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springehcachespelevaluationexception

@Cacheble annotation on no parameter method

I want to have @Cacheable annotation on method with no parameter. In that case, I use @Cacheable as follows 

@Cacheable(value="usercache", key = "mykey")
public string sayHello(){
    return "test"
}

However, when I call this method, it doesn't get executed and it get exception as below

org.springframework.expression.spel.SpelEvaluationException: EL1008E:(pos 0): Property or field 'mykey' cannot be found on object of type 'org.springframework.cache.interceptor.CacheExpressionRootObject' - maybe not public?

Please suggest.

Solution

  • It seems that Spring doesn't allow you to provide a static text for the cache key in the SPEL, and it doesn't include as default the name of the method on the key, so, you could be in a situation when two methods using the same cacheName and without a key would potentially cache different results with the same key.

    The easiest workaround is to provide the name of the method as the key:

    @Cacheable(value="usercache", key = "#root.methodName")
public string sayHello(){
return "test"
}

    This would set sayHello as the key.

    If you really need a static key, you should define a static variable in the class, and use #root.target: 

    public static final String MY_KEY = "mykey";

@Cacheable(value="usercache", key = "#root.target.MY_KEY")
public string sayHello(){
return "test"
}

    You can find here the list of SPEL expressions that you can use in your key.