I have a very curious dependency injection resolve error during compile time. I have a property in application.properties, which i inject via the @ConfigProperty annotation in a Quarkus project. I have multiple @ConfigProperty injections in the project, none of which cause an issue except one. When i compile the project, i get the following maven error:

javax.enterprise.inject.UnsatisfiedResolutionException: Unsatisfied dependency for type java.lang.String and qualifiers [@Default]

To give more details, it states specifically which member is the issue:

java member: com.webscraper.bot.base.builder.ConfigWebScraperBuilder():webScraperClassName [ERROR] - declared on CLASS bean [types=[com.webscraper.bot.base.builder.ConfigWebScraperBuilder, java.lang.Object], qualifiers=[@Default, @Any], target=com.webscraper.bot.base.builder.ConfigWebScraperBuilder]

Usually with an error like this, i would look for missing @ApplicationScoped annotations or such indicating that injected dependency cannot be resolved. However, what is weird here is that it is saying that java.lang.String is the unsatisfied dependency - how is that possible? As i said before, i use the @ConfigProperty annotiation in other places perfectly fine for other basic Java data class types like Long etc. (e.g. for "bot.id" property).

Here is the application.properties:

bot.id = 1
bot.webscraper.className = Test

Here is the class where the error is raised from (i made the webScraperClassName field not private final because i wanted to see whether this is causing injection issues here):

@ApplicationScoped
public class ConfigWebScraperBuilder {
    @ConfigProperty(name = "bot.webscraper.className")
    String webScraperClassName;

    public ConfigWebScraperBuilder(String webScraperClassName) {
        this.webScraperClassName = webScraperClassName;
    }

    public WebScraper buildWebScraperFromConfig() throws Exception {
        Class<?> clazz = Class.forName(webScraperClassName);
        Constructor<?> constructor = clazz.getConstructor(ParserAdapter.class);
        return (WebScraper) constructor.newInstance(new Object[] { new ParserAdapter() });
    }
}

Edit: The @ConfigProperty annotation is imported from org.eclipse.microprofile.config.inject.ConfigProperty and the same one used in other locations where the injection works perfectly fine.

CodePudding user response：

I think this is caused by Quarkus (or ArC, actually) finding a single constructor and hence treating that constructor as the bean constructor. All parameters of the bean constructor are injection points, so ArC tries to resolve a bean of type String with the @Default qualifier (which is implied because no other qualifier is present).

If you want the container to inject a config property into the parameter, add the @ConfigProperty qualifier annotation to the parameter. If you don't want the container to inject anything into a constructor, declare a zero-parameter constructor (and mark it @Inject if you want to keep the other constructor).