VIEWS Functions


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Programming a BEA Tuxedo Application Using FML

VIEWS Functions

Fvftos

This function transfers data from a fielded buffer to a C structure using a specified view description.

int
Fvftos(FBFR *fbfr, char *cstruct, char *view)

Here:

fbfr is a pointer to a fielded buffer.
cstruct is a pointer to a structure.
view is a pointer to a view name string.

If the named view is not found, Fvftos returns -1, and Ferror is set to FBADVIEW.

When data is being transferred from a fielded buffer to a C structure, the following rules apply:

If a field in the fielded buffer is not mapped to a C structure member, the field is ignored.
If a field is not in the fielded buffer, but appears in the view description and is mapped to a structure member, the corresponding null value is copied into the member.
If a field in the fielded buffer contains data of type string or carray, characters are copied into the structure up to the size of the mapped structure member (that is, source values that are too long are truncated). If the source value is shorter than the mapped structure member, the remainder of the member value is padded with null (0) characters. String values are always terminated with a null character (even if this means truncating the value).
If the number of occurrences of a field in the buffer is equal to the number of mapped structure members, then the fielded data is copied into the C structure.
If the number of occurrences of a field in the buffer is greater than the number of mapped structure members, then the fielded data is ignored.
If the number of occurrences of a field in the buffer is less than the number of mapped structure members, then the extra members are assigned the corresponding null value.

For example, the following code puts string1 into cust.action[0] and abc into cust.bug[0]. All other members in the cust structure should contain null values.

#include <stdio.h>
#include "fml.h"
#include "custdb.flds.h"
#include "custdb.h"
struct custdb cust;
FBFR *fbfr;
. . .
fbfr = Falloc(800,1000);
Fvinit((char *)&cust,"custdb");    /* initialize cust */
str = "string1";
Fadd(fbfr,ACTION,str,(FLDLEN)8);
str = "abc";
Fadd(fbfr,BUG_CURS,str,(FLDLEN)4);
Fvftos(fbfr,(char *)&cust,"custdb");
. . .

View custdb is defined in VIEWS Examples in FML and VIEWS Examples.

For more information, refer to Fvftos, Fvftos32(3fml) in the BEA Tuxedo FML Function Reference.

Fvstof

This function transfers data from a C structure to a fielded buffer using a specified view description.

int
Fvstof(FBFR *fbfr, char *cstruct, int mode, char *view)

Here:

fbfr is a pointer to a fielded buffer.
cstruct is a pointer to a structure.
mode is one of the following: FUPDATE, FJOIN, FOJOIN, or FCONCAT.
view is a pointer to a view name string.

The transfer process obeys the rules listed under the FML function corresponding to the mode parameter: Fupdate, Fjoin, Fojoin, or Fconcat.

If the named view is not found, Fvstof returns -1, and Ferror is set to FBADVIEW.

Note: Null values are not transferred from a structure member to a fielded buffer. That is, during a structure-to-field transfer, if a structure member contains the (default or user-specified) null value defined for that member, the member is ignored.

For more information, refer to Fvftos, Fvftos32(3fml) in the BEA Tuxedo FML Function Reference.

Fvnull

Fvnull is used to determine whether an occurrence in a C structure contains the null value for that field.

int
Fvnull(char *cstruct, char *cname, FLDOCC oc, char *view)

Here:

cstruct is a pointer to a structure.
cname is a pointer to the name of a structure member.
oc is the index to a particular element.
view is a pointer to a view name string.

Fvnull returns:

1 if an occurrence is null
0 if an occurrence is not null
-1 if an error occurred

For more information, refer to Fvnull, Fvnull32(3fml) in the BEA Tuxedo FML Function Reference.

Fvsinit

This function initializes all elements in a C structure to their appropriate null value.

int
Fvsinit(char *cstruct, char *view)

Here:

cstruct is a pointer to a structure.
view is a pointer to a view name string.

For more information, refer to Fvsinit, Fvsinit32(3fml) in the BEA Tuxedo FML Function Reference.

Fvopt

This function allows users to change flag options at run time.

int
Fvopt(char *cname, int option, char *view)

Here:

cname is the name of a structure member.
option is one of the options listed below.
view is a pointer to a view name string.

The following list describes possible values for the option parameter.

F_FTOS: Allows one-way mapping from fielded buffers to C structures. Similar to the S option in view descriptions.
F_STOF: Allows one-way mapping from C structures to fielded buffers. Similar to the F option in view descriptions.
F_BOTH: Allows two-way mapping between C structures and fielded buffers.
F_OFF: Turns off mapping of the specified member. Similar to the N option in view descriptions.

Note that changes to view descriptions are not permanent. They are guaranteed only until another view description is accessed.

For more information, refer to Fvopt, Fvopt32(3fml) in the BEA Tuxedo FML Function Reference.

Fvselinit

This function initializes an individual member of a C structure to its appropriate null value. It sets the ACM of the element to 0, if the C flag is used in the view file; it sets the ALMs to the length of the associated null value, if the L flag is used in the view file.

int
Fvselinit(char *cstruct, char *cname, char *view)

Here:

cstruct is a pointer to a structure.
cname is a pointer to the name of a structure member.
view is a pointer to a view name string.

For more information, refer to Fvselinit, Fvselinit32(3fml) in the BEA Tuxedo FML Function Reference.