--- title: "Working with Table-Column Conditional Blocks" --- {{% alert color="grey" %}} ## Purpose Summary This page explains how to work with table-column conditional blocks in templates. {{% /alert %}} 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. {{< highlight csharp >}} public class Person { public String Name { get { ... } } public int Age { get { ... } } public String Representative { get { ... } } ... } {{< /highlight >}} 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 a `TemplateException` indicating an unknown field 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., `<>No data<>...<>`. 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. `<>`. 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 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. 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. `<>No data<>...<>`. 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 `<>` to hide/show the column.