ABAP Objects v/s Field Symbols
Hi,
My query is:
In ABAP Objects, reference variables can be assigned to each other.
We can also assign the reference variable to a field symbol.
Does that mean, that we can achieve the same functionality(like accessing a method of the class) using the field-symbols?
If so, why not use field-symbols instead of objects? What are the other differences?
Please provide your opinions.
Regards
s.a.k
Hi,
We can have any number of Field Symbols refering to One Variable or Object, but all these Field symbols refer to same memory location they donto have individual memory locations.
Where are in Object, if diffrent objected are created refreing to one object all the objects have diffrent memory locations.
Read the documentation of Field symbols and ABAP Objects you will get the clear diffrene.
Regards,
Kumar M.
Similar Messages
-
Hi all,
Can anyone explains what is Fiels symbol and significance of that with examples?
Thanks
ShivaHI Shiva
Field symbols are placeholders or symbolic names for other fields. They do not physically reserve space for a field, but point to its contents. A field symbol cam point to any data object. The data object to which a field symbol points is assigned to it after it has been declared in the program.
Whenever you address a field symbol in a program, you are addressing the field that is assigned to the field symbol. After successful assignment, there is no difference in ABAP whether you reference the field symbol or the field itself. You must assign a field to each field symbol before you can address the latter in programs.
Field symbols are similar to dereferenced pointers in C (that is, pointers to which the content operator * is applied). However, the only real equivalent of pointers in ABAP, that is, variables that contain a memory address (reference) and that can be used without the contents operator, are reference variables in ABAP Objects. (For more information, see Data References).
All operations programmed with field symbols are applied to the field assigned to it. For example, a MOVE statement between two field symbols moves the contents of the field assigned to the first field symbol to the field assigned to the second field symbol. The field symbols themselves point to the same fields after the MOVE statement as they did before.
You can create field symbols either without or with type specifications. If you do not specify a type, the field symbol inherits all of the technical attributes of the field assigned to it. If you do specify a type, the system checks the compatibility of the field symbol and the field you are assigning to it during the ASSIGN statement.
Field symbols provide greater flexibility when you address data objects:
If you want to process sections of fields, you can specify the offset and length of the field dynamically.
You can assign one field symbol to another, which allows you to address parts of fields.
Assignments to field symbols may extend beyond field boundaries. This allows you to address regular sequences of fields in memory efficiently.
You can also force a field symbol to take different technical attributes from those of the field assigned to it.
The flexibility of field symbols provides elegant solutions to certain problems. On the other hand, it does mean that errors can easily occur. Since fields are not assigned to field symbols until runtime, the effectiveness of syntax and security checks is very limited for operations involving field symbols. This can lead to runtime errors or incorrect data assignments.
While runtime errors indicate an obvious problem, incorrect data assignments are dangerous because they can be very difficult to detect. For this reason, you should only use field symbols if you cannot achieve the same result using other ABAP statements.
For example, you may want to process part of a string where the offset and length depend on the contents of the field. You could use field symbols in this case. However, since the MOVE statement also supports variable offset and length specifications, you should use it instead. The MOVE statement (with your own auxiliary variables if required) is much safer than using field symbols, since it cannot address memory beyond the boundary of a field. However, field symbols may improve
To declare a field symbol, use the statement
FIELD-SYMBOLS <FS> [<type>|STRUCTURE <s> DEFAULT <wa>].
For field symbols, the angle brackets are part of the syntax. They identify field symbols in the program code.
If you do not specify any additions, the field symbol <FS> can have data objects of any type assigned to it. When you assign a data object, the field symbol inherits its technical attributes. The data type of the assigned data object becomes the actual data type of the field symbol.
Note: it is possible to assign reference variables and structured data objects to untyped field symbols. However, the static field symbol is only a pointer to the field in memory, and does not have the complex type attributes of a reference or structured field until runtime. You can only use the field symbol to address the whole field (for example, in a MOVE statement). Specific statements such as CREATE OBJECT <FS> or LOOP AT <FS> are not possible.
Typing Field Symbols
The <type> addition allows you to specify the type of a field symbol. When you assign a data object to a field symbol, the system checks whether the type of the data object you are trying to assign is compatible with that of the field symbol. If the types are not compatible or convertible, the system reacts with a syntax or runtime error. If however, you want to assign the type of the field symbol to the data object by means of casting, you must do so explicitly using the ASSIGN statement. The system then treats the assigned data object as if it had the same type as the field symbol.
You specify the type of a field symbol using the same semantics as for formal parameters in procedures. For <type> you can enter either TYPE <t> or LIKE <f>. You can specify the type either generically or in full. If you specify a generic type, the type of the field symbol is either partially specified or not specified at all. Any attributes that are not specified are inherited from the corresponding data object in the ASSIGN statement. If you specify the type fully, all of the technical attributes of the field symbol are determined when you define it. You can then only assign data objects to it that have exactly the same data type.
You should always specify a type for each field symbol. If you cannot avoid defining a generic field symbol, make this clear by using an appropriate generic type declaration.
Generic Type Specification
The following types allow you more freedom when using actual parameters. The data object only needs to have the selection of attributes specified.
Typing
Check for data object
No type specification
TYPE ANY
All types of data object are accepted. The field symbol adopts all of the attributes of the data object.
TYPE C, N, P, or X
Only data objects with type C, N, P, or X are accepted. The field symbol adopts the field length and DECIMALS specification (type P) of the data object.
TYPE TABLE
The system checks whether the data object is a standard internal table. This is a shortened form of TYPE STANDARD TABLE (see below).
