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

Question

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.

In my case I was not injecting a property (@ConfigProperty) but creating a new instance, so at the end I just needed to create a no-args constructor, in order to have two constructors at the end. The other option was to create a Producer but that seems more complex. — Edenshaw
– Edenshaw, Commented Jun 2, 2023 at 20:36

Ladicek · Accepted Answer · 2022-12-30 17:21:59Z

3

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).

answered Dec 30, 2022 at 17:21

Ladicek

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1 Comment

Furious Gamer Over a year ago

You are 100% correct, i forgot to came back to post my own solution (apologies). I came back with a fresh pair of eyes this morning and instantly noticed that the container wouldn't know what to inject for a string by itself. Thank you for posting this, as others may stumble across this issue while not noticing this.

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