The A query returns the port and network data from MongoDB Datasource and I want the result of it to be used in the B query. So how can I approach it?
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I'm fairly new to mongodb but I was wondering if there's a way by which we can get 2 different results from same mongodb collection in one database call uisng mongo java driver with morphia.
I have a collection accounts and I'm fetching data based on a key accountId. I need below two results/outputs from this collection in one query.
count of all the documents where accountID is 'xyz'
ResultList of first N documents where accountID is 'xyz' AND resultSet is sorted by a timestamp field.
to resolve the second scenario I'm using:
..Query....limit(N).order("TimeField").field("TimeField").filter("accountID =", "xyz").asList();
This is working fine as per expectation but to get the total count (scenario 1) of all documents with accountId = 'xyz' needs another mongodb call, which I want to avoid.
MongoDB doesn't support such batching on queries, unfortunately. You'll have to execute two separate calls.
I am trying to query out the data from my MongoDB database but there are some fields which I would like to omit as MongoDB will query the whole collections with id, n out.
I did this to limit the query but unfortunately only one field could be omitted but not the other which is the 'n' field. How can I omit two fields?
data = collection.find_one({"files_id": file_id},{"_id":0,"data":1})
And I also realized that my query for data has the field name (u'data') too, how can I query it so that it only returns the data? for this case it's a binary data
Example:
{u'data': Binary('\x00\x00\xed\x00\n\x00\x00\xd5\xa9\x00\x000\x00\x00\x00#\x00\x00\x0f\xff\xf0\x00\x0b\x80\x00\x00\x00
Kindly assist thanks!
I have a mongodb query, and I want to add a computed field. The computed field is based on where or not the item is in the results of another query. So my query returns the columns a,b,c,d, and then column e should be based on whether or not the current row would be matched by another query.
Is there an efficient way to do this in mongo? I'm not really sure how to do this one...
There is no way currently to execute a function as you describe within the database when returning a document via standard functions such as find. It's been requested by the community, but the general request is to operate only on a single document.
There are calculated fields using $project in the aggregation framework. But, they only operate on the current document in the pipeline. So, they can't summarize other queries.
You'll need to likely build your e value as part of your data access layer.
I have 2 collections on 2 separate DBs. Both store an array field. I plan to query both at once so that:
All collection 1 documents that have elements [A,B] in their array
field and their _ids are present in collection 2's array field with a
specific document _id.
As an example:
docs (collection 1, DB 1):
[{"_id":ObjectId("doc1"), "array1":["A","B"]}, {"_id":ObjectId("doc2"), "array1":["A","C"]}]
user_docs (collection 2, DB 2):
[{"_id":ObjectId("usr1"), "array2": [ObjectId("doc1"),ObjectId("foo")]}, {"_id":ObjectId("usr2"), "array2": [ObjectId("bar"),ObjectId("baz")]}]
I need a query that given A,B and usr1, returns the 'doc1' object (because it has A,B in it's array1 field and usr1 has it in it's array2 field).
I obviously can fetch all docs having A,B in one query and all usr1's docs in another query and find the common elements at application level, but is there any better way of doing it using MongoDB?
Thanks for your help.
Ok im not sure i understand exactly what your trying to do from your description. But i dont understand why you would query data across db's this just seems very heavy handed to me why cant you store both the data sets in the same db. You can always separate later if required? Im not sure this will solve your vague problem but it would be a good place to start.
best of Luck.
You will have to query MongoDB twice, since you have no possibility of a join. You will have to do it on application level. If you can denormalize, do it. Cash the needed data in a embedded doc, so that you can do one query only.
I think #Eamonn is right, that you shouldn't have to do a query across DBs.
I need to apply a set of filters (queries) to a collection. By default, the MongoDB applies AND operator to all queries submitted to find function. Instead of whole AND I need to apply each query sequentially (one by one). That is, I need to run the first-query and get a set of documents, run the second-query to result of first-query, and so on.
Is this Possible?
db.list.find({..q1..}).find({..q2..}).find({..q3..});
Instead Of:
db.list.find({..q1..}, {..q2..}, {..q3..});
Why do I need this?
Bcoz, the second-query needs to apply an aggregate function to result of first-query, instead of applying the aggregate to whole collection.
Yes this is possible in MongoDB. You can write nested queries as per the requirement.Even in my application I created nested MongoDb queries.If you are familiar with SQL syntax then compare this with in of sql syntax:
select cname from table where cid in (select .....)
In the same way you can create nested MongoDB queries on different collections also.