TYPE ANY TABLE
The system checks whether the data object is an internal table. The field symbol inherits all of the attributes (line type, table type, key) from the data object.
TYPE INDEX TABLE
The system checks whether the data object is an index table (standard or sorted table). The field symbol inherits all of the attributes (line type, table type, key) from the data object.
TYPE STANDARD TABLE
The system checks whether the data object is a standard internal table. The field symbol inherits all of the remaining attributes (line type, key) from the data object.
TYPE SORTED TABLE
The system checks whether the actual parameter is a sorted internal table. The field symbol inherits all of the remaining attributes (line type, key) from the data object.
TYPE HASHED TABLE
The system checks whether the actual parameter is a hashed internal table. The field symbol inherits all of the remaining attributes (line type, key) from the data object.
If you specify a type generically, remember that the attributes inherited by the field symbol from the program are not statically recognizable in the program. You can, at most, address them dynamically.
TYPES: BEGIN OF line,
col1 TYPE c,
col2 TYPE c,
END OF line.
DATA: wa TYPE line,
itab TYPE HASHED TABLE OF line WITH UNIQUE KEY col1,
key(4) TYPE c VALUE 'COL1'.
FIELD-SYMBOLS <fs> TYPE ANY TABLE.
ASSIGN itab TO <fs>.
READ TABLE <fs> WITH TABLE KEY (key) = 'X' INTO wa.
The internal table ITAB is assigned to the generic field symbol <FS>, after which it is possible to address the table key of the field symbol dynamically. However, the static address
READ TABLE <fs> WITH TABLE KEY col1 = 'X' INTO wa.
is not possible syntactically, since the field symbol does not adopt the key of table ITAB until runtime. In the program, the type specification ANY TABLE only indicates that <FS> is a table. If the type had been ANY (or no type had been specified at all), even the specific internal table statement READ TABLE <FS> would not have been possible.
If you adopt a structured type generically (a structure, or a table with structured line type), the individual components cannot be addressed in the program either statically or dynamically. In this case, you would have to work with further field symbols and the method of assigning structures component by component.
Specifying the Type Fully
When you use the following types, the technical attributes of the field symbols are fully specified. The technical attributes of the data objects must correspond to those of the field symbol.
Typing
Technical attributes of the field symbol
TYPE D, F, I, or T
The field symbol has the technical attributes of the predefined elementary type
TYPE <type>
The field symbol has the type <type>. This is a data type defined within the program using the TYPES statement, or a type from the ABAP Dictionary
TYPE REF TO <cif>|DATA
The field symbol is a reference variable for the class or interface <cif>, or for a data object.
TYPE LINE OF <itab>
The field symbol has the same type as a line of the internal table <itab> defined using a TYPES statement or defined in the ABAP Dictionary
LIKE <f>
The field symbol has the same type as an internal data object <f> or structure, or a database table from the ABAP Dictionary
When you use a field symbol that is fully typed, you can address its attributes statically in the program, since they are recognized in the source code. If you fully specify the type of a field symbol as a reference or structured data object, you can address it as you would the data object itself, once you have assigned an object to it. So, for example, you could address the components of a structure, loop through an internal table, or create an object with reference to a field symbol.
REPORT demo_field_symbols_type .
DATA: BEGIN OF line,
col1(1) TYPE c,
col2(1) TYPE c VALUE 'X',
END OF line.
FIELD-SYMBOLS <fs> LIKE line.
ASSIGN line TO <fs>.
MOVE <fs>-col2 TO <fs>-col1.
The field symbol <FS> is fully typed as a structure, and you can address its components in the program.
Attaching a structure to a field symbol
The STRUCTURE addition forces a structured view of the data objects that you assign to a field symbol.
FIELD-SYMBOLS <FS> STRUCTURE <s> DEFAULT <f>.
The structure <s> is either a structured local data object in the program, or a flat structure from the ABAP Dictionary. <f> is a data object that must be assigned to the field symbol as a starting field. However, this assignment can be changed later using the ASSIGN statement.
When you assign a data object to the field symbol, the system only checks that it is at least as long as the structure. You can address the individual components of the field symbol. It has the same technical attributes as the structure <s>.
If <s> contains components with type I or F, you should remember the possible effects of alignment. When you assign a data object to a field symbol with a structure, the data object must have the same alignment, otherwise a runtime error may result. In such cases, you are advised to assign such data objects only to structured field symbols, which retain the same structure as the field symbol at least over the length of the structure.
The STRUCTURE is obsolete; you should no longer use it. Field symbols defined using the STRUCTURE addition are a mixture of typed field symbols and a utility for casting to either local or ABAP Dictionary data types. If you want to define the type of a field symbol, include the TYPE addition in a FIELD-SYMBOLS statement. If you want to use casting, include the CASTING addition in an ASSIGN statement.
Example using the obsolete STRUCTURE addition:
DATA: wa(10) VALUE '0123456789'.
DATA: BEGIN OF line1,
col1(3),
col2(2),
col3(5),
END OF line1.
DATA: BEGIN OF line2,
col1(2),
col2 LIKE sy-datum,
END OF line2.
FIELD-SYMBOLS: <f1> STRUCTURE line1 DEFAULT wa,
<f2> STRUCTURE line2 DEFAULT wa.
WRITE: / <f1>-col1, <f1>-col2, <f1>-col3,
/ <f2>-col1, <f2>-col2.
Example using the correct syntax (TYPE and CASTING):
DATA: wa(10) VALUE '0123456789'.
