How to Effectively Pass Parameters to Queries in JasperReports Using $P{} and $P!{} Syntax?

Query parameter passing in JasperReports

In JasperReports, passing parameters to queries is crucial for customizing report content. Parameters allow dynamic filtering, sorting, and data retrieval based on user input. There are two main syntax expressions for parameter references: $P{} and $P!{}.

$P{paramName} Syntax

The

$P{paramName} syntax is mainly used to set input parameter values ​​in the WHERE clause. It supports various data types, and the replacement algorithm automatically formats parameter values ​​accordingly, such as using quotes for strings and converting integers to numeric values.

$P!{paramName} Syntax

The

$P!{paramName} syntax is used for simple substitutions, usually replacing the parameter value directly in the query without any formatting or type conversion. It allows more flexible handling of parameters.

Example

Suppose you want to parameterize a query to filter the companies table based on a user-selected WHERE clause and sort criteria. The following query can be used:

<code class="language-sql">SELECT name, phone, email
FROM company
WHERE $P!{clause} = $P{key}
ORDER BY $P!{order}</code>

In this example:

• $P!{clause} is a string parameter representing the user-specified WHERE clause.
• $P{key} is a string parameter containing the search keyword entered by the user.
• $P!{order} is a string parameter that determines the sorting conditions.

By using the $P!{} syntax for the WHERE clause, you can allow users to enter arbitrary expressions without having to worry about formatting or type conversion issues. The $P{} syntax is used to search for keywords, making sure they are quoted correctly.

Summary

Understand the $P{} and $P!{} syntax to effectively pass parameters to queries in JasperReports, enabling dynamic and customizable report generation to meet the needs of end users.

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