Working with Table-Column Conditional Blocks

What is this page about?

This page explains how to work with table-column conditional blocks in templates.

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 Name { get { ... } }

	public int Age { get { ... } }
	
	public String Representative { get { ... } }
	
	...
}

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.Name]>>	<<[person.Age]>>	<<[person.Representative]>><</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.Name]>>	<<[p.Age]>>	<<if [showRepresentatives] -horz>><<[p.Representative]>><</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.Representative == “”] -horz>><<[person.Name]>>	<<else>><<[person.Name]>>
Representative	<<if [person.Representative == “”] -horz>><<[person.Name]>>	<<[person.Representative]>><</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.Representative == “”] -horz>><<[p.Name]>>	<<else>><<[p.Name]>>
Representative		<<[p.Representative]>><</if>><</foreach>>

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

Name	Evan Edger	Kate Abrams
Representative	Terrence Randolph	Kate Abrams

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.Name]>>
Representative	<<if [!persons.Any()] -horz>>No data	<<[p.Representative]>><</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.

FAQ

Q: How do I enable the -horz switch to make a conditional block affect columns instead of rows?
A: Add the -horz flag directly after the condition in the opening tag, e.g. <<if [showColumn] -horz>>. This tells the engine to apply the block to the column range defined by the surrounding cells.
Q: Can I nest a table‑row conditional block inside a table‑column conditional block?
A: No. Table‑column conditional blocks may contain table‑column data bands, but nesting table‑row data bands or row‑level conditional blocks inside a column block is prohibited. Attempting this will raise a template‑validation error.
Q: What happens if the condition expression references a property that does not exist in the data source?
A: The engine throws a TemplateException indicating an unknown field. Ensure that the property name matches exactly (case‑sensitive) the members of the object supplied to the reporting engine.
Q: How can I provide an alternate view when a collection used in a column data band is empty?
A: Use an if block that checks the collection with the Any() method, e.g. <<if [!persons.Any()] -horz>>No data<<else>>...<</if>>. Place the alternate content inside the if branch.
Q: Is it possible to hide a column conditionally without using the -horz switch?
A: The -horz switch is required for column‑level conditional logic. Without it, the if block operates on rows, so the column will not be hidden. Use <<if [condition] -horz>> to hide/show the column.

Working with Table-Row Conditional Blocks