I have a collection like.
{
"id" : 101,
"name" : "ragav",
"address" : "143 karnadaka",
"products" : [
{
"id" : 2,
"name" : "AA",
"amount" : "150"
},
{
"id" : 4,
"name" : "BB",
"amount" : "15"
},
{
"id" : 6,
"name" : "CC",
"amount" : "210"
},
]
}
I need to find a record in this collection based on product. I running the following query.
Query
db.Response.find(
{"products.id":2},
{"products.id.$":1,"id":1,"name":1,"address":1}
)
In my mongo terminal i got the output. But i accessing through python using pymongo2.8 when i taring to iterate pymongo object getting an error like this.
database error: Executor error: InternalError: ambiguous positional
projection
what is the reason for this error? How it solve??
If a positional operator appears in a projection or update, and there were multiple array matches against the document, MongoDB will issue an error.
so basically the issue is with the $ in the products.id.$
and this is an expected behavior. please refer https://jira.mongodb.org/browse/SERVER-14662 for more info and examples.
Related
BED_MAST this is my one collection bed_mast contains WARD_ID and want to perform join to my other collection with is WARD_MAST given below.
{
"_id" : ObjectId("5e53c95a26b0e5ad0fb46376"),
"Bed_id" : "bd-10",
"WARD_ID" : "4",
"OCCUPIED" : "0",
"BED_TYPE" : "single AC"
}
{
"_id" : ObjectId("5e53c95a26b0e5ad0fb46377"),
"Bed_id" : "bd-11",
"WARD_ID" : "1",
"OCCUPIED" : "0",
"BED_TYPE" : "single Non AC"
}
WARD_MAST this is my WARD_MAST having ward_id. but while I am putting lookup I am not getting any data.
{
"_id" : ObjectId("5e53c95b26b0e5ad0fb46544"),
"patient_id" : null,
"ward_id" : 1,
"total_beds" : 55,
"ward_name" : "Ward 1"
}
{
"_id" : ObjectId("5e53c95d26b0e5ad0fb46545"),
"patient_id" : null,
"ward_id" : 2,
"total_beds" : 63,
"ward_name" : "Ward 2"
}
MY query is
db.BED_MAST.aggregate([{$lookup:{'from':"WARD_MAST",'localField':"WARD_ID",'foreignField':"ward_id",'as':"lookup_value"}}]).pretty()
output: I have confirmed the data by running this query to MySQL there it is working fine
{
"_id" : ObjectId("5e53c95b26b0e5ad0fb46388"),
"Bed_id" : "bd-28",
"WARD_ID" : "6",
"OCCUPIED" : "0",
"BED_TYPE" : "NICU",
"lookup_value" : [ ]
}
SAMPLE VALUES DATA IS GIVEN ALL DATA IS NOT POSSIBLE TO GIVE. I know it was asked 1000 times but not able to resolve this question. tried to solve with lookup. but it showing blank space. Is anything I am missing.
The problem is BED_MAST collection's WARD_ID has string values and WARD_MAST collection's ward_id has Number values.
This question already has answers here:
Updating a Nested Array with MongoDB
(2 answers)
Closed 5 years ago.
Following is a MongoDB document:
{
"_id" : 2,
"mem_id" : M002,
"email" : "xyz#gmail.com",
"event_type" : [
{
"name" : "MT",
"count" : 1,
"language" : [
{
"name" : "English",
"count" : 1,
"genre" : [
{
"name" : "Action",
"count" : 6
},
{
"name" : "Sci-Fi",
"count" : 3
}
],
"cast" : [
{
"name" : "Sam Wortington",
"count" : 2
},
{
"name" : "Bruce Willis",
"count" : 4
},
{
"name" : "Will Smith",
"count" : 7
},
{
"name" : "Irfan Khan",
"count" : 1
}
]
}
]
}
]
}
I'm not able to update fields that is of type array, specially event_type, language, genre and cast because of nesting. Basically, I wanted to update all the four mentioned fields along with count field for each and subdocuments. The update statement should insert a value to the tree if the value is new else should increment the count for that value.
What can be the query in mongo shell?
Thanks
You are directly hitting one of the current limitations of MongoDB.
