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 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 <<[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

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 <<[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.

Limitations and Considerations

Limitations and considerations for table-column conditional blocks include:

  • Nesting restrictions: Table-column conditional blocks can contain table-column data bands, but they cannot contain table-row data bands or table-row conditional blocks. Attempting to nest table-row constructs inside a table-column conditional block will raise a template-validation error.

  • Horizontal switch requirement: The -horz switch is required for column-level conditional logic. Without it, the conditional block operates on rows instead of columns, so columns will not be hidden or shown as intended.

  • Field validation: The engine throws an InvalidOperationException saying that it cannot get the value of the member when the condition expression references a property that does not exist in the data source. Ensure property names match exactly (case-sensitive) the members of the object supplied to the reporting engine.

  • Empty collection handling: When using table-column data bands with collections, provide alternate content for empty collections using conditional blocks that check with the Any() method, e.g., <<if [!persons.Any()] -horz>>No data<<else>>...<</if>>.

Note that table-column conditional blocks themselves can be nested inside table-row data bands and conditional blocks.

FAQ

  1. 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.

  2. 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.

  3. Q: What happens if the condition expression references a property that does not exist in the data source?
    A: The engine throws an InvalidOperationException saying that it cannot get the value of the member. Ensure that the property name matches exactly (case‑sensitive) the members of the object supplied to the reporting engine.

  4. 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.

  5. 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