java - I need to retrieve MongoDB's object just with filtered's array item

Question

I'm needing to retrieve just with two dates, all the documents from my MongoDB's collection, with the filtered items from the array.

This is an example of 2 of my documents;

{
        "_id" : ObjectId("5f18fa823406b7000132d097"),
        "last_date" : "22/07/2020 23:48:32",
        "history_dates" : [
                "22/07/2020 23:48:32",
                "22/07/2020 00:18:53",
                "23/07/2020 00:49:12",
                "23/07/2020 01:19:30"
        ],
        "hostname" : "MyHostname1",
        "ip" : "142.0.111.79",
        "component" : "C:\Windows\System32\es-ES\KernelBase.dll.mui",
        "process" : "LogonUI.exe",
        "date" : "23/07/2020 10:26:04",
}
{
        "_id" : ObjectId("5f18fa823406b7000132d098"),
        "last_date" : "22/07/2020 23:48:33",
        "history_dates" : [
                "22/07/2020 23:48:33",
                "23/07/2020 00:18:53",
        ],
        "hostname" : "MyHostName2",
        "ip" : "142.0.111.54",
        "component" : "C:\Windows\System32\es-ES\KernelBase.dll.mui",
        "process" : "svchost.exe",
        "date" : "23/07/2020 10:26:04",
}

I'm needing to make a find to my database (Using Spring Data), to retrieve the same objects, but with the "history_dates"'s array filtered between the 2 dates recieved.

For example, if my 2 recieved dates are: "23/07/2020" and "24/07/2020", I want MongoDB to return the next objects;

{
        "_id" : ObjectId("5f18fa823406b7000132d097"),
        "last_date" : "22/07/2020 23:48:32",
        "history_dates" : [
                "23/07/2020 00:49:12",
                "23/07/2020 01:19:30"
        ],
        "hostname" : "MyHostname1",
        "ip" : "142.0.111.79",
        "component" : "C:\Windows\System32\es-ES\KernelBase.dll.mui",
        "process" : "LogonUI.exe",
        "date" : "23/07/2020 10:26:04",
}
{
        "_id" : ObjectId("5f18fa823406b7000132d098"),
        "last_date" : "22/07/2020 23:48:33",
        "history_dates" : [
                "23/07/2020 00:18:53"
        ],
        "hostname" : "MyHostName2",
        "ip" : "142.0.111.54",
        "component" : "C:\Windows\System32\es-ES\KernelBase.dll.mui",
        "process" : "svchost.exe",
        "date" : "23/07/2020 10:26:04",
}

I'm really ignorant about MongoDB's queries, and I have been trying to make this with Spring Data all the week.

UPDATE 1.

Thanks varman, and do you know how can i just retrieve the documents with filtered arrays not empty?

Answer 1

So basically you need to do filter. MongoTemplate offers a lot of operation for mongodb, if some methods don't exist in MongoTemplate, we can go with Bson Document pattern. In that case, try this article: Trick to covert mongo shell query.

Actually you need a Mongo query something like following. Using $addFields one of the methods shown below. But you can use $project, $set etc. Here $addFields overwrites your history_dates. (It uses to add new fields to document too).

{
    $addFields: {
        history_dates: {
            $filter: {
                input: "$history_dates",
                cond: {
                    $and: [{
                            $gt: ["$$this", "23/07/2020"]
                        },
                        {
                            $lt: ["$$this", "24/07/2020"]
                        }
                    ]
                }
            }
        }
    }
}

Working Mongo playground.

You need to convert this into spring data. So @Autowired the MongoTemplate in you class.

 @Autowired
    MongoTemplate mongoTemplate;

The method is,

public List<Object> filterDates(){

    Aggregation aggregation = Aggregation.newAggregation(
        a->new Document("$addFields",
            new Document("history_dates",
                new Document("$filter",
                    new Document("input","$history_dates")
                    .append("cond",
                        new Document("$and",
                            Arrays.asList(
                                new Document("$gt",Arrays.asList("$$this","23/07/2020")),
                                new Document("$lt",Arrays.asList("$$this","24/07/2020"))                            
                            )
                        )
                    )
                )
            )       
        )
    ).withOptions(AggregationOptions.builder().allowDiskUse(Boolean.TRUE).build());
    return mongoTemplate.aggregate(aggregation, mongoTemplate.getCollectionName(YOUR_CLASS.class), Object.class).getMappedResults();
}

Mongo template doesn't provide add methods for $addFields and $filter. So we just go with bson document pattern. I haven't tested this in Spring.