Concatenate mongo db fields while aggregating java

Question

I have a collection having following documents -

    {"_id":ObjectId("xxx"),"article_Id":"1","publish_Time":NumberLong(10)}  
    {"_id":ObjectId("yyy"),"article_Id":"1","publish_Time":NumberLong(11)}  
    {"_id":ObjectId("zzz"),"article_Id":"1","publish_Time":NumberLong(12)}

I want to aggregate on article_id and desired result is somewhat like -

  {"_id":{"articleId":"1"}, pub_t:[publish_Time":NumberLong(10),publish_Time":NumberLong(11),publish_Time":NumberLong(10)]}

I want to combine the publish_time field in separate documents to one array in resultant. How can I do this? Thanks in Advance.

Were you able to use the query I provided in my answer?

Dmytro Shevchenko
– Dmytro Shevchenko

2015-12-16 10:38:32 +00:00
Commented Dec 16, 2015 at 10:38 — Dmytro Shevchenko
– Dmytro Shevchenko, Commented Dec 16, 2015 at 10:38
I used $addToSet. It worked fine for me.

Vibhav Singh Rohilla
– Vibhav Singh Rohilla

2016-01-19 05:29:35 +00:00
Commented Jan 19, 2016 at 5:29 — Vibhav Singh Rohilla
– Vibhav Singh Rohilla, Commented Jan 19, 2016 at 5:29

Dmytro Shevchenko · Accepted Answer · 2015-12-15 11:16:11Z

1

Query

db.articles.aggregate(
{
    $group:
    {
        _id:
        {
            articleId: "$article_Id"
        },
        pub_t:
        {
            $push: "$publish_Time"
        }
    }
})

Result

{
    "_id" : {
        "articleId" : "1"
    },
    "pub_t" : [
        NumberLong(10),
        NumberLong(11),
        NumberLong(12)
    ]
}

answered Dec 15, 2015 at 11:16

Dmytro Shevchenko

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