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Elasticsearch query Combine 2 queries or Elastic search Join Query

This is my one elastic document example:
"_source": {
"leg_b":{
"team_name" : "aaaa",
"channel_uuid" : "12121"
},
wrapup":[
"0":{
"name": "sss",
"channel_uuid": "12121"
},
"1":{
"name": "bbb",
"channel_uuid" : "21212"
},
"2":{
"name": "acbs",
"channel_uuid" : "111211"
}
]
}
I have to perform search on "leg_b.team_name" value and find out its "channel_uuid" value on the basis of leg_b's "channel_uuid",NEXT I will search in wrapup object for common "channel_uuid" values in the Same Query.
Example,
lets consider above document, First I will search on leg_b.team_name = "aaaa" after that I will take leg_b.channel_uuid = "12121" and search on wrapup object channel_uuid.
Explaination:
So there are two searches are going on 1) leg_b.team_name="aaaa" which returns this document and after that 2) on the returned doc which I got from 1st search, I will take its leg_b.channel_uuid to search on wrapup common channel uuid. (i.e, leg_b channel_uuid is "12121" so I should get "wrapup" channel_uuid : "12121" objects. It exclude "acbc" because its channel_uuid : "111211".
So it should return,
"_source": {
"leg_b":{
"team_name" : "aaaa",
"channel_uuid" : "12121"
},
"wrapup":[
"0":{
"name": "sss",
"channel_uuid": "12121"
},
"1":{
"name": "bbb",
"channel_uuid" : "21212"
}
]
}
Please suggest some approach, Thank you.

How to write mongo cli query in mongo-template for $in aggregation

This is how my data looks like
{
"_id" : "2011250546437843117",
"name" : "Book",
"textbook" : [
"Maths",
"Science"
],
"language" : [
"English"
],
"isRead" : true,
"isAvailable" : true
}
I have to filter documents based on textbook,and based on that isRead field should be true or false.
my mongo query is
db.user.aggregate([
{
$match: {
"isAvailable": true
}
},
{
$project: {
"textbook": 1,
"name": 1,
"isread": {
$in: [
"Maths",
"$textbook"
]
}
}
}
]);
I have tried to write this using mongo-template
Aggregation aggregation = newAggregation(match(Criteria.where("isAvailable").is(true)),
project("textbook","name"));
I dont understand how to write the $in operator in project stage.
Thankyou in advance.

How to query MongoDb subdocuments in Java

Dear MongoDb Experts out there! I am new to Mongo and I am currently working with a MongoDb with Java.
Having a MongoDb with a collection called "teams" with the following example structure:
{[
{
"id": "123",
"name": "Dev1",
"employees": [
{"name": "John", "age": 30},
{"name": "Jane", "age": 30}
]
},
{
"id": "456",
"name": "Dev2",
"employees": [
{"name": "Mike", "age": 30},
{"name": "Oscar", "age": 27}
]
}
]}
I want to have a query which returns an array with all employees, that are 30 years old. So the expected result would be:
{[
{"name": "John", "age": 30},
{"name": "Jane", "age": 30},
{"name": "Mike", "age": 30}
]}
It would be even better to only get the employees name (since I know the age I searched for), like:
{[
{"name": "John"},
{"name": "Jane"},
{"name": "Mike"}
]}
I have a MongoCollection object:
MongoCollection<Document> collection = mongoClient
.getDatabase(databaseName)
.getCollection("teams")
My question: Is it possible to retrieve my expected result from the MongoDb? If so, which operations do I have to call on my collection object?

Approach 1: Find with $elemMatch projection
db.getCollection('teams').find(
{"employees.age":30},
{ "employees": { "$elemMatch": { "age": 30 } },"_id":0 }
)
Output Format:
{
"employees" : [
{
"name" : "John",
"age" : 30.0
}
]
}
{
"employees" : [
{
"name" : "Mike",
"age" : 30.0
}
]
}
Approach 2: Aggregate with $unwind and key renaming using $projection
db.getCollection('teams').aggregate([
{"$match": {"employees.age":30}} ,
{"$unwind": "$employees"},
{"$match": {"employees.age":30}} ,
{"$project": {"name": "$employees.name","_id":0}}
])
Output format:
{
"name" : "John"
}
{
"name" : "Jane"
}
{
"name" : "Mike"
}
Approach 1 would be faster, but require additional work at app layer. It is recommended to offload formatting tasks to app servers rather than on db itself.
Approach 2 can instantly give to the formatted results, doing the querying and formatting both in the database servers

How do I create an ElasticSearch query without knowing what the field is?

