Working with Table-Column Conditional Blocks

A table-column conditional block represents a conditional block, which body occupies a rectangular area of cells of a single document table. The body of such a block (as well as the body of its every template option) starts at the beginning of the top‑left cell of a corresponding area and ends at the end of its bottom‑right cell. Typically, this area consists of one or several table columns as follows.

Note – Table cells occupied by different template options in the following templates are highlighted with different colors.

...	<<if ... -horz>> ...	<<elseif ...>> ...	...	<<else>> ...	...	...	...
...	...	...	...	...	...	...	...
...	...	...	...	...	...	...<</if>>	...

Note – The horz switch instructs the engine to affect table columns rather than rows.

However, unlike table-row conditional blocks able to capture only whole rows, table-column conditional blocks can occupy columns even partially as shown in the following template snippet.

...	...	...	...	...	...	...	...
...	<<if ... -horz>> ...	<<elseif ...>> ...	...	<<else>> ...	...	...	...
...	...	...	...	...	...	...	...
...	...	...	...	...	...	...<</if>>	...
...	...	...	...	...	...	...	...

Let us consider typical use cases for table-column conditional blocks at first defining showRepresentatives, a Boolean value, and person and persons, an instance and an enumeration of instances of the Person class respectively, where the Person class is defined as follows.

public class Person

{
	public String getName() { ... }
	public int getAge() { ... }
	public String getRepresentative() { ... }
	...
}

The most typical scenario for table-column conditional blocks is showing or hiding a table column depending on a condition. You can do it using a template as follows.

Name	Age	<<if [showRepresentatives] -horz>>Representative
<<[person.getName()]>>	<<[person.getAge()]>>	<<[person.getRepresentative()]>><</if>>

When showRepresentatives is set to true, the engine produces a report as follows.

Name	Age	Representative
Evan Edger	47	Terrence Randolph

When showRepresentatives is set to false, the engine produces a report as follows.

Name	Age
Evan Edger	47

For a table being built using a table-row data band, you can also show or hide a table column depending on a condition like in the following template.

Name	Age	<<if [showRepresentatives] -horz>>Representative<</if>>
<<foreach [p in persons]>><<[p.getName()]>>	<<[p.getAge()]>>	<<if [showRepresentatives] -horz>><<[p.getRepresentative()]>><</if>><</foreach>>

Note – Table-row and table-column regions cannot cross, that is why two table-column conditional blocks with the same condition are required in this case.

When showRepresentatives is set to true, the engine produces a report as follows.

Name	Age	Representative
Evan Edger	47	Terrence Randolph
Kate Abrams	35

When showRepresentatives is set to false, the engine produces a report as follows.

Name	Age
Evan Edger	47
Kate Abrams	35

Table-column conditional blocks can also be used to provide different views for a table column depending on a condition. You can use a template as follows to achieve this.

Name	<<if [person.getRepresentative() == “”] -horz>><<[person.getName()]>>	<<else>><<[person.getName()]>>
Representative		<<[person.getRepresentative()]>><</if>>

When a representative is present for a person, the engine produces a report as follows.

Name	Evan Edger
Representative	Terrence Randolph

When a representative is not specified for a person, the engine produces a report as follows.

Name	Kate Abrams
Representative

You can use a similar approach to provide different views for columns of a table being built using a table-column data band. A template for this may look as follows.

Name	<<foreach [p in persons] -horz>><<if [p.getRepresentative() == “”] -horz>><<[p.getName()]>>	<<else>><<[p.getName()]>>
Representative		<<[p.getRepresentative()]>><</if>><</foreach>>

In this case, the engine produces a report as follows.

Name	Evan Edger	Kate Abrams
Representative	Terrence Randolph

Note – You can use common conditional blocks within table-column data bands as well.

In addition, table-column conditional blocks can contain table-column data bands. This is useful, for example, for providing alternate content for an empty table-column data band as shown in the following template.

Name	<<if [!persons.any()] -horz>>No data	<<else>><<foreach [p in persons] -horz>><<[p.getName()]>>
Representative		<<[p.getRepresentative()]>><</foreach>><</if>>

When the enumeration of persons is not empty, the engine produces a report as follows.

Name	Evan Edger	Kate Abrams
Representative	Terrence Randolph

When there is no person at all, the engine produces a report as follows.

Name	No data
Representative

Note – Table-column conditional blocks can themselves be nested to table-row data bands and conditional blocks, but not conversely: Nesting of table-row data bands and conditional blocks into table-column conditional blocks is forbidden.

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FAQ

1. Q: How do I hide or show a whole table column with a conditional block?
   A: Use a table‑column conditional block with the -horz switch and place the condition inside <<if … -horz>> … <<else>> … <<endif>>. When the Boolean variable (e.g., showRepresentatives) is true, the column content is rendered; otherwise the column is omitted.

2. Q: What does the -horz switch do in a conditional block?
   A: The -horz switch tells the reporting engine to apply the conditional logic to table columns instead of rows. Without it, the block would affect whole rows, which is the default behavior for table‑row conditional blocks.

3. Q: Can I nest a table‑column conditional block inside a table‑column data band?
   A: Yes. Table‑column conditional blocks may contain table‑column data bands, allowing you to provide alternate content (e.g., “No data”) when the data band is empty.

4. Q: Is it possible to place a table‑column conditional block inside a table‑row conditional block?
   A: No. Nesting a table‑row conditional block or data band inside a table‑column conditional block is prohibited. The allowed nesting direction is only from column blocks to row blocks, not the reverse.

5. Q: How can I provide an alternative view when a column’s data source is empty?
   A: Use an if condition that checks the collection with !collection.any() inside a table‑column conditional block. For example: <<if [!persons.any()] -horz>>No data<<else>> <<foreach [p in persons] -horz>> … <<endif>>. This renders “No data” when the collection is empty and the normal column content otherwise.