Say we have the following collection of documents:
{ "_id" : ObjectId("50a69fa904c8310609600be3"), "id" : 100, "city" : "San Francisco", "friends" : [ { "id" : 1, "name" : "John" }, { "id" : 2, "name" : "Betty" }, { "id" : 3, "name" : "Harry" } ] }
{ "_id" : ObjectId("50a69fc104c8310609600be4"), "id" : 200, "city" : "Palo Alto", "friends" : [ { "id" : 1, "name" : "Carol" }, { "id" : 2, "name" : "Frank" }, { "id" : 3, "name" : "Norman" } ] }
{ "_id" : ObjectId("50a69fc304c8310609600be5"), "id" : 300, "city" : "Los Angeles", "friends" : [ { "id" : 1, "name" : "Fred" }, { "id" : 2, "name" : "Neal" }, { "id" : 3, "name" : "David" } ] }
.
.
.
Now let's say that Frank (Palo Alto, id=2) is no longer my friend, and I want to delete him from the collection. I thought the following might work, but it doesn't:
db.test.update({"city":"Palo Alto"},{"$pull":{"friends.name":"Frank"}})
I'd like to be able to do something like that. Delete an object within an array within a collection of documents. How do you do this?
You were close. The query should be like this:
db.test.update({"city":"Palo Alto"},{"$pull":{"friends":{"name":"Frank"}}});
$pull takes an object whose field specifies the field array "friends". The value {"name":"Frank"} represents the query (to run inside the array) to find the element to pull out.
Related
I need to execute the following query:
db.S12_RU.find({"venue.raw":a,"title":/b|c|d|e/}).sort({"year":-1}).skip(X).limit(Y);
where X and Y are numbers.
The number of documents in my collection is:
208915369
Currently, this sort of query takes about 6 minutes to execute.
I have the following indexes:
[
{
"v" : 2,
"key" : {
"_id" : 1
},
"name" : "_id_"
},
{
"v" : 2,
"key" : {
"venue.raw" : 1
},
"name" : "venue.raw_1"
},
{
"v" : 2,
"key" : {
"venue.raw" : 1,
"title" : 1,
"year" : -1
},
"name" : "venue.raw_1_title_1_year_-1"
}
]
A standard document looks like this:
{ "_id" : ObjectId("5fc25fc091e3146fb10484af"), "id" : "1967181478", "title" : "Quality of Life of Swedish Women with Fibromyalgia Syndrome, Rheumatoid Arthritis or Systemic Lupus Erythematosus", "authors" : [ { "name" : "Carol S. Burckhardt", "id" : "2052326732" }, { "name" : "Birgitha Archenholtz", "id" : "2800742121" }, { "name" : "Kaisa Mannerkorpi", "id" : "240289002" }, { "name" : "Anders Bjelle", "id" : "2419758571" } ], "venue" : { "raw" : "Journal of Musculoskeletal Pain", "id" : "49327845" }, "year" : 1993, "n_citation" : 31, "page_start" : "199", "page_end" : "207", "doc_type" : "Journal", "publisher" : "Taylor & Francis", "volume" : "1", "issue" : "", "doi" : "10.1300/J094v01n03_20" }
Is there any way to make this query execute in a few seconds?
I have employee json as below in db, I want to create a map of "addressId"(key) and "city"(value) and return the result.
{
"_id" :1,
"_class" : "com.entity.Employee",
"clientId" : 1,
"addresses" : [
{
"addressId" : 1,
"street" : "ghi",
"city" : "Hyderabad"
},
{
"addressId" : 2,
"street" : "abc",
"city" : "Bangalore"
},
{
"addressId" : 3,
"street" : "def",
"city" : "Chennai"
}
]
}
Please suggest me which operator can I use and whether this can be achieved using $project.
Yes you have to use projection with unwind and forEach to make key value pair
try below mongo query
db.collection_name.aggregate([{"$unwind":"$addresses"},{"$project": {"addressId": "$addresses.addressId", "city":"$addresses.city", "_class":"$_class","clientId":"$clientId"} }]).forEach(function(ojb){ojb[ojb.addressId]=ojb.city; printjson(ojb);});
I have 2 collections structured as below. I have tried $lookup to get the result but I am not getting any result because of my local and foreign fields are in array of object.