DATA: BEGIN OF line1,
col1(3),
col2(2),
col3(5),
END OF line1.
DATA: BEGIN OF line2,
COL1(2),
COL2 LIKE sy-datum,
END OF line2.
FIELD-SYMBOLS: <f1> LIKE line1.
ASSIGN wa TO <f1> CASTING.
FIELD-SYMBOLS: <f2> LIKE line2.
ASSIGN wa TO <f2> CASTING.
WRITE: / <f1>-col1, <F1>-col2, <F1>-col3,
/ <f2>-col1, <F2>-col2.
In both cases, the list appears as follows:
012 34 56789
01 2345/67/89
This example declares two field symbols to which different structures are attached. The string WA is then assigned to each of them. The output shows that the field symbols assign the strings component by component according to the type of the components.
Assigning Components of Structures to a Field Symbol
For a structured data object <s>, you can use the statement
ASSIGN COMPONENT <comp> OF STRUCTURE <s> TO <FS>.
to assign one of its components <comp> to the field symbol <FS>. You can specify the component <comp> either as a literal or a variable. If <comp> is of type C or a structure that has no internal tables as components, it specifies the name of the component. If <comp> has any other elementary data type, it is converted to type I and specifies the number of the component. If the assignment is successful, SY-SUBRC is set to 0. Otherwise, it is set to 4.
This statement is particularly important for addressing components of structured data objects dynamically. If you assign a data object to a field symbol either generically or using casting, or pass it generically (or using casting) to the parameter interface of a procedure, you cannot address its components either statically or dynamically. Instead, you must use the above statement. This allows indirect access either using the component name or its index number.
DATA: BEGIN OF LINE,
COL1 TYPE I VALUE '11',
COL2 TYPE I VALUE '22',
COL3 TYPE I VALUE '33',
END OF LINE.
DATA COMP(5) VALUE 'COL3'.
FIELD-SYMBOLS: <F1>, <F2>, <F3>.
ASSIGN LINE TO <F1>.
ASSIGN COMP TO <F2>.
DO 3 TIMES.
ASSIGN COMPONENT SY-INDEX OF STRUCTURE <F1> TO <F3>.
WRITE <F3>.
ENDDO.
ASSIGN COMPONENT <F2> OF STRUCTURE <F1> TO <F3>.
WRITE / <F3>.
The output is:
11 22 33
33
The field symbol <F1> points to the structure LINE, <F2> points to the field COMP. In the DO loop, the components of LINE are specified by their numbers and assigned one by one to <F3>. After the loop, the component COL3 of LINE is specified by its name and assigned to <F3>. Note that ASSIGN COMPONENT is the only possible method of addressing the components of <F1>. Expressions such as <F1>-COL1 are syntactically incorrect.
Regards,
Laxmi. -
Hello :i would like to ask one favor , how can i define a field symbol, that can recieve a dynamic variable
segment of code:
CALL METHOD cl_alv_table_create=>create_dynamic_table
EXPORTING
it_fieldcatalog = it_fldcat
IMPORTING
ep_table = it_dynamic.
ASSIGN it_dynamic->* TO <dyn_table>.
CREATE DATA wa_dynamic LIKE line of <dyn_table>.
ASSIGN wa_dynamic->* TO <dyn_wa>. " this one 'wa_dynamic' i need to sent to <dyn_wa>
thanks a lotHI
GOOD
Generic Type Specification
The following types allow you more freedom when using actual parameters. The data object only needs to have the selection of attributes specified.
Typing
Check for data object
No type specification
TYPE ANY
All types of data object are accepted. The field symbol adopts all of the attributes of the data object.
TYPE C, N, P, or X
Only data objects with type C, N, P, or X are accepted. The field symbol adopts the field length and DECIMALS specification (type P) of the data object.
TYPE TABLE
The system checks whether the data object is a standard internal table. This is a shortened form of TYPE STANDARD TABLE (see below).
TYPE ANY TABLE
The system checks whether the data object is an internal table. The field symbol inherits all of the attributes (line type, table type, key) from the data object.
TYPE INDEX TABLE
The system checks whether the data object is an index table (standard or sorted table). The field symbol inherits all of the attributes (line type, table type, key) from the data object.
TYPE STANDARD TABLE
The system checks whether the data object is a standard internal table. The field symbol inherits all of the remaining attributes (line type, key) from the data object.
TYPE SORTED TABLE
The system checks whether the actual parameter is a sorted internal table. The field symbol inherits all of the remaining attributes (line type, key) from the data object.
TYPE HASHED TABLE
The system checks whether the actual parameter is a hashed internal table. The field symbol inherits all of the remaining attributes (line type, key) from the data object.
If you specify a type generically, remember that the attributes inherited by the field symbol from the program are not statically recognizable in the program. You can, at most, address them dynamically.
TYPES: BEGIN OF line,
col1 TYPE c,
col2 TYPE c,
END OF line.
DATA: wa TYPE line,
itab TYPE HASHED TABLE OF line WITH UNIQUE KEY col1,
key(4) TYPE c VALUE 'COL1'.
FIELD-SYMBOLS <fs> TYPE ANY TABLE.
ASSIGN itab TO <fs>.
READ TABLE <fs> WITH TABLE KEY (key) = 'X' INTO wa.
