I have three collections how can i create a model such that if i want to find a auto_mobile_reference_no of a user with adjustor id: "ABA123" how can i do that?
//Company collection
{
"company_id" : "NUV123",
"company_name" : "ABC",
}
//Adjustor collection
{
"admin" : true,
"claim_adjustor_id" : "ABA123",
"company_id" : "NUV123",
"adjustor_username" : "test",
"adjustor_password" : "test"
},
{
"admin" : true,
"claim_adjustor_id" : "XYQ324",
"company_id" : "NUV123",
"adjustor_username" : "test1",
"adjustor_password" : "test22"
}
//Image collection
{
"claim_adjustor_id" : "ABA123",
"automobile_reference_no" : "1LNHM83W13Y609413",
"date_last_predicted" : "03/12/2019"
}
MongoDB is not designed to do efficient joins across collections. You should look at merging your data (based on access pattern) into a single collections.
If your collections are unsharded, you can however you aggregation framework. You can use combination of $match and $lookup stages to query a foreign collection and join the data with the other. As of version 4.0, $lookup doesn't support sharded collections. So it might not work for you if your dataset is huge.
You can read more here
Related
I am new to the mongodb. I have one mongo database which contains the around 150 collections. Currently I want to create the master document for each collection. Master document will contain all the fields in that collection. e.g. Lets say I have a users collection and it contains the two records as
{
"_id" : ObjectId("59e5e384cbead107344e6420"),
"user_name" : "test",
"pass" : "system",
"email": "em#gm.com"
}
{
"_id" : ObjectId("59e5e384cbead107344e6420"),
"user_name" : "test1",
"org":{
"name":"My Org"
},
"pass" : "test"
}
After merging the two documents I will get the master record as
{
"_id" : ObjectId("59e5e384cbead107344e6420"),
"user_name" : "test",
"email" : "em#gm.com",
"org":{
"name":"My Org"
},
"pass" : "test"
}
Here I am not worried about the data. I need the structure of the document and data types of the fields. I have thousands of the records which are not managed properly. I need a master template which will contain the all the possible fields in all the documents of one collection. I have to create such template for each collection.
Appreciating your help.
I am trying to find a way to filter the records in Mongo db using Spring query.
Here is the scenario, let's see I have an Activity entity/document. One of the fields is a list of names. I want to see if I can get all the records that the names field includes get given value, let's say "Joker".
For example, my json in Mongo is
Activity 1 -
{
"_id" : ObjectId("52c14eb92f7ceb854e445354"),
...
"names" : [{
"username" : "username1",
"realname" : "Super Man"
}, {
"username" : "username2",
"realname" : "Iron Man"
}]
}
Activity 2 -
{
"_id" : ObjectId("52c14eb92f7ceb854e445355"),
...
"names" : [{
"username" : "username3",
"realname" : "Bat Man"
}, {
"username" : "username4",
"realname" : "Joker"
}]
}
And I expect the query will let me get Activity 2 only.
Also, if possible, I prefer to use spring Mongo query in my code. Thanks in advance.
Try
db.collection.find({"names.realname": "Joker"});
I never used Spring query but should be something like
Query query = new Query();
query.addCriteria(Criteria.where("names.realname").is("Joker"));
List<MyClass> users = mongoTemplate.find(query, MyClass.class);
Not a question about joins in mongoDB
I have two collections in mongoDB, which do not have a common field and which I would like to apply a zip function to (like in Python, Haskell). Both collections have the same number of documents.
For example:
Let's say one collection (Users) is for users, and the other (Codes) is of unique randomly generated codes.
Collection Users:
{ "_id" : ObjectId(""), "userId" : "123"}
{ "_id" : ObjectId(""), "userId" : "456"}
Collection Codes:
{ "_id" : ObjectId(""), "code" : "randomCode1"}
{ "_id" : ObjectId(""), "code" : "randomCode2"}
The desired output would to assign a user to a unique code. As follows:
Output
{ "_id" : ObjectId(""), "code" : "randomCode1", "userId" : "123"}
{ "_id" : ObjectId(""), "code" : "randomCode2", "userId" : "456"}
Is there any way of doing this with the aggregation pipeline?