I have someone putting JSON objects into Elasticsearch for which I do not know any fields. I would like to search all the fields for a given value using a matchQuery.
I understand that the _all is deprecated, and the copy_to doesn't work because I don't know what fields are available beforehand. Is there a way to accomplish this without knowing what fields to search for beforehand?

Yes, you can achieve this using a custom _all field (which I called my_all) and a dynamic template for your index. Basically, this idea is to have a generic mapping for all fields with a copy_to setting to the my_all field. I've also added store: true for the my_all field but only for the purpose of showing you that it works, in practice you won't need it.
So let's go and create the index:
PUT my_index
{
"mappings": {
"_doc": {
"dynamic_templates": [
{
"all_fields": {
"match": "*",
"mapping": {
"copy_to": "my_all"
}
}
}
],
"properties": {
"my_all": {
"type": "text",
"store": true
}
}
}
}
}
Then index a document:
PUT my_index/_doc/1
{
"test": "the cat drinks milk",
"age": 10,
"alive": true,
"date": "2018-03-21T10:00:00.123Z",
"val": ["data", "data2", "data3"]
}
Finally, we can search using the my_all field and also show its content (because we store its content) in addition to the _source of the document:
GET my_index/_search?q=my_all:cat&_source=true&stored_fields=my_all
And the result is shown below:
{
"_index": "my_index",
"_type": "_doc",
"_id": "1",
"_score": 0.2876821,
"_source": {
"test": "the cat drinks milk",
"age": 10,
"alive": true,
"date": "2018-03-21T10:00:00.123Z",
"val": [
"data",
"data2",
"data3"
]
},
"fields": {
"my_all": [
"the cat drinks milk",
"10",
"true",
"2018-03-21T10:00:00.123Z",
"data",
"data2",
"data3"
]
}
}
So given you can create the index and mapping of your index, you'll be able to search whatever people are sending to it.

MongoDB Java Driver aggregation with regex filter

I am using MongoDB Java Driver 3.6.3.
I want to create regex query with group by aggregation to retrieve distinct values.
Let's say I have json:
[{
"name": "John Snow",
"category": 1
},
{
"name": "Jason Statham",
"category": 2
},
{
"name": "John Lennon",
"category": 2
},
{
"name": "John Snow",
"category": 3
}]
I want to create query where regex is like "John.*" and group it by name so there would be only one "John Snow"
Expected result is:
[{
"name": "John Snow",
"category": 1
},
{
"name": "John Lennon",
"category": 2
}]

The answer provided by felix is correct, in terms of Mongo Shell commands. The equivalent expression of that command using the MongoDB Java driver is:
MongoClient mongoClient = ...;
MongoCollection<Document> collection = mongoClient.getDatabase("...").getCollection("...");
AggregateIterable<Document> documents = collection.aggregate(Arrays.asList(
// Java equivalent of the $match stage
Aggregates.match(Filters.regex("name", "John")),
// Java equivalent of the $group stage
Aggregates.group("$name", Accumulators.first("category", "$category"))
));
for (Document document : documents) {
System.out.println(document.toJson());
}
The above code will print out:
{ "_id" : "John Lennon", "category" : 2 }
{ "_id" : "John Snow", "category" : 1 }

You can achieve this with a $regex in $match stage, followed by a $group stage:
db.collection.aggregate([{
"$match": {
"name": {
"$regex": "john",
"$options": "i"
}
}
}, {
"$group": {
"_id": "$name",
"category": {
"$first": "$category"
}
}
}])
output:
[
{
"_id": "John Lennon",
"category": 2
},
{
"_id": "John Snow",
"category": 1
}
]
you can try it here: mongoplayground.net/p/evw6DP_574r

You can use Spring Data Mongo
like this
Aggregation agg = Aggregation.newAggregation(
ggregation.match(ctr.orOperator(Criteria.where("name").regex("john", "i")),
Aggregation.group("name", "category")
);
AggregationResults<CatalogNoArray> aggResults = mongoTemp.aggregate(agg, "demo",demo.class);