ComputedField Class Reference

Provides access to a ComputedField which is referenced by a DataSource. More...

Public Member Functions
void	dispose () throws TFormerException
	Releases the resources allocated by this instance. More...
void	dump (PrintStream s) throws IOException, TFormerException
	Dumps the current instance into a text stream. More...
Aggregation	getAggregation () throws TFormerException
	Gets the aggregation-type of the ComputedField. More...
String	getComment () throws TFormerException
	Gets the comment for the ComputedField. More...
String	getExpression () throws TFormerException
	Gets the aggregation expression of the ComputedField. More...
String	getFilter () throws TFormerException
	Gets the filter expression of the ComputedField. More...
String	getName () throws TFormerException
	Gets the name of the ComputedField. More...
ComputedField	getNext () throws TFormerException
	Gets the next ComputedField defined in the DataSource. More...
long	getOrder () throws TFormerException
	Gets the evaluation order of the ComputedField. More...
void	setAggregation (Aggregation aggregation) throws TFormerException
	Sets the aggregation-type of the ComputedField. More...
void	setComment (String sComment) throws TFormerException
	Sets the comment for the ComputedField. More...
void	setExpression (String sExpression) throws TFormerException
	Sets the aggregation expression of the ComputedField. More...
void	setFilter (String sFilter) throws TFormerException
	Sets the filter expression of the ComputedField. More...
void	setName (String sName) throws TFormerException
	Sets the name of the ComputedField. More...
void	setOrder (long lOrder) throws TFormerException
	Sets the evaluation order of the ComputedField. More...
String	toString ()
	Returns a string representation of the instance. More...

Detailed Description

Provides access to a ComputedField which is referenced by a DataSource.

Overview

With the help of ComputedFields computations can be centralized in the DataSource instead of performing the computations in the FormLayout. For example, you might

• convert the content of an existing field if the DataSource to uppercase,
• remove leading and trailing spaces,
• concatenate multiple fields of the DataSource into a single one,
• or perform numerical computations like computing the VAT.

The result of a ComputedField is available in the DataSource like any other source-field. In the expression of a ComputedField you may refer to multiple fields of the DataSource. It is also possible to use other ComputedFields already defined in the DataSource in the expression.

Aggregation

In addition, ComputedFields support Aggregation (see ComputedField.setAggregation). Thus it is pretty simple to create serial numbers or to calculate running sums and averages which are not available in a DataSource directly.

Filter Expressions

To exclude specific Records of a DataSource from being considered by the Aggregation use filter expressions.

Member Function Documentation

void dispose

(

)

throws TFormerException

Releases the resources allocated by this instance.

Call this method in every case (even in case of exceptions) is this instance is not required anymore.

void dump

(

PrintStream

s

)

throws IOException, TFormerException

Dumps the current instance into a text stream.

Parameters

s	Instance of the stream

Aggregation getAggregation

(

)

throws TFormerException

Gets the aggregation-type of the ComputedField.

Returns

The aggregation-type of the ComputedField

String getComment

(

)

throws TFormerException

Gets the comment for the ComputedField.

Returns

The comment for the ComputedField

String getExpression

(

)

throws TFormerException

Gets the aggregation expression of the ComputedField.

Returns

The aggregation expression of the ComputedField

String getFilter

(

)

throws TFormerException

Gets the filter expression of the ComputedField.

Returns

The filter expression of the ComputedField

String getName

(

)

throws TFormerException

Gets the name of the ComputedField.

Returns

The name of the ComputedField

ComputedField getNext

(

)

throws TFormerException

Gets the next ComputedField defined in the DataSource.

A DataSource stores a list of ComputedField-objects. To retrieve the first ComputedField in the DataSource see DataSource.getFirstComputedField.

Returns

The next ComputedField object in the list or null

long getOrder

(

)

throws TFormerException

Gets the evaluation order of the ComputedField.

Returns

The evaluation order of the ComputedField

void setAggregation

(

Aggregation

aggregation

)

throws TFormerException

Sets the aggregation-type of the ComputedField.

Parameters

aggregation

The aggregation-type of the ComputedField

void setComment

(

String

sComment

)

throws TFormerException

Sets the comment for the ComputedField.

Parameters

sComment

The comment for the ComputedField

void setExpression

(

String

sExpression

)

throws TFormerException

Sets the aggregation expression of the ComputedField.

Parameters

sExpression

The aggregation expression of the ComputedField

void setFilter

(

String

sFilter

)

throws TFormerException

Sets the filter expression of the ComputedField.

Using a filter expression allows to exclude specific Records from aggregation.

Parameters

sFilter

The filter expression of the ComputedField.

void setName

(

String

sName

)

throws TFormerException

Sets the name of the ComputedField.

Parameters

sName

The name of the ComputedField

void setOrder

(

long

lOrder

)

throws TFormerException

Sets the evaluation order of the ComputedField.

Parameters

lOrder

The evaluation order of the ComputedField

String toString

(

)

Returns a string representation of the instance.

Returns

A string representation of the instance