Or perhaps with map reduce? Don't think so because it only works on one collection.
I've considered inserting another random id into both collections for each document pair, and then using $lookup with this new id, but this seems like an overkill. Also the alternative would be to export and use Python, since there aren't so many documents, but again I feel like there should be a better way.
I would do something like this to get the records from collection 1 & 2 and merge the required fields into single object.
You have already confirmed that number of records in collection 1 and 2 are same.
The below code will loop through the cursor and map the required fields into one object. Finally, you can print the object to console or insert into another new collection (commented the insert).
var usersCursor = db.users.find( { } );
var codesCursor = db.codes.find( { } );
while (usersCursor.hasNext() && codesCursor.hasNext()) {
var user = usersCursor.next();
var code = codesCursor.next();
var outputObj = {};
outputObj ["_id"] = new ObjectId();
outputObj ["userId"] = user["userId"];
outputObj ["code"] = code["code"];
printjson( outputObj);
//db.collectionName.insertOne(outputObj);
}
Output:-
{
"_id" : ObjectId("58348512ba41f1f22e600c74"),
"userId" : "123",
"code" : "randomCode1"
}
{
"_id" : ObjectId("58348512ba41f1f22e600c75"),
"userId" : "456",
"code" : "randomCode2"
}
Unlike relational database in MongoDB you doing JOIN stuff at the app level (so it will be easy to horizontal scale the database). You need to do that in the app level.
we have a collection say TestColl
having document like
{
"_id" : ObjectId("57558a793f50f61400af205c"),
"title" : "Tile 1",
"addSites" : true,
"version" : 11,
"isMajorVersion" : true
},
{
"_id" : ObjectId("654558a793f50f61400af205c"),
"title" : "Title 2,
"addSites" : false,
"version" : 11,
"isMajorVersion" : true
}
for every documemt of TestColl there is a separete collection in DB
so we have another two collections which is created based upon the object Id of TestColl which is
57558a793f50f61400af205c and 654558a793f50f61400af205c
this makes total three collections.
looking for a way to access a collection '57558a793f50f61400af205c' if my query returns document having _id=654558a793f50f61400af205c in a single query.
Constraint : we need only query without creating any stored procedure or function just pure mongodb query
you can use forEach loop and access data from collection like this:
db.kt.find().forEach(function(doc){
var colName = doc._id.str;
var data = db.getCollection(colName).find().toArray();
printjson(data);
print(","); // to have array of arrays [[],[],[]]
})
I want to aggregate a model tree structure directly in mongodb database with Aggregations.
Is it possible to do hierarchical aggregations like that ? Currently, I do that in a program.
I want to use a collection like :
{
"Name" : "john",
"Parents" : ["sandy", "bryan"]
}
{
"Name" : "sandy",
"Parents" : ["bill", "daisy"]
}
{
"Name" : "bryan",
"Parents" : ["dora", "david"]
}
{
"Name" : "dora",
"Parents" : ["cliff", "darla"]
}
And generate a new collection like :
{
"Name" : "sandy",
"Parents" : ["bill", "daisy"],
"Ancestrors" : ["bill", "daisy"]
}
{
"Name" : "dora",
"Parents" : ["cliff", "darla"],
"Ancestrors" : ["cliff", "darla"]
}
{
"Name" : "bryan",
"Parents" : ["dora", "david"],
"Ancestrors" : ["dora", "david", "cliff", "darla"]
}
{
"Name" : "john",
"Parents" : ["sandy", "bryan"],
"Ancestrors" : ["sandy", "bryan", "bill", "daisy", "dora", "david", "cliff", "darla"]
}
I don't think that use a MapReduce to do a tree structure aggregation is possible since MongoDb 2.4 because we can't use "db.mycollection.find(...)" in map functions.
So we can't retrieve hierarchicals documents in map functions...
In MongoDB 2.4, map-reduce operations, the group command, and $where operator expressions cannot access certain global functions or
properties, such as db, that are available in the mongo shell.
When upgrading to MongoDB 2.4, you will need to refactor your code if
your map-reduce operations, group commands, or $where operator
expressions include any global shell functions or properties that are
no longer available, such as db.