org.jooq

Interface Template

Deprecated.

- This type is still very experimental and not yet released to a broad public. Do not use this type yet.

@Deprecated
public interface Template

A functional interface to return custom QueryPart objects from input.

This interface is used for templating in jOOQ. Any type of QueryPart can be created through templating mechanisms. Depending on the template, some input data is needed - for example an array or a collection of bind values.

Simple examples of templates are plain SQL construction templates, which are used by jOOQ internally for all plain SQL factory methods. More sophisticated examples include XSL transformation templates, MyBatis templates, etc.

An example using Apache Velocity is given here:

 class VelocityTemplate implements Template {
     private final String file;

     public VelocityTemplate(String file) {
         this.file = file;
     }

     public QueryPart transform(Object... input) {
         VelocityEngine ve = new VelocityEngine();
         ve.setProperty(RuntimeConstants.RESOURCE_LOADER, "file");
         ve.setProperty(RuntimeConstants.FILE_RESOURCE_LOADER_PATH, new File("authors-and-books.vm").getAbsolutePath());
         ve.setProperty(RuntimeConstants.FILE_RESOURCE_LOADER_CACHE, "true");
         ve.init();

         VelocityContext context = new VelocityContext();
         context.put("p", input);

         StringWriter writer = new StringWriter();
         ve.getTemplate(file, "UTF-8").merge(context, writer);
         return DSL.queryPart(writer.toString(), input);
     }
 }
 

And then:

 DSL.using(configuration)
    .resultQuery(new VelocityTemplate("authors-and-books.vm"), 1, 2, 3)
    .fetch();
 

With the contents of authors-and-books.vm being

 SELECT
   a.first_name,
   a.last_name,
   count(*)
 FROM
   t_author a
 LEFT OUTER JOIN
   t_book b ON a.id = b.author_id
 WHERE
   1 = 0
 #foreach ($param in $p)
   OR a.id = ?
 #end
 GROUP BY
   a.first_name,
   a.last_name
 ORDER BY
   a.id ASC
 

Author:

Lukas Eder

Method Summary

Modifier and Type	Method and Description
QueryPart	transform(java.lang.Object... input) Deprecated. Transform some input data into a QueryPart.

Method Detail

transform

QueryPart transform(java.lang.Object... input)

Deprecated.

Transform some input data into a QueryPart.