CODEWITHSUNDEEP
mongodbspring-mongodb
Evgeny Kuznetsov
Evgeny Kuznetsov

Reputation: 21

Get likes count and whether user is liked record from MongoDB

I am trying to get count of likes and if user is liked this post in Mongo. I managed to get this via native query with facets, but problems is how can i map this two fields on my custom java class (LikeStatus.class)?

thanks in advance!

please code below:

POJO:

public class LikeStatus {

    String entityId;
    LikedEntityType entityType;
    long likesCount;
    boolean isLikedByUser;

}

Document class:

public class Like {

    @Id
    private String id;
    @EqualsAndHashCode.Include
    private String entityId;
    @EqualsAndHashCode.Include
    private String profileId;
    @EqualsAndHashCode.Include
    private LikedEntityType entityType;
    private LocalDateTime createdAt = LocalDateTime.now();

}

Query i used in Mongo:

> db.likes.aggregate({$facet:
    {count:[
    {$match:{entityId:"entityId"}, 
       $match:{entityType:"OFFER"}}, {$count:"count"}], 
          isliked:[{$match:{profileId:"profileId4"}}, {$count:"isliked"}]}}).pretty();

and gives me result:

{
    "count" : [
        {
            "count" : 3
        }
    ],
    "isliked" : [
        {
            "isliked" : 1
        }
    ]
}

Upvotes: 0

Views: 116

Answers (1)

Evgeny Kuznetsov
Evgeny Kuznetsov

Reputation: 21

I managed to find solution which is suited my needs, hope it will be useful who faced with the same kind of queries in Mongodb and it will give some idea how it can be solved)

Java solution: i used Facet object to collect two aggregation request in one query like this:

In repository layer i created query:

default Aggregation getLikeStatus(String entityId, String entityType, String profileId){
    FacetOperation facet = Aggregation.facet(match(where(ENTITY_ID_FIELD).is(entityId).and(ENTITY_TYPE_FIELD).is(entityType)),
                    Aggregation.count().as(LIKES_COUNT_FIELD)).as(LIKES_COUNT_FIELD)
            .and(match(where(ENTITY_ID_FIELD).is(entityId)
                            .and(ENTITY_TYPE_FIELD).is(entityType)
                            .and(PROFILE_ID_FIELD).is(profileId)),
                    Aggregation.count().as(IS_LIKED_BY_USER_FIELD)).as(IS_LIKED_BY_USER_FIELD);

    ProjectionOperation project = project()
            .and(ConditionalOperators.ifNull(ArrayOperators.ArrayElemAt.arrayOf(LIKES_COUNT_FIELD).elementAt(0)).then(0)).as(LIKES_COUNT_FIELD)
            .and(ConditionalOperators.ifNull(ArrayOperators.ArrayElemAt.arrayOf(IS_LIKED_BY_USER_FIELD).elementAt(0)).then(0)).as(IS_LIKED_BY_USER_FIELD)
            .andExclude("_id");
    return newAggregation(facet, project);
}

then in service layer it returns Document object which is mapped on my custom class LikeStatus fields:

Document status = template.aggregate(likeRepo.getLikeStatus(entityId, entityType, profileId), Like.class, Document.class).getUniqueMappedResult();

my custom POJO:

@Data
@NoArgsConstructor
@AllArgsConstructor
public class LikeStatus {

    String entityId;
    LikedEntityType entityType;
    long likesCount;
    boolean isLikedByUser;

}

Also i post native query solution in Mongo for reference:

    db.likes.aggregate([
{$facet:
   {"likesCountGroup":[
      {$match:{entityId:"entityId", entityType:"TYPE"}},{$count:"likesCount"}
                      ],
    "isUserLikedGroup":[
      {$match:{entityId:"entityId", entityType:"TYPE", profileId:"604cd12c-1633-4661-a773-792a6ec22187"}},
    {$count:"isUserLiked"}
                       ]}},
   {$addFields:{}},
   {$project:{"likes":{"$ifNull":[
             {$arrayElemAt:["$likesCountGroup.likesCount", 0]},0]},
             "isUser":{"$ifNull:[{$arrayElemAt["$isUserLikedGroup.isUserLiked",0]},0]}}}]);

Upvotes: 1

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