The internal table ITAB is assigned to the generic field symbol <FS>, after which it is possible to address the table key of the field symbol dynamically. However, the static address
READ TABLE <fs> WITH TABLE KEY col1 = 'X' INTO wa.
is not possible syntactically, since the field symbol does not adopt the key of table ITAB until runtime. In the program, the type specification ANY TABLE only indicates that <FS> is a table. If the type had been ANY (or no type had been specified at all), even the specific internal table statement READ TABLE <FS> would not have been possible.
If you adopt a structured type generically (a structure, or a table with structured line type), the individual components cannot be addressed in the program either statically or dynamically. In this case, you would have to work with further field symbols and the method of assigning structures component by component.
Specifying the Type Fully
When you use the following types, the technical attributes of the field symbols are fully specified. The technical attributes of the data objects must correspond to those of the field symbol.
Typing
Technical attributes of the field symbol
TYPE D, F, I, or T
The field symbol has the technical attributes of the predefined elementary type
TYPE <type>
The field symbol has the type <type>. This is a data type defined within the program using the TYPES statement, or a type from the ABAP Dictionary
TYPE REF TO <cif>|DATA
The field symbol is a reference variable for the class or interface <cif>, or for a data object.
TYPE LINE OF <itab>
The field symbol has the same type as a line of the internal table <itab> defined using a TYPES statement or defined in the ABAP Dictionary
LIKE <f>
The field symbol has the same type as an internal data object <f> or structure, or a database table from the ABAP Dictionary
When you use a field symbol that is fully typed, you can address its attributes statically in the program, since they are recognized in the source code. If you fully specify the type of a field symbol as a reference or structured data object, you can address it as you would the data object itself, once you have assigned an object to it. So, for example, you could address the components of a structure, loop through an internal table, or create an object with reference to a field symbol.
REPORT demo_field_symbols_type .
DATA: BEGIN OF line,
col1(1) TYPE c,
col2(1) TYPE c VALUE 'X',
END OF line.
FIELD-SYMBOLS <fs> LIKE line.
ASSIGN line TO <fs>.
MOVE <fs>-col2 TO <fs>-col1.
The field symbol <FS> is fully typed as a structure, and you can address its components in the program.
Attaching a structure to a field symbol
The STRUCTURE addition forces a structured view of the data objects that you assign to a field symbol.
FIELD-SYMBOLS <FS> STRUCTURE <s> DEFAULT <f>.
The structure <s> is either a structured local data object in the program, or a flat structure from the ABAP Dictionary. <f> is a data object that must be assigned to the field symbol as a starting field. However, this assignment can be changed later using the ASSIGN statement.
When you assign a data object to the field symbol, the system only checks that it is at least as long as the structure. You can address the individual components of the field symbol. It has the same technical attributes as the structure <s>.
If <s> contains components with type I or F, you should remember the possible effects of alignment. When you assign a data object to a field symbol with a structure, the data object must have the same alignment, otherwise a runtime error may result. In such cases, you are advised to assign such data objects only to structured field symbols, which retain the same structure as the field symbol at least over the length of the structure.
The STRUCTURE is obsolete; you should no longer use it. Field symbols defined using the STRUCTURE addition are a mixture of typed field symbols and a utility for casting to either local or ABAP Dictionary data types. If you want to define the type of a field symbol, include the TYPE addition in a FIELD-SYMBOLS statement. If you want to use casting, include the CASTING addition in an ASSIGN statement.
Example using the obsolete STRUCTURE addition:
DATA: wa(10) VALUE '0123456789'.
DATA: BEGIN OF line1,
col1(3),
col2(2),
col3(5),
END OF line1.
DATA: BEGIN OF line2,
col1(2),
col2 LIKE sy-datum,
END OF line2.
FIELD-SYMBOLS: <f1> STRUCTURE line1 DEFAULT wa,
<f2> STRUCTURE line2 DEFAULT wa.
WRITE: / <f1>-col1, <f1>-col2, <f1>-col3,
/ <f2>-col1, <f2>-col2.
Example using the correct syntax (TYPE and CASTING):
DATA: wa(10) VALUE '0123456789'.
DATA: BEGIN OF line1,
col1(3),
col2(2),
col3(5),
END OF line1.
DATA: BEGIN OF line2,
COL1(2),
COL2 LIKE sy-datum,
END OF line2.
FIELD-SYMBOLS: <f1> LIKE line1.
ASSIGN wa TO <f1> CASTING.
FIELD-SYMBOLS: <f2> LIKE line2.
ASSIGN wa TO <f2> CASTING.
WRITE: / <f1>-col1, <F1>-col2, <F1>-col3,
/ <f2>-col1, <F2>-col2.
In both cases, the list appears as follows:
012 34 56789
01 2345/67/89
This example declares two field symbols to which different structures are attached. The string WA is then assigned to each of them. The output shows that the field symbols assign the strings component by component according to the type of the components.
http://help.sap.com/saphelp_nw04/helpdata/en/fc/eb387a358411d1829f0000e829fbfe/content.htm
THANKS
MRUTYUN -
Hi
How can i use the fields-symbols in Abap Object (class)?: The program <b>SAPLMIGO</b> have a table <b>oref_detail->t_goserial</b>. I would get this table in my program (not object) by using field-symbol
What can i do?
it's urgent
thanks a lotHello
Here are the fact:
(1) oref_detail is of TYPE REF TO lcl_migo_detail (local class)
* Detail
oref_detail TYPE REF TO lcl_migo_detail, (lines 244-245 in LMIGOTOP)
(2) Here is the definition of the local class (LMIGODC1):
* INCLUDE LMIGODC1 *
* Detail carrier (data manager)
CLASS lcl_migo_detail DEFINITION
INHERITING FROM lcl_migo_screenobject.
