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https://issues.apache.org/jira/browse/MAHOUT-801?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13102669#comment-13102669
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Fernando Tapia Rico commented on MAHOUT-801:
--------------------------------------------
Hi Vishnu,
I think this change should work:
{code:java}
return (String) id;
{code}
{code:java}
return id.toString();
{code}
> 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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