how-to-make-programmable-scripts.md

How to make programmable scripts

There are situations when you need to parametrize SQL scripts or create tables dynamically based on some input variables. Darwin supports also this approach using FreeMarker templating library. You'd need to manually add FreeMarker to your Maven or Gradle descriptor because Freemarker is optional library in Darwin.

<dependency>   
    <groupId>org.freemarker</groupId>
    <artifactId>freemarker</artifactId>
    <version>2.3.28</version>
</dependency>

Or Gradle:

dependencies {
    compile 'org.freemarker:freemarker:2.3.28'
}

After linking FreeMarker library you'd need to reconfigure Darwin:

@Bean
public Darwin adam(ApplicationContext applicationContext) {
	final ScriptableResourceAccessor resourceAccessor = new ScriptableResourceAccessor(
			applicationContext, "utf-8", "classpath:/META-INF/adam/sq/"
	);
	final Map<String, Object> variables = new HashMap<>();
	variables.put("prefix", "SOME_PREFIX");
	variables.put("loop_count", 5);
	resourceAccessor.setVars(variables);
	return new DarwinBuilder(applicationContext, "adam", "1.0")
			.withResourceAccessor(resourceAccessor)
			.build();
}

... and then take advantage of the variables in your script:

<#list 0..loop_count as iteration>
create table ${prefix}_ADAM_${(iteration_index + 1)?string} (
	id integer not null auto_increment,
	preciousContent varchar(255) not null,
	constraint CNPK_${prefix}_ADAM_${(iteration_index + 1)?string} primary key (id)
) engine=InnoDB;
</#list>

This setup will create 5 tables:

• SOME_PREFIX_ADAM_1
• SOME_PREFIX_ADAM_2
• SOME_PREFIX_ADAM_3
• SOME_PREFIX_ADAM_4
• SOME_PREFIX_ADAM_5