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ABAPREAD_DATASET - READ DATASET
BAL Application Log Documentation ROGBILLS - Synchronize billing plansThis documentation is copyright by SAP AG.
READ DATASET
READ DATASET dset INTO dobj $[MAXIMUM LENGTH mlen$]
$[$[ACTUAL$] LENGTH alen$].
Additions
1. ... MAXIMUM LENGTH mlen
2. ... $[ACTUAL$] LENGTH alen
Effect
This statement transfers data from the file specified in dset to the data object dobj. dobj expects variables with elementary data types and flat structures. The file must be opened using any access type. If a closed or nonexistent file is accessed, a catchable exception is raised. If the file was opened as a text file, dobj must be character-like.
dset expects a character-like data object that contains the
physical name
of the file. The content is read from the file starting from the current file pointer. After the data
is passed, the file pointer is positioned after the section that was read. Using the MAXIMUM LENGTH
addition, the number of characters or bytes to be read from the file can be limited. Using ACTUAL LENGTH, the number of characters or bytes actually read can be determined.
Influence of the Access Type
Files can be read regardless of the access
type. Whether data can be read or not depends solely on the position of the file pointer. If the latter is at the end of the file or after the file, no data can be read and sy-subrc will be set to 4.
Influence of the Storage Type
The import depends on the storage type used to open the file with the statement OPEN DATASET.
- If the file was opened as a text file or as a legacy text file, the data is read from the current position of the file pointer to the next end-of-line marker by default, and the file pointer is positioned after the end-of-line marker. If the last character of a text file is not an explicit end-of-line marker, the end of the text file is interpreted as the end of the line. If the data object dobj is too short for the number of read characters, the superfluous characters and bytes are cut off. If it is longer, it is padded with blanks on the right. If dobj is a string, it only contains the read characters.
- If the file was opened as a binary file or as a legacy binary file, the system reads as much data that can fit into the data object dobj by default. The file pointer is positioned after the read data. If the data object dobj is longer than the number of read characters, it is padded with hexadecimal 0 on the right. If dobj is a string, the system tries to read the data all at once.
If the specified storage type requires conversion, this is performed before the assignment to the data object dobj. Afterwards, the read data is placed, byte by byte, in the data object.
System Fields
Read Text Files
| sy-subrc | Meaning |
| 0 | Data was read up to an explicit end-of-line marker or up to an implicit end-of-line marker at the end of the file. |
| 4 | An attempt was made to read data after the end of the file. |
Read Binary Files
| sy-subrc | Meaning |
| 0 | Data was read either without reaching the end of the of file or the end of the file was reached exactly. |
| 4 | Data was read up to the end of the file and the target field was longer than necessary, or an attempt was made to read data after the end of the file. |
Notes
- The data from the text files can only be imported into character-like data objects and data from binary files should be imported only into byte-like data objects. To evaluate imported data as numeric data objects or mixed structures, it is recommended that these are exported into binary containers and then assigned using the CASTING addition of the ASSIGN statement in accordance with the typed field symbols. If the file is opened as a legacy text file when data like this is being imported, there is the danger that an end-of-line marker is contained in the binary representation of a number and that the number can therefore not be read.
- However, a text file without an explicit end-of-line marker still has an implicit end-of-line marker at the end of the file.
- In an enumerated object, the data objects stored in the file of the
basic type of the enumerated object, whose value is a valid
enumerated value of its
enumerated type,
can be imported. This includes any stored enumerated objects and regular elementary data objects of the basic type. Invalid values raise an exception from the class CX_SY_FILE_IO.
Example
Import of the binary file flights.dat written in the example by the statement TRANSFER.
The data is written in binary form to a byte-like typed field symbol hex_container>. The assignment of the structured
data area wa
to the field symbol applies the length of the data area and imports a corresponding number of bytes
for the loop process. It would be possible to import directly into the structure wa with the
same result, but using the field symbol is the recommended procedure because in this way data is passed explicitly from a binary file to a binary data type.
Addition 1
... MAXIMUM LENGTH mlen
Effect
This addition determines the maximum number of characters or bytes read from the file. mlen expects a data object of the type i that contains the number of characters or bytes. In the case of text files, the content of mlen determines how many characters are read from the file. In the case of binary files, legacy text files, and legacy binary files, mlen determines how many bytes are read from the file.
The first mlen characters or bytes are read from the current position of the file pointer and the file pointer is positioned after the read data. If the file is opened as a (legacy) text file and there is an end-of-line marker within the specified length, data is read only up to this position and the file pointer is positioned after the end-of-line marker.
If the value of mlen is 0, no data is read. If the value of mlen is negative, the addition
is ignored, and the import takes place in the same way as described for Influence of the Storage Type.
Note
In case of text files, the number of bytes read depends on the character format specified using ENCODING when opening the file.
Example
This program section has the same functions as the previous example. Here data is imported not into
a byte-like field symbol, but into a byte-like data object hex_container. The number of bytes to be imported is determined by the typed field symbol spfli>.
Addition 2
... $[ACTUAL$] LENGTH alen
Effect
This addition assigns the number of characters or bytes to be read from the file to the data object alen. The following can be specified for alen:
- An existing variable of the data type i or a variable to which the type i can be converted.
- An inline declaration DATA(var) or FINAL(var), where a variable of type i is declared.
For text files, the system determines how many characters were written to the memory. For binary files, legacy text files, and legacy binary files, the system determines how many bytes were read from the file.
Example
The system field sy-abcde contains 26 characters. A conversion to UTF-16 representation creates
a byte string with 52 bytes. This number is determined using the addition LENGTH and displayed after a file containing the byte chain is read.
Notes
- Regardless of the length of the target field, the number of characters or bytes actually read from the file is always returned.
- The optional addition ACTUAL was introduced to distinguish the addition LENGTH more
effectively from the addition MAXIMUM LENGTH. For this reason, the addition ACTUAL should always be used.
Exceptions
Catchable Exceptions
- Cause: The required conversion is not supported. (For example,
because a language not supported by the conversion was specified using SET LOCALE LANGUAGE.)
Runtime Error: CONVT_CODEPAGE_INIT
- Cause: Conversion is not possible. The data is read as far as possible. Text data where the conversion has failed is undefined (see also note below).
Runtime Error: CONVT_CODEPAGE
- Cause: No authorization for access to file
Runtime Error: OPEN_DATASET_NO_AUTHORITY
- Cause: An error occurred when the file was read.
Runtime Error: DATASET_READ_ERROR
- Cause: File cannot be opened.
Runtime Error: DATASET_CANT_OPEN
- Cause: The file is not open.
Runtime Error: DATASET_NOT_OPEN
- Cause: The file was opened using the addition FILTER and since then a switch of the work process took place.
Runtime Error: DATASET_PIPE_CLOSED
CL_GUI_FRONTEND_SERVICES - Frontend Services ROGBILLS - Synchronize billing plans
This documentation is copyright by SAP AG.
Length: 14197 Date: 20240426 Time: 043912 sap01-206 ( 227 ms )