PUBLIC SECTION.
INTERFACES:
lif_migo_frame.
DATA:
* Line in the model which is currently displayed
current_line TYPE sytabix READ-ONLY,
* table for working with serial numbers internally
t_goserial TYPE lcl_migo_kernel=>ty_t_goserial,
" need to be changed when friend
" concept is available
* table for working with freight vendors internally
t_gofreight TYPE TABLE OF gofreight." need to be changed when friend
" concept is availible
METHODS:
constructor,
pbo REDEFINITION,
pbo_godynpro_fill,
pai REDEFINITION,
pai_get,
pai_transfer_fields_fill,
line_find. "ON REQUEST
PRIVATE SECTION.
DATA:
p_global_counter TYPE goitem-global_counter, "old gobal_counter
"(before sort/Not OK)
p_last_new_line_mode TYPE char1,
poref_settings TYPE REF TO cl_mmim_userdefaults,
ps_old_goitem TYPE goitem. "goitem before PAI-field transport
METHODS:
transfer_item_copy.
ENDCLASS. "lcl_migo_detail DEFINITIO
(3) t_goserial has the following definition (include LMIGOKE1):
* Serial number with SELECTED-flag
BEGIN OF ty_s_goserial,
selected TYPE xfeld,
serialno TYPE gernr,
END OF ty_s_goserial,
ty_t_goserial TYPE STANDARD TABLE OF ty_s_goserial WITH
NON-UNIQUE DEFAULT KEY,
What does it mean that you want to "access" this internal table? Do you need this itab within a userexit or BAdI?
Regards
Uwe -
Hi
How can i use the fields-symbols in Abap Object (class)?: The program <b>SAPLMIGO</b> have a table <b>oref_detail->t_goserial</b>. I would get this table in my program (not object) by using field-symbol
What can i do?
it's urgent
thanks a lotHi,
You can try this
field-symbols: <tab> type table.
create object o ...
assign o->t_values to <tab>.
You need to create the object. -
Reg: Field Symbol and Data Reference
Hi,
What is the difference Between a FieldSymbol and Data Reference.
could anyone explain with an example the difference.
The Link I am Going Through ---> [SAP HELP|http://help.sap.com/saphelp_nw04/helpdata/en/fc/eb3860358411d1829f0000e829fbfe/frameset.htm]
I couldnt get a clear idea
regardsHi,
In ABAP/4 programs, field symbols are placeholders for existing fields. A field symbol does not physically reserve space for a field, but points to a field, which is not known until runtime of the program. Field symbols are comparable to the concept of pointers as used in the programming language C. In ABAP/4, however, there is no real equivalent to pointers in the sense of variables, which contain a memory address and can be used without the content operator. You can only work with the data object to which a field symbol points.
uF076 Concept of Field Symbols
Sometimes you only know which field you want to process, and how you want to process it, at runtime.
For this purpose, you can create field symbols in your program. At runtime, you can assign real fields to such field symbols. All operations, which you have programmed with the field symbol, are then carried out with the assigned field. After successful assignment, there is no difference in ABAP/4 whether you reference the field symbol or the field itself.
Field symbols can point to any data object in ABAP/4 and to structures defined in the ABAP/4 Dictionary.
You can create field symbols either without or with type specifications. In the first case, the field symbol adopts all the attributes of the assigned field. In the second case, the system checks during the assignment process whether the assigned field matches the type of the field symbol. Whichever applies, you must first assign a field to your field symbol before you can work with it in your program.
Field symbols provide some features that make them very flexible:
uF071 You can specify the offset and length of the assigned field as variables.
uF071 You can assign field symbols to other field symbols and even specify offset and length there.
uF071 Assignments to field symbols may extend beyond field boundaries. This allows effective access to regularly stored data.
uF071 You can force a field symbol to be of a different type and to have a different number of decimal places than the assigned field.
uF071 Field symbols may have a structure that you can use to point to individual components of structures.
Since you can assign data objects to field symbols which may not be known until runtime, the effectiveness of syntax and security checks is very limited for operations involving field symbols. This can lead to runtime errors or incorrect data assignments.
While runtime errors indicate an obvious problem, incorrect data assignments are dangerous because they can be very difficult to detect. Therefore, you should use field symbols only in cases where you are absolutely sure of what you are doing, or if there are no other ABAP/4 statements you can use to solve your problem. The advantage of field symbols is that they can improve response times in some cases.
uF076 Defining Field Symbols
uF0D8 Defining Field Symbols for Internal Fields
To define a field symbol for an internal data object, use the FIELD-SYMBOLS statement as follows:
Syntax-
FIELD-SYMBOLS <FS> [<type>].
This statement defines a field symbol <FS>.
for data reference follow this link
http://help.sap.com/saphelp_nw04s/helpdata/en/14/11e70b0c5c11d3b9350000e8353423/frameset.htm
Regards,
Flavya -
Hi,
I am confused with append statement when using field symbols.
When I use append <WA1> to t_FINAL. it throws an error saying T_FINAL is not an internal table "OCCURS N" is missing..
I cannot use occurs statement because I am doing OO ABAP.ANy ideas?
FIELD-SYMBOLS <wa> LIKE LINE OF bookmk.
FIELD-SYMBOLS <wa1> LIKE LINE OF bookmk.
LOOP AT T_ITAB ASSIGNING <wa>.
SEARCH <wa>-url FOR '&XYZZZ'.
IF sy-subrc IS INITIAL.
