lock is set, the request collides with an existing lock and the request is rejected.
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