[jira] [Created] (MAHOUT-801) MongoDBDataModel getID() throws a class cast exception

[Vishnu (JIRA)]

MongoDBDataModel  getID() throws a class cast exception
-------------------------------------------------------

                 Key: MAHOUT-801
                 URL: https://issues.apache.org/jira/browse/MAHOUT-801
             Project: Mahout
          Issue Type: Bug
          Components: Integration
    Affects Versions: 0.6
            Reporter: Vishnu


I imported GroupLense ratings.dat to a mongodb collection "ratings" using 
mongoimport 

Output of db.ratings.find() query

"_id" : ObjectId("4e6733621497ef8543c1e144"), "userId" : 1, "movieId" : 1193, 
"rating" : 5, "timestamp" : NumberLong(978300760) 
"_id" : ObjectId("4e6733621497ef8543c1e145"), "userId" : 1, "movieId" : 661, 
"rating" : 3, "timestamp" : NumberLong(978302109) 
"_id" : ObjectId("4e6733621497ef8543c1e146"), "userId" : 1, "movieId" : 914, 
"rating" : 3, "timestamp" : NumberLong(978301968) 
"_id" : ObjectId("4e6733621497ef8543c1e147"), "userId" : 1, "movieId" : 3408, 
"rating" : 4, "timestamp" : NumberLong(978300275) 
"_id" : ObjectId("4e6733621497ef8543c1e148"), "userId" : 1, "movieId" : 2355, 
"rating" : 5, "timestamp" : NumberLong(978824291) 



Spring Bean creating MongoDBDataModel instance

{code}
  <bean id="mongodbDataModel" 
class="org.apache.mahout.cf.taste.impl.model.mongodb.MongoDBDataModel">
        <constructor-arg index="0" type="java.lang.String" value="127.0.0.1"/>
        <constructor-arg index="1" type="int" value="27017"/>
        <constructor-arg index="2" type="java.lang.String" value="grouplens"/>
        <constructor-arg index="3" type="java.lang.String" value="ratings" />
        <constructor-arg index="4" type="boolean" value="false"/>
        <constructor-arg index="5" type="boolean" value="false"/>
        <constructor-arg index="6" type="java.text.DateFormat" value="#{ null 
}"/>
        <constructor-arg index="7" type="java.lang.String" value="user"/>
        <constructor-arg index="8" type="java.lang.String" value="password"/>
        <constructor-arg index="9" type="java.lang.String" value="userId"/>
        <constructor-arg index="10" type="java.lang.String" value="movieId"/>
        <constructor-arg index="11" type="java.lang.String" value="rating"/>
    </bean>
{code}

When MongDBDataModel loads the rating from mongdb, method getID() throws 
ClassCastException

{code}
Caused by: java.lang.ClassCastException: java.lang.Integer cannot be cast to 
java.lang.String
        at 
org.apache.mahout.cf.taste.impl.model.mongodb.MongoDBDataModel.getID(MongoDBDataModel.java:742)
        at 
org.apache.mahout.cf.taste.impl.model.mongodb.MongoDBDataModel.buildModel(MongoDBDataModel.java:564)
        at 
org.apache.mahout.cf.taste.impl.model.mongodb.MongoDBDataModel.<init>(MongoDBDataModel.java:347)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at 
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
        at 
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:513)

{code}

Exception is being thrown by last return statement "return (String) id;"

{code}
private String getID(Object id, boolean isUser) {
    if (id.getClass().getName().contains("ObjectId")) {
      if (isUser) {
        userIsObject = true;
      } else {
        itemIsObject = true;
      }
      return ((ObjectId) id).toStringMongod();
    } else {
      return (String) id;
    }
  }
{code}



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