ASSIGN t_FINAL TO <wa1>.
MOVE-CORRESPONDING <wa> TO <wa1>.
****???????append <WA1> to t_FINAL.
ENDIF.
ENDLOOP.Hi there..
FIELD-SYMBOLS <wa> LIKE LINE OF bookmk.
FIELD-SYMBOLS <wa1> LIKE LINE OF bookmk.
datA: it_final type standard table of bookmk."<<<use this table decl -
How to use field-symbols in MODIFY ... TRANSPORTING and SORT
Hi,
I need to increase the performance of an abap report using the field-symbols. More exactly the code is the following.
TYPES:
BEGIN OF itab_structure.
INCLUDE STRUCTURE nameofstructure.
TYPES:
RECNO LIKE sy-tabix,
END OF itab_structure.
DATA:
itab TYPE STANDARD TABLE OF itab_structure
WITH HEADER LINE
WITH NON-UNIQUE DEFAULT KEY INITIAL SIZE 0.
SORT itab ASCENDING BY f1.
LOOP AT itab WHERE f1 = '10'.
itab-fn= value-n.
MODIFY itab
TRANSPORTING fx fy fz ft
WHERE f1 = c1_filed AND
f2 = c2_field.
ENDLOOP.
I need your suggestions in this kind of conversion or solution.
SORT itab ASCENDING BY f1 (<-- I don't know if in this case the better performances should be obtained using field symbols and in which way)
FIELD-SYMBOLS: <fs_itab_line> TYPE LINE OF itab.
LOOP AT itab ASSIGNING <fs_itab_line> WHERE
<fs_itab_line>-f1 = '10'.
MODIFY itab
TRANSPORTING fx fy fz ft
WHERE f1 = c1_filed AND
f2 = c2_field.
(I don't know if in this case the better performances should be obtained using field symbols and in which way)
ENDLOOP.
I wish to implement the field symbols or the better performance in terms of execution time in all my abap code, where it is possible.
Any suggestion will be well appreciated.
Thanks in advance for your kind support.
Regards,
GiovanniDear All,
I have appeciated your suggestions and I can conclude these points in my case:
1) The "sort" statement is not optimized in a different way using filed-symbols
2) The loop with "where" condition on a standard table is performed using filed-symbols
But ... my last point to investigate is about the statement MODIFY table TRANSPORTING f1, f2 WHERE conditions.
More exactly, in my code the execution logic of the abap code expects a global modification of the same table at the end of every (primary) loop, using the MODYFY statement.
In other words in my code I can locate two loops on the same table in the following logic:
LOOP AT table1 WHERE f1 = '10'. (#1)
updates to table1
set c1_filed, c2_filed
LOOP AT table1. (#2)
IF f1 = c1_filed AND
f2 = c2_filed.
table1-fx = 'x'.
table1-fy = 'y'.
table1-fz = 'z'.
table1-ft = 't'.
ENDIF.
MODIFY table1.
ENDLOOP. (#2)
ENDLOOP. (#1)
In better way (maybe more fast in terms of execution time) to modify a set of lines (MODIFY...TRANSPORTING...WHERE):
LOOP AT table1 WHERE f1 = '10'.
table1-fx= 'x'.
table1-fy= 'y'.
table1-fz= 'z'.
table1-ft= 't'.
MODIFY itab
TRANSPORTING fx fy fz ft
WHERE f1 = c1_filed AND
f2 = c2_field.
ENDLOOP.
My aim is to use field-symbols everywhere possible for speeding up the execution of my code,by maintaining this logic.
My proposal should be the following but I need your kind opinion.
FIELD-SYMBOLS: <fs_#1_line> TYPE LINE OF table1.
FIELD-SYMBOLS: <fs_#2_line> TYPE LINE OF table1.
LOOP AT table1 WHERE f1 = '10' ASSIGNING <fs_#1_line>. (#1)
updates to table1
set c1_filed, c2_filed
LOOP AT table1 ASSIGNING <fs_#2_line>. (#2)
IF <fs_#2_line>-f1 = c1_filed AND
<fs_#2_line>-f2 = c2_filed.
<fs_#2_line>-fx = 'x'.
<fs_#2_line>-fy = 'y'.
<fs_#2_line>-fz = 'z'.
<fs_#2_line>-ft = 't'.
ENDIF.
ENDLOOP. (#2)
ENDLOOP. (#1)
Your kind support is very important for me.
Thanks in advance.
Regards,
Giovanni -
Problem using field symbols in Query...
Hi,
I am fetching the name of the table and field which I will be using in the query using field symbols. But it gives syntax error...
select single OBJECTTABLE OBJECTFIELD into help_numtab from Zobjectname
where OBJECTNAME = P_OBJECT.
field-symbols : <number> type any.
field-symbols : <module> type any.
ASSIGN help_numtab-OBjectfield to <number>.
ASSIGN help_numtab-OBjecttable to <module>.
/* Here <number> = MATNR and <module> = MARA.
select <NUMBER> into table help_item
from <MODULE>
where ERNAM = SY-UNAME.
This gives a syntax error which says <module> is not defined in ABAP DDIC.instead of field symbols, you ccan try this..
select (help_numtab-OBjectfield) into table help_item
from (help_numtab-OBjecttable)
where ERNAM = SY-UNAME.
~Suresh -
Using field symbols in OOPs programming...have ur points.
Hi all,
I want to use field symbols in OOPS programming like this...
But the system is giving me dump....help me.
START-OF-SELECTION.
