Getting NullPointerException on MongoTemplate

Question

i'm using Spring + jersey + mongodb(on mongolab) + maven

the web service part is working fine but when i try to connect to the database i get a null pointer exception on the MongoTemplate i've tried a lot of solutions but none working

here is my code:

applicationContext:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
  xmlns:p="http://www.springframework.org/schema/p"
  xmlns:context="http://www.springframework.org/schema/context"
  xmlns:mongo="http://www.springframework.org/schema/data/mongo"
  xsi:schemaLocation="
    http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context.xsd
    http://www.springframework.org/schema/data/mongo
    http://www.springframework.org/schema/data/mongo/spring-mongo-1.0.xsd">


    <context:component-scan base-package="com.jersey" />

    <!-- Factory bean that creates the Mongo instance -->
    <mongo:mongo host="ds031972.mongolab.com" port="31972" id="mongo" />
    <mongo:db-factory dbname="proyecto_desarrollo" username="danprat" password="19693058" mongo-ref="mongo" id="mongoDbFactory" />

    <!-- MongoTemplate for connecting and quering the documents in the database -->
    <bean id="mongoTemplate" class="org.springframework.data.mongodb.core.MongoTemplate">
        <constructor-arg name="mongoDbFactory" ref="mongoDbFactory" />
    </bean>
</beans>

here the dao that uses the mongoTemplate

public class UserManager {

    public static final String COLLECTION_NAME = "user";

    @Autowired
    private MongoTemplate mongoTemplate;

    public List<User> getUsers() {
        return mongoTemplate.findAll(User.class , COLLECTION_NAME);
    }
}

just in case this is the service file

@Path("/users")
public class UserService {

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public List<User> getUsers(){

        UserManager userManager = new UserManager();

        return userManager.getUsers();
    }
}

Connection uri provided by mongolab :

mongodb://<dbuser>:<dbpassword>@ds031972.mongolab.com:31972/proyecto_desarrollo

i believe MongoTemplate is not properly injecting but don't know why im new to spring and mongo

EDIT

this is is the one that worked thanks to the answer given:

@Component
public class UserManager {

    public static final String COLLECTION_NAME = "user";

    @Autowired
    private MongoTemplate mongoTemplate;

    public List<User> getUsers() {
        return mongoTemplate.findAll(User.class , COLLECTION_NAME);
    }
}


@Path("/users")
@Component
public class UserService {

    @Autowired
    UserManager userManager;

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public List<User> getUsers(){


        return userManager.getUsers();
    }
}

xml:

<context:component-scan base-package="com.jersey.persistence" />
<context:component-scan base-package="com.jersey.services" />
<context:component-scan base-package="com.jersey.commons.entities" />
<!-- Factory bean that creates the Mongo instance -->
<mongo:mongo host="ds031972.mongolab.com" port="31972" id="mongo" />
<mongo:db-factory dbname="proyecto_desarrollo" username="danprat" password="19693058" mongo-ref="mongo" id="mongoDbFactory" />

<!-- MongoTemplate for connecting and quering the documents in the database -->
<bean id="mongoTemplate" class="org.springframework.data.mongodb.core.MongoTemplate">
    <constructor-arg name="mongoDbFactory" ref="mongoDbFactory" />
</bean>

Please post the whole stack trace of your NullPointerException. — TimoStaudinger, May 17 '15 at 03:56
Unlike forum sites, we don't use "Thanks", or "Any help appreciated", or signatures on [so]. See "[Should 'Hi', 'thanks,' taglines, and salutations be removed from posts?](http://meta.stackexchange.com/questions/2950/should-hi-thanks-taglines-and-salutations-be-removed-from-posts). BTW, it's "Thanks in advance", not "Thanks in advanced". — John Saunders, May 22 '15 at 21:22
@John Sauders Nice to know that info. Sorry for that mistake english is not my main language. — , May 23 '15 at 00:22
@DanielPrato: it's not an "English" issue. It's a "Stack Exchange" issue. The site is not about discussion: not even _polite_ discussion. — John Saunders, May 23 '15 at 00:23

Robert Moskal · Accepted Answer · 2015-05-21T16:53:11.600

0

I don't think you have your application context set up to properly scan classes like UserManager. UserManager doesn't seem to be annotated with the requisite @Component annotation.

Plus you are probably not scanning your own packages to do the injection. I see

<context:component-scan base-package="com.jersey" />

You need to add the package where UserManager lives, and anything else you need scanned. You can do this by appending additional bases classes separated by commas.

edited May 21 '15 at 16:53

answered May 17 '15 at 03:59

Robert Moskal

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Thank you very much for the answer this was the problem didn't know that annotation was needed and also the base package i thought it was enough to put the basic. – May 17 '15 at 04:19

Getting NullPointerException on MongoTemplate

1 Answers1