The problem is that the engine does not support several positional operators.
See this Multiple use of the positional `$` operator to update nested arrays
There is an open ticket for this: https://jira.mongodb.org/browse/SERVER-831 (mentioned also there)
You can also read this one on how to change your data model: Updating nested arrays in mongodb
If it is feasible for you, you can do:
db.collection.update({_id:2,"event_type.name":'MT' ,"event_type.language.name":'English'},{$set:{"event_type.0.language.$.count":<number>}})
db.collection.update({_id:2,"event_type.name":'MT' ,"event_type.language.name":'English'},{$set:{"event_type.$.language.0.count":<number>}})
But you cannot do:
db.collection.update({_id:2,"event_type.name":'MT' ,"event_type.language.name":'English'},{$set:{"event_type.$.language.$.count":<number>}})
Let's take case by case:
To update the field name in event_type array:
db.testnested.update({"event_type.name" : "MT"}, {$set : {"event_type.name" : "GMT"}})
This command will update the name for an object inside the event_type list, to GMT from MT:
BEFORE:
db.testnested.find({}, {"event_type.name" : 1})
{ "_id" : 2, "event_type" : [ { "name" : "MT" } ] }
AFTER:
db.testnested.find({}, {"event_type.name" : 1})
{ "_id" : 2, "event_type" : [ { "name" : "GMT" } ] }
2.To update fields inside event_type, such as language, genre that are intern list:
There is no direct query for this. You need to read the document, update that document using the JavaScript or language of your choice, and then save() the same. I dont think there is any other way available till mongo 2.4
For further documentation, you can refer to save().
Thanks!
I use mongoDB (version 3.0.2) for my application and if I will search for a User named "Hannes" than I get the following error above.
db.User.find() works without any problems.
Does anyone know what the problem is?
Thanks a lot!
db.User.find({$text:{$search:'Hannes'}})
Error: error: {
"$err" : "Unable to execute query: error processing query: ns=apoSoftDatabase.User limit=0 skip=0\nTree: TEXT : query=Hannes, language=, tag=NULL\nSort: {}\nProj: {}\n planner returned error: need exactly one text index for $text query",
"code" : 17007
}
[EDIT]
This is my document structure:
db.User.insert({ "_id" : ObjectId("5589929b887dc1fdb501cdbf"), "_class" : "com.smartinnotec.aposoft.dao.domain.User", "title" : "", "firstname" : "Claudia", "surname" : "Amreiter", "birthdate" : ISODate("1989-06-02T03:43:43.124Z"), "sex" : "FEMALE", "telephone" : "0664 / 342233223", "email" : "claudia.amreiter#aon.de", "username" : "claudia", "password" : "claudiapw", "address" : { "_id" : null, "street" : "strasse 21a", "postalCode" : 58441, "region" : "village", "country" : "Germany" }})
The "error" is because uou don't have a "text" index on your collection and you need one to use the $text operator in queries.
Create a text index
Your document may have fields like:
{
"a": "sam",
"b": "wise"
}
You can then create a "text index" over all or just a single field with something like:
db.collection.createIndex({ "a": "text", "b": "text" })
Then you can query with:
db.collection.find({ "$text": { "$search": "sam wise" } })
Or any other valid combination without problem.
I don't know the field name of your collection, however you can try this:
Try db.User.find({[field name]:'Hannes'})
When I issue the following query:
db.users.find({"pic.status" : {$ne : null} }, {"pic" : 1}).toArray()
I expect to receive all users whose pic.status is NOT null. However, the actual result looks something like this:
{
"_id" : ObjectId("4f1e1ab9cdf9dbaa160000bf"),
"pic" : {
"id" : "4f1e1ab9cdf9dbaa160000be",
"status" : null
}
},
{
"_id" : ObjectId("4f1e28480eaf38193d00006f"),
"pic" : {
"id" : "4f1e28480eaf38193d00006e",
"status" : null
}
}
That is, I receive users whose pic.status IS null. How can I fix this?
I know it's an old question, and might not be relevant anymore, but as there was no accepted answer, I thought I'll comment for anyone looking for answer.
I was able to reproduce the problem on MongoDB version 2.4.9.