CREATE OBJECT OBJ.
FIELD-SYMBOLS : <AB> TYPE ANY.
ASSIGN OBJ TO <AB>.
CALL METHOD <AB>->add
EXPORTING
a = 4
b = 6
changing
c = Z
WRITE : / Z.check the code below
TYPES: BEGIN OF t_struct,
col1 TYPE i,
col2 TYPE i,
END OF t_struct.
DATA: dref1 TYPE REF TO data,
dref2 TYPE REF TO data.
FIELD-SYMBOLS: <fs1> TYPE t_struct,
<fs2> TYPE i.
CREATE DATA dref1 TYPE t_struct.
ASSIGN dref1->* TO <fs1>.
<fs1>-col1 = 1.
<fs1>-col2 = 2.
dref2 = dref1.
ASSIGN dref2->* TO <fs2> CASTING.
WRITE / <fs2>.
GET REFERENCE OF <fs1>-col2 INTO dref2.
ASSIGN dref2->* TO <fs2>.
WRITE / <fs2>.
reward points if helpful......... -
Wat is the use of casting in field symbols
wat is the use of casting in field symbols?
When you assign a data object to a field symbol, you can cast to any data type. This means that any area of memory can be viewed as having assumed a given type. You can then address parts of fields symbolically without having to use offset/length addressing.
A cast is performed using the CASTINGaddition of the ASSIGN statement. The CASTINGaddition allows you to assign a data object to a field symbol where the type of the data object is incompatible with that of the field symbol. There are two types of casting: casting with an implicit type declaration and casting with an explicit type declaration.
For details please have a look at below link:
[Casting|http://help.sap.com/saphelp_nw70/helpdata/en/fc/eb3930358411d1829f0000e829fbfe/frameset.htm]
I hope it helps.
Thanks,
Vibha
Please mark all the useful answers -
Field Symbol not assigned Error SAP R3 46c
Good day,
so what i want is:
assigning a component of a field symbol to another field-symbol to access its values.
This works very well in SAP 47 releases but doesn t work in sap 46c or do i do something wrong?
REPORT Z_GL_FIELDSYMBOLS .
Data:
begin of mytest,
int type i,
int2 type i,
end of mytest,
l type string.
Field-Symbols: <f> type any,
<g> type any.
Start-of-selection.
assign mytest to <f>.
l = '<f>-int'.
assign (l) to <g>.
<g> = '1'.
write :/ <g>.
end-of-selection.
Is there any way to do what i want to do apart from the statement "CREATE SUBROUTINE POOL"?the only problem is:
i know the components of the structure only at runtime, i.e.
i don´t know if my field 'int' exists. perhaps its name is 'intsomewhat', you know?
so i have to do a dynamic assign...
You have to know,
in my actual coding i assigned a reference to a data object to the field symbol..
thus,
something like
assign dref->* to <fs>
was done.
now i want to access single components of the field symbol.
the name of the components are known and are stored in a string.
hmmmm.
so the string contains something like '-MATNR'.
if i assign this string to a field-symbol nothing happens
in my system.
the same coding works without an error in a 47 system.
Message was edited by: Gideon Lenz -
hi gurus..
i would like to know about the importance and usage of filed symbols..
and how it ll help ful during upgradation form ecc4.6c to ecc 6.0..
please help me by giving need ful info
advance thanks..
have a nice time
kranthi kumar .palleP618964 wrote:>
> hi gurus..
> i would like to know about the importance and usage of filed symbols..
> and how it ll help ful during upgradation form ecc4.6c to ecc 6.0..
> please help me by giving need ful info
> advance thanks..
> have a nice time
> kranthi kumar .palle
hi,
Field symbols are placeholders or symbolic name (alias) for other fields (for data objects).
They are similar to dereference pointers in C, which allow you to access data objects dynamically .
When ever you have addressed a Field symbol in your program ,you are addressing to the field that is assigned to the field symbol. You can work with the field symbols in the same way as with the object itself.
Field symbols do not physically reserve space for a field ,but points to its contents.
We can declare a field symbol using the statement
FIELD-SYMBOLS <FS> [ <type> | STRUCTURE <s> DEFAULT <wa> ]. For field symbols angular brackets are part of the syntax
You can create field symbols either without or with type specification.
If you do not specify a type ,the field symbol inherits all of the technical attributes of the field assigned to it .
If you do specify a type , the system checks the compatability of the field symbol and the field you are assigning to it during the ASSIGN statement, else there is a possibility of Run time error .
please reward if it helps.
thanks
Edited by: Lokesh Tripathi on Jul 9, 2008 9:17 AM
Edited by: Lokesh Tripathi on Jul 9, 2008 9:20 AM -
Field-symbols v/s Object references in OO-ABAP
Hi,
can anyone please tell me what is the difference between using field-symbols and object references in OO ABAP? Is there a specific need for field-symbols now that we have references?
Thanks.
Shakul.Hi ,
Please note that both Field symbols & Object References are different .
You can use Field symbols during the following situations
1) When you want to modify the value of internal table, the field symbol would be useful since you do not have to use any Modify statement as in case of work area. The Field symbol works as a pointer and any changes to the field symbol will directly affect the value of the internal table
2) Make sure that you do not reassign the field symbol within a Loop iteration
3) Field symbols are useful when you work with dynamic internal tables ( tables whose structure is determined during run time)
4) After Read an internal table ( Read itab...) into a Field symbol, make sure you do a Sy-subrc check or check if the field symbol is assigned.IF not this will give you a run time error
You can use Object References while creating an object to a class. They are instances of a class.
Thanks,
Chakram Govindarajan -
FieldStrings, field-symbols and matchcode objects
Hi,
Can u explain and give 1 example of each....
1. fieldstring
2. fieldsymbol
3. matchcode object.
Thanks,
NidhiFIELD-SYMBOLS . Its first component is assigned to the field symbol. GET REFERENCE is then used to get a reference to the second component not the structured data object in dref2. It is dereferenced without casting.
Ref link:
http://help.sap.com/saphelp_nw2004s/helpdata/en/43/41341147041806e10000000a1553f6/frameset.htm
https://forums.sdn.sap.com/click.jspa?searchID=-1&messageID=3068811
http://help.sap.com/saphelp_nw04/helpdata/en/fc/eb3860358411d1829f0000e829fbfe/content.htm
http://www.sts.tu-harburg.de/teaching/sap_r3/ABAP4/field_sy.htm
http://searchsap.techtarget.com/tip/1,289483,sid21_gci920484,00.html
Matchcodes are defined in two stages in Abap/4 Dictionary:
1) The revelant table and fields are stipulated in matchcode object. A matchcode object describes the set of all possible search paths for a search item.
2) One or more matchcode ID can be defined for a matchcode object. A matchcode ID describes a special search path for a search term.The fields or combination of fields via which the search is to take place is defined in the matchcode ID.
Matchcodes are replaced by SEARCH HELPs in latest versions
see the doc
1) Elementary search helps describe a search path. The elementary search help must define where the data of the hit list should be read from (selection method), how the exchange of values between the screen template and selection method is implemented (interface of the search help) and how the online input help should be defined (online behavior of the search help).
2) Collective search helps combine several elementary search helps. A collective search help thus can offer several alternative search paths.
3)An elementary search help defines the standard flow of an input help.
4) A collective search help combines several elementary search helps. The user can thus choose one of several alternative search paths with a collective search help.
5)A collective search help comprises several elementary search helps. It combines all the search paths that are meaningful for a field.
6)Both elementary search helps and other search helps can be included in a collective search help. If other collective search helps are contained in a collective search help, they are expanded to the level of the elementary search helps when the input help is called.
CREATION:
Go to SE11 Tcode
select search help
give the 'z' search help name and create
select the selection method ur table name eg : 'mara'
dialog module 'display value immediately'.
add the field whatever u want and lpos = 1 and spos = 1 and check import and export parameter.
where left position when displaying and spos = search position
and then save and activate ..
See the links:
http://help.sap.com/saphelp_nw04/helpdata/en/cf/21ee38446011d189700000e8322d00/content.htm
http://help.sap.com/saphelp_nw04/helpdata/en/cf/21ee45446011d189700000e8322d00/content.htm
https://forums.sdn.sap.com/click.jspa?searchID=3173469&messageID=2176485
https://forums.sdn.sap.com/click.jspa?searchID=3173469&messageID=3601619
pls go through this for search help creation
http://help.sap.com/saphelp_nw2004s/helpdata/en/41/f6b237fec48c67e10000009b38f8cf/content.htm
http://help.sap.com/saphelp_nw04/helpdata/en/cf/21ee2b446011d189700000e8322d00/content.htm
Search Help Exits:
http://help.sap.com/saphelp_nw04/helpdata/en/cf/21ee52446011d189700000e8322d00/content.htm
http://www.sapdevelopment.co.uk/dictionary/shelp/shelp_exit.htm
https://forums.sdn.sap.com/click.jspa?searchID=4390517&messageID=1712818
Collective search help Combine several elementary search helps. A collective search help thus can offer several alternative search paths.
A Collective search help provides alternative search
Paths by combining elementary search helps.
Only one search help can be attached to a field, table or data element. Several search paths are therefore attached with a collective search help.
A collective search help also has interface parameters like
an elementary search help.
Like an elementary search help, a collective search help has an interface of IMPORT and EXPORT parameters with which the search help exchanges data. Using this interface, the collective search help can be attached to fields, tables and data elements exactly like an elementary search help.
Parameter assignment needs to be done for each of the
Included search helps.
When you define a collective search help, there are no components for describing the dialog behavior and data selection; instead the included search helps are listed here. You must assign the parameters of the collective search help to the interface parameters of the included search help for each inclusion.
User may choose the tab and thus the elementary
search maethod.
When we execute the search help SCUSTOM, we are confronted with a dialog which gives us an option of either restricting
By 1)Search for customer according to booking
2)Search for customer according to name.
These are effectively the elementary search helps (SCUSTOM_BOOK and SCUSTOM_NAME) which have been included in the collective search help SCUSTOM.
HOT KEY
The hot key is used to select the elementary search help from the collective search help and to enter the restrictions in the dialog box for restricting values directly from the entry field. If the user often searches for values using the same search help, this procedure can save time.
Steps to create a Collective Search Help
1)Enter the search help name and click on create.
2)Choose Collective search help radio button option as the search help type.
3)Enter the search help parameters.
4)Instead of the selection method, we enter the included
search helps for the collective search help.
5)We need to assign parameters for each of the included
search helps.
6)Complete the parameter assignment by clicking on the push button
7)Collective search help offers the user to obtain F4 help
using any of the included search helps.
Field string is nothing but the group of fields
You can call it as Structure also
example:
types: begin of x_str
kunnr type kunnr,
lifnr type lifnr,
name1 type name1,
land1 type land1,
end of x_str.
this stores one record at run time.
Reward points,
shakir
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