Below is my structure:
{
"_id" : ObjectId("5795a3531d3f3afc19caefef"),
"name" : "category1",
"updatedAt" : "1469431592786",
"resources" : [
{
"_id" : ObjectId("5791be003fa3bedc15d3adde"),
"title" : "resource1",
"availability" : false
},
{
"_id" : ObjectId("5795a3771d3f3afc19caeff0"),
"title" : "resource2",
"availability" : true
}
]
}
Above "categories" schema have resources array of object. this resource _id is stored in bookings collection in following way:
"booking":
{
"_id" : ObjectId("57960aa8000ca7a46b7ef683"),
"name" : "1469491200000",
"__v" : 0,
"schedule" : [
{
"resourceId" : ObjectId("5791be003fa3bedc15d3adde"),
"userId" : ObjectId("5791be003fa3bedc15d3adcve"),
"title" : "grofep",
"_id" : ObjectId("57960aa8f9f9951c1fc923b1")
},
{
"resourceId" : ObjectId("5791be003fa3bedc15d3bddz"),
"userId" : ObjectId("5791be003fa3bedc15d3adcve"),
"title" : "mr3",
"_id" : ObjectId("57960aa8f9f9951c1fc923b2")
},
{
"resourceId" : ObjectId("5791be003fa3bedc15d3adde"),
"userId" : ObjectId("5791be003fa3bedc15d3adcve"),
"title" : "grofep23",
"_id" : ObjectId("57960aa8f9f9951c1fc923b3")
}
]
}
Now I want to get all the schedule of booking collection with their resource information.I want to fetch resources from categories table on the basis of booking schedule.
Desired output:
[
{
"name" : "1469491200000",
"resourceId" : ObjectId("5791be003fa3bedc15d3adde"),
"resourceTitle":"title",
"availability":false,
"bookings": [
{
"userId" : ObjectId("5791be003fa3bedc15d3adcve"),
"title" : "grofep",
"_id" : ObjectId("57960aa8f9f9951c1fc923b1")
},
{
"userId" : ObjectId("5791be003fa3bedc15d3adcve"),
"title" : "grofep23",
"_id" : ObjectId("57960aa8f9f9951c1fc923b3")
}
]
},
{
"name" : "1469491200000",
"resourceId" : ObjectId("5791be003fa3bedc15d3bddz"),
"resourceTitle":"mr3",
"availability":false,
"bookings": [
{
"userId" : ObjectId("5791be003fa3bedc15d3adcve"),
"title" : "mr3",
"_id" : ObjectId("57960aa8f9f9951c1fc923b2")
}
]
}
]
Help me to get this desired result.
Thanks.
i have the following document in a collection:
{
"_id" : 101,
"students" : [
{
"name" : "john",
"age" : 10,
"city":'CA'
},
{
"name" : "danial",
"age" : 15,
"city":'KA'
}
]
}
{
"_id" : 102,
"students" : [
{
"name" : "adam",
"age" : 20,
"city":'NY'
},
{
"name" : "johnson",
"age" : 12,
"city":'CA'
}
]
}
And i fire the following query:
db.data.find({'students.city':'CA'})
This returns me "students" objects from both the documents, as one instance matches the filter ("city"; 'CA') in both.
However, i desire to only get the matching array in the result. That is, i want the following result:
{
"_id" : 101,
"students" : [
{
"name" : "john",
"age" : 10,
"city":'CA'
}
]
}
{
"_id" : 102,
"students" : [
{
"name" : "johnson",
"age" : 12,
"city":'CA'
}
]
}
Please help.
You need to use $elemMatch in your projection:
> db.data.find({'students.city':'CA'},{ students:{ $elemMatch:{'city':'CA'} }})
{ "_id" : 101, "students" : [ { "name" : "john", "age" : 10, "city" : "CA" } ] }
{ "_id" : 102, "students" : [ { "name" : "johnson", "age" : 12, "city" : "CA" } ] }
Btw: I'd strongly suggest reading the Open letter to students with homework problems.
I think you should use an aggregation operation.
Here you have the documentation:
https://docs.mongodb.org/manual/aggregation/
And a similar question:
Retrieve only the queried element in an object array in MongoDB collection
I am trying to query for Mongo documents based on 1 many key value pairs over a large collection of documents.
I am storing the values in an array called descriptors. I cannot figure out to write the query