@ConditionalOnExpression not working but @Value working

Question

I have the need of enable/disable a @Aspect on a class in a Spring (non boot) application.

Spring version is: 4.1.6.RELEASE

I have a .properties file ( that we already use successfully in other point of the application, for example to select the log4j2 configuration file ) with the property aspect.enabled=true|false and I tried using the @ConditionalOnExpression annotation to enable|disable it.

This is my try:

application.properties file:

aspect.enabled=true

Class code:

@Configuration
@PropertySource(ignoreResourceNotFound = true, value = { "file:${catalina.home}/conf/application.properties" })
@ConditionalOnExpression("'${aspect.enabled}'=='true'")
@Aspect
@Component
public class TimingProfilerProduction {

    @Value("${aspect.enabled}")
    public String aspect;

With this configuration the expression is always evaluated to false .

I tried putting a single "true" to see if it works in this simple way:

@Configuration
@PropertySource(ignoreResourceNotFound = true, value = { "file:${catalina.home}/conf/application.properties" })
@ConditionalOnExpression("true")
@Aspect
@Component
public class TimingProfilerProduction {

    @Value("${aspect.enabled}")
    public String aspect;

Of course in this way the @ConditionalOnExpression gets evaluated to true and I can also prove that the aspect class property correctly reads the aspect.enabled property.

Try #3

I tried with a @ConditionalOnProperty :

@Configuration
@PropertySource(ignoreResourceNotFound = true, value = { "file:${catalina.home}/conf/application.properties" })
@ConditionalOnProperty(prefix="aspect", name="enabled", havingValue = "true")

but nothing, always false .

Try #4:

@ConditionalOnExpression("${aspect.enabled}")

or

@ConditionalOnExpression("!${aspect.enabled}")

Gives an error:

Caused by: org.springframework.expression.spel.SpelParseException: EL1041E:(pos 1): After parsing a valid expression, there is still more data in the expression: 'lcurly({)'

Try #5 (with default values):

@ConditionalOnExpression("${aspect.enabled:true}")

always gives true (even with aspect.enabled=false ), and accordingly

@ConditionalOnExpression("${aspect.enabled:false}")

always gives false

Answer 1

Instead of:

@ConditionalOnExpression("'${aspect.enabled}' == 'true'")

Try:

@ConditionalOnExpression("${aspect.enabled} == true")