I have a document like that:
'subject' : {
'name' :"...."
'facebookPosts':[
{
date:"14/02/2017 20:20:03" , // it is a string
text:"facebook post text here",
other stuff here
}
]
}
and I want to count the facebookPosts within a specific objects that their date field contains e.g "23/07/2016".
Now, I do that by extracting all the documents and count in the client side (spring ) , But I think that's not efficient.
You need to aggregate your results.
final Aggregation aggregation = Aggregation.newAggregation(
Aggregation.match(Criteria.where("facebookPosts.date").regex(REGEX)),
Aggregation.unwind("facebookPosts"),
Aggregation.group().count().as("count"));
Regex might not be the best solution, just an example.
unwind will split array into separate elements you can then count.
Create a class that will hold the count, something like:
public class PostCount {
private Long count;
// getters, setters
}
And then execute it like this:
AggregationResults<PostCount> postCount = mongoTemplate.aggregate(aggregation, Subject.class, PostCount.class);
long count = postCount.getMappedResults().get(0).getCount();
