Query mapper does not use @Field field name when querying nested fields in combination with nested keywords [DATAMONGO-1406]

[spring-projects-issues]

Hansel DOrnellas opened DATAMONGO-1406 and commented

we have a document class;

@Document(collection = "Computer")
public class Computer
{
   @Id
   private String _id;

   private String batchId;

  @Field("stat")
   private String status;

   @Field("disp")
   private List<Monitor> displays;

   //setters and getters
}

public class Monitor {
   @Field("res")
   private String resolution;

  // setters/getters
}

In MongoTemplate.java, the call to :

protected <S, T> List<T> doFind(String collectionName, DBObject query, DBObject fields, Class<S> entityClass,
			CursorPreparer preparer, DbObjectCallback<T> objectCallback)

DBObject mappedQuery = queryMapper.getMappedObject(query, entity);

resolves the fields to the input query to the ones in the @Field annotations, except for these in embedded arrays. So, in the example above, resolution fields in DBObject remains resolution. While, the status field resolves to stat.

Note the queries in the inner list, are setup as elemMatch.

The query submitted to mongo after getMappedObject is called:

{ "$and" : [ { "stat" : "A"} , { "disp" : { "$elemMatch" : { "$and" : [ { "resolution" : { "$ne" :  null }} , { "resolution" : { "$ne" : ""}}]}}}] , "batchId" : "5d0f1c53-92a2-48cb-8c84-1061769962c1"}

Which doesn't get any data, because there is no field called resolution (the field in mongo is res).
Note: The query input to getMappedObject is:

{ "$and" : [ { "status" : "A"} , { "displays" : { "$elemMatch" : { "$and" : [ { "resolution" : { "$ne" :  null }} , { "resolution" : { "$ne" : ""}}]}}}] , "batchId" : "5d0f1c53-92a2-48cb-8c84-1061769962c1"}

Notice the status and displays fields correctly get converted to the value in the @Field annotation.

The correct query from getMappedObject should be:

{ "$and" : [ { "stat" : "A"} , { "disp" : { "$elemMatch" : { "$and" : [ { "res" : { "$ne" :  null }} , { "res" : { "$ne" : ""}}]}}}] , "batchId" : "5d0f1c53-92a2-48cb-8c84-1061769962c1"}

This basically means that any queries that operate on fields (with a name different from the peristed name) in the inner list will fail.

---

Affects: 1.7.2 (Fowler SR2)

Referenced from: pull request #384, and commits 593e54f, 8925c73, 116dda6, f7ab448, a875124

Backported to: 1.9.3 (Hopper SR3), 1.8.5 (Gosling SR5)

1 votes, 1 watchers

[spring-projects-issues]

Hansel DOrnellas commented

Troubleshooting this some more, I found that at some point when it parses the expression, it calls getMappedValue(Field documentField, Object value)

Where value is
{ "$and" : [ { "resolution" : { "$ne" : null }} , { "resolution" : { "$ne" : ""}}]}

and documentField is Field with name $elemMatch

it eventually goes to execute:
if (isNestedKeyword(value)) {
return getMappedKeyword(new Keyword((DBObject) value), null);
}

Notice the null in the second parameter--I am wondering if it should have passed the entity.

The reason, because in getMappedKeyword, when evaluating the each condition (which would now be resolution fields), it calls getMappedObject(..), but the entity is now null.
In getMappedObject, it then calls createPropertyField. In this method, when entity is null, it doesn't use the MetadataBackedField; rather it just instantiates a new Field object.

Hence the resolution field is unchanged.

[spring-projects-issues]

Hansel DOrnellas commented

digging deeper still. The BasicMongoPersistentEntity's propertyCache, only contains the top level @Field mappings. It doesn't contain any of the @Field mappings for properties for entities of List. In the example, you'l find for id, status and display, but not for display's resolution.

[spring-projects-issues]

Hansel DOrnellas commented

BTW....I tried the latest release (1.8.4.RELEASE) and it suffers from the same problem.