Working with Table-Row Conditional Blocks

What is this page about?

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

A table-row conditional block is a conditional block which body occupies single or multiple rows 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 first occupied row and ends at the end of the last occupied row as follows.

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

<<if ...>> ...	...	...
...	...	...
<<elseif ...>> ...	...	...
...	...	...
<<else>> ...	...	...
...	...	...
...	...	...<</if>>

The following examples in this section are given using client, an instance of the Client class, and clients, an enumeration of instances of the Client class that is defined as follows.

  public class Client
  {
    public String Name { get { ... } }
    public String Country { get { ... } }
    public String LocalAddress { get { ... } }
    ...
  }

Using table-row conditional blocks, you can pick to output a single row among several rows of a single document table depending on a condition like in the following example.

...	...	...
<<if [client.Country == “New Zealand”]>><<[client.Name]>>	<<[client.LocalAddress]>>
<<else>><<[client.Name]>>	<<[client.Country]>>	<<[client.LocalAddress]>><</if>>
...	...	...

You can normally use table-row conditional blocks within data bands to make elements of an enumeration look differently depending on a condition. Consider the following template.

<<foreach [in clients]>><<if [Country == “New Zealand”]>><<[Name]>>	<<[LocalAddress]>>
<<else>><<[Name]>>	<<[Country]>>	<<[LocalAddress]>><</if>><</foreach>>

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

A Company	Australia	219-241 Cleveland St STRAWBERRY HILLS NSW 1427
B Ltd.	Brazil	Avenida João Jorge, 112, ap. 31 Vila Industrial Campinas - SP 13035-680
C & D	Canada	101-3485 RUE DE LA MONTAGNE MONTRÉAL (QUÉBEC) H3G 2A6
E Corp.	445 Mount Eden Road Mount Eden Auckland 1024
F & Partners	20 Greens Road Tuahiwi Kaiapoi 7691
G & Co.	Greece	Karkisias 6 GR-111 42 ATHINA GRÉCE
H Group	Hungary	Budapest Fiktív utca 82., IV. em./28. 2806
I & Sons	43 Vogel Street Roslyn Palmerston North 4414
J Ent.	Japan	Hakusan 4-Chōme 3-2 Bunkyō-ku, TŌKYŌ 112-0001 Japan

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

Also, you can use data bands inside table-row conditional blocks. For example, you can provide an alternate content for an empty table-row data band using the following template.

Client	Country	Local Address
<<if [!clients.Any()]>>No data
<<else>><<foreach [in clients]>><<[Name]>>	<<[Country]>>	<<[LocalAddress]>><</foreach>><</if>>

In case when the corresponding enumeration is empty, the engine produces a report as follows.

Client	Country	Local Address
No data

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

A special case is a template option inside a single-column table row. In such a case, if you put an opening if, elseif, or else tag and a closing if tag in the same cell, the engine treats a template option formed by these tags as a common one rather than a table-row one by default. The following template illustrates such a scenario.

Header

<<if [false]>>Content to remove<</if>>

Footer

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

Header
Footer

However, if needed, you can override this behavior making the engine to treat such a template option as a table-row one by specifying a greedy switch like in the following template.

Header

<<if [false]>>Content to remove<</if -greedy>>

Footer

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

Header
Footer

Note – In the previous examples, tag <<if [false]>> is used for the sake of simplicity; you can use any other Boolean expression instead of just false.

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FAQ

1. Q: How do I write an IF condition inside a table‑row conditional block?
   A: Use the <<if [condition]>> syntax where condition is any Boolean expression that can reference fields of the current data source, e.g., <<if [Country == "New Zealand"]>>. Close the block with << /if>>. The block’s rows will be rendered only when the condition evaluates to true.

2. Q: What is the purpose of the -greedy switch?
   A: When the opening and closing IF tags are placed in the same table cell, the engine treats the block as a common conditional block by default. Adding -greedy (e.g., <<if [false]>> … << /if -greedy>>) forces the engine to treat it as a table‑row conditional block, so the entire row is considered part of the condition.

3. Q: Can I nest a data band inside a table‑row conditional block?
   A: Yes. You can place a <<foreach>> or other data band inside the body of a table‑row conditional block. This is useful for showing alternate content when the enumeration is empty, as demonstrated in the “No data” example.

4. Q: Are table‑row conditional blocks allowed inside table‑column data bands?
   A: No. Nesting a table‑row conditional block inside a table‑column data band or another conditional block is prohibited. Only table‑column data bands and conditional blocks may be nested inside a table‑row conditional block.

5. Q: How can I display a message when the data source for a table‑row block is empty?
   A: Use an IF condition that checks the enumeration, e.g., <<if [!clients.Any()]>>No data<<else>> followed by the normal <<foreach>> loop. The “No data” row will be rendered only when the collection is empty.