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Transformations

Fields within a View Definition may specify an optional transformation. Only Transformations that manipulate the source data are supported in output.

A transformation definition follows the field’s length attribute and has the following format:

Xform(transform [, parameter-list])

where

transform

is one of the following:

APPEND: Appends the current field with the target field by removing trailing spaces from the target field and adding the current field. (input only)
APPEND-STRING: Appends a character string by removing all trailing space and adding the string. The
parameter-list
contains the character string. (input only)
CONCATENATE: Concatenate the current field with the target field by removing trailing spaces from the target field, adding a space, and adding the current field. (input only)
FILL: Fills the target field with a given pattern. The parameter-list contains the character string pattern.
INSERT-CONSTANT: Inserts a character string into a field. The parameter-list contains the character string.
INSERT-FIELD: Inserts the current field to the target field at a specified fixed offset. (input only)
LOWERCASE: Convert a character field to lower case.
UPPERCASE: Convert a character field to upper case.
USER-EXIT: Calls a user-specified routine to perform the transformation. Refer to the Transformation User-Exit section for more details.

Transformation can be applied to both input and output processes.

Multiple transformations can be defined on a single field. They are processed in the order of specification (ie left to right).

A source field can populate multiple target fields by using the following syntax:


FIELD=name,format,length,Xform(transform[,parameter-list]),
                          Xform(transform[,parameter-list])

Example:


FIELD=Lname, C, 15, Xform(INSERT-FIELD, "target LNAME1"),
                     Xform(INSERT-FIELD, "target LNAME2")

The contents of field

Lname

will be copied to fields

LNAME1

and

LNAME2

in the Clustering IDT.

Append Syntax

The Append transform has the following syntax:

Xform (APPEND, "target field-name, order")

field-name

specifies the field to which the current field will be appended.

order

specifies the order in which to append multiple fields to

field-name

. Specify a number, starting from 1.

Example:


FIELD=Name1, C, 45, Xform(APPEND, "target NAME,1")
FIELD=Name2, C, 45, Xform(APPEND, "target NAME,2")

All trailing blanks from field

Name1

will be removed and

Name2

will be appended to it and the result inserted into the field

NAME

Append-String Syntax

The Append transform has the following syntax:

Xform (APPEND-STRING, "string")

string

will be appended to the source field string and copied to the target field.

Example:

FIELD=Surname, C, 15, Xform(APPEND-STRING, ":")

The character ":" will be appended to the

Surname

field.

Concatenate Syntax

The Concatenate transform has the following syntax:


Xform (CONCATENATE, "target field-name, order")
or
Xform (CONCAT, "target field-name, order")

The

field-name

specifies the field to which the current field will be concatenated.

order

specifies the order in which to concatenate multiple fields to

field-name

. Specify a number, starting from 1.

Example:


FIELD=Name1, C, 45, Xform(CONCATENATE, "target NAME,1")
FIELD=Name2, C, 45, Xform(CONCATENATE, "target NAME,2")

Name2

will be concatenated to

Name1

and the result inserted into

NAME

Fill Syntax

The Fill transform has the following syntax:

Xform (FILL, "string")

The target field will be populated with the pattern defined in parameter

string

Example:

FIELD=Filler, C, 45, Xform(FILL, "+-+")

The field

Filler

will be filled with the string

"+-+"

repeatedly until the whole 45 characters are used.

A special expression "

Numeric(NUM)

" can be used instead of a literal string. This means that the target field will be filled with the character value of the decimal number

NUM

using the computer’s native character set. For example,

FIELD=Tabs, C, 2, Xform(FILL, Numeric(9))

causes the field

Tabs

to be filled with the tab character (0x09) on computers using the ASCII character set.

Insert-Constant Syntax

The Insert-Constant transform has the following syntax:

Xform (INSERT-CONSTANT, "string")

The

string

will be inserted in the target field.

Example:

FIELD=Title, C, 10, Xform(INSERT-CONSTANT, "hello")

The

Title

field will contain the constant

"hello"

A special expression "

Numeric(NUM)

" can be used instead of a literal string. This means that the first position of the target field will contain the character value of the decimal number

NUM

using the computer’s native character set. For example,

FIELD=TabAndSpaces, C, 3, Xform(INSERT-CONSTANT, Numeric(9))

causes the first byte of the field TabAndSpace to contain a tab character (0x09) on computers using the ASCII character set. The remaining bytes in the field - two in this example - are filled with spaces.

Insert-Field Syntax

The Insert-Field transform has the following syntax:

Xform (INSERT-FIELD, "target field-name, [offset]")

The

field-name

specifies the field to which the current field will be appended at offset. The default value of offset is 0.

Example:


FIELD=Addr1, C, 45, Xform(INSERT-FIELD, "target ADDR")
FIELD=Addr2, C, 45, Xform(INSERT-FIELD, "target ADDR,45")

The contents of

Addr1

will be copied to field

ADDR

at offset 0. The contents of field

Addr2

will be copied to field

ADDR

at offset 45.

Uppercase/Lowercase Syntax

The Uppercase/Lowercase transform has the following syntax:


Xform (UPPERCASE)
Xform (LOWERCASE)

It changes the string in the data to the specified case.

Example:


FIELD=Surname, C, 15, Xform(UPPERCASE)
FIELD=First,   C, 45, Xform(LOWERCASE)

Fields

Surname

and

First

will be converted to upper and lowercase respectively

Transformation User-Exit

A Transform User-Exit (TUE) is used to alter a record prior to insertion into the IDT.

The TUE is called after reading a record from the source file and before any field level transforms have been performed. The TUE is a "record level" exit, meaning that it has access to the entire record. Upon return from the exit, Data Clustering Engine will perform field-level transforms while converting the view record into IDT layout.

The normal use for a TUE is to insert data into a new field. Anew field can be created with the transform by specifying a name, format and length. The field can then be referenced in the TUE.

The TUE is enabled by adding a user-exit transform definition. For example,


VIEW-DEFINITION
*==============
NAME=DATAIN
FIELD=Name,    C, 60
FIELD=Myfield, C, 50, XFORM(user-exit, "mydll myfunc")

defines a field called

Myfield

which can be populated by the user-exit function

myfunc

, which is available in a shared object called

mydll

User-Exits must conform to a specific protocol in order to communicate with Data Clustering Engine. A User-Exit is written in C and compiled and linked as a DLL/shared library. DCE will load the User-Exit and call a predefined entry point when a "service" is required from the exit.

The parameters and other details for Transformation User-Exits are only available on request.

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Table of Contents

User Guide

User Guide

Transformations

Transformations

Append Syntax

Append-String Syntax

Concatenate Syntax

Fill Syntax

Insert-Constant Syntax

Insert-Field Syntax

Uppercase/Lowercase Syntax

Transformation User-Exit