> db.sourceListings.findOne({displayed:{$ne:null}});
{
<.. other stuff went here..>
"displayed" : null
}
The problem disappears on Version 2.6.1:
> db.sourceListings.findOne();
{
<.. other stuff ..>
"displayed" : null
}
> db.sourceListings.findOne({displayed:{$ne:null}});
null
Probably was fixed somewhere in between these two versions.
I cannot seem to reproduce this. What version of Mongo are you using? (I am using 2.1.1-pre) Here are the steps that I took. The following is from the JS shell:
> db.users.save({
"_id" : 1,
"pic" : {
"id" : "4f1e1ab9cdf9dbaa160000be",
"status" : null
}
});
> db.users.save({
"_id" : 2,
"pic" : {
"id" : "4f1e28480eaf38193d00006e",
"status" : null
}
});
> db.users.save({
"_id" : 3,
"pic" : {
"id" : "4f1e28480eaf38193d00006e",
"status" : "Something"
}
});
> db.users.find({"pic.status":{$ne:null}}, {pic:1}).toArray()
[
{
"_id" : 3,
"pic" : {
"id" : "4f1e28480eaf38193d00006e",
"status" : "Something"
}
}
]
Only the document containing "pic.status":"Something" is returned.
My only thought is, are you absolutely certain that the value of (null) in the query is the same as what is saved in the documents? Were the documents saved using the JS shell, or were they saved using a driver in a different language? Theoretically, null, should be null, should be null, in any language, but I know that different languages represent "no value" differently. In python, for example, the value for "no value" is (None). (null) is not recognised in python.
In a python shell, I attempted to save a document with (null) as a value, but received an error:
In [13]: coll.save({"_id":5, "pic":{"id":5, "status":null}})
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
/Users/mbastien/mongodb-osx-x86_64-2.0.1/bin/<ipython-input-13-1ad232456c88> in <module>()
----> 1 coll.save({"_id":5, "pic":{"id":5, "status":null}})
NameError: name 'null' is not defined
I then inserted (with the Python shell) a status of 'null' ('null' being a string)
In [15]: coll.save({"_id":5, "pic":{"id":5, "status":'null'}})
Out[15]: 5
Not surprisingly, when I reran the query in the JS shell, this document was returned, because 'null' != null
> db.users.find({"pic.status":{$ne:null}}, {pic:1}).toArray()
[
{
"_id" : 3,
"pic" : {
"id" : "4f1e28480eaf38193d00006e",
"status" : "Something"
}
},
{
"_id" : 5,
"pic" : {
"status" : "null",
"id" : 5
}
}
]
Is this similar to what you are experiencing, or can you reproduce this 100% in the JS shell? Hopefully, we will be able to get to the root of this issue!
Use $nin with a single element in the array. It'll behave as you expect. KI with many of the people who use mongo.
My collection (MongoDB v 2.0.2) has following records:
db.organization.find({})
{ "_id" : 1001, "path" : [ ], "parent" : null }
{ "_id" : 1002, "path" : [ 1001 ], "parent" : NumberLong(1001) }
organization has indexes:
db.organization.ensureIndex({"path":1});
db.organization.ensureIndex({"parent":1},{sparse:false});
(note I put awarnes sparse : false - to grant that null is indexed)
But, executing:
db.organization.find({"parent":null})
Returns empty set. What is wrong? Thank you in advance
I had the same issue. After reading the following documents
querying and nulls
BSON specification
I tried to query for the different BSON element types and found that my null was represented as a BSON element type 6 (undefined, deprecated) instead of the expected BSON element type 10 (null).
db.collection.find({ field: { "$type" : 6} };
Just checked following script at 2.0 and 2.0.2:
db.items.insert({ "_id" : 1001, "path" : [ ], "parent" : null })
db.items.insert({ "_id" : 1002, "path" : [ 1001 ], "parent" : NumberLong(1001) })
db.items.ensureIndex({"path":1});
db.items.ensureIndex({"parent":1},{sparse:false});
db.items.find({"parent":null})
actually returns one document that you expect:
{ "_id" : 1001,
"path" : [],
"parent" : null }
Also you can look into this doc about querying and nulls, probably should help you avoid possible future mistakes.