Question

I have a class which will have a list of commands that it must execute one after another. Commands may be repeated and I don’t want to create a bean for each Command.

What I have in mind is something like:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="parent" class="Parent">
    <property name="commands">
        <list value-type="Command">
            <value>OneCommand</value>
            <value>OtherCommand</value>
            <value>OneCommand</value>
        </list>
    </property>
</bean>
</beans>

And for each value the constructor of the class is called and a new Command object added to the list.

Thing is that when I run a test with that xml file the following exception:

...

Caused by: java.lang.IllegalStateException: Cannot convert value of type [java.lang.String] to required type [org.fideliapos.middleoffice.provisioning.ProvisioningCommand] for property 'commands[0]': no matching editors or conversion strategy found
at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:231)
at org.springframework.beans.TypeConverterDelegate.convertToTypedCollection(TypeConverterDelegate.java:520)
at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:173)
at org.springframework.beans.BeanWrapperImpl.convertIfNecessary(BeanWrapperImpl.java:447)
... 42 more

What am I doing wrong? How can I get spring to call the constructor?

Answer 1

You may create a class implementing PropertyEditorSupport so that Spring knows how to convert from a String to your custom domain object.

Example:

public class CommandPropertyEditor extends PropertyEditorSupport {
  public void setAsText(String text) {
    // create a command from the given text
    Command command = Command.createFromString(text);
    setValue(command);
  }
}

And then reference it for Spring:

<bean class="org.springframework.beans.factory.config.CustomEditorConfigurer">
  <property name="customEditors">
    <map>
      <entry key="Command" value="CommandPropertyEditor"/>
    </map>
  </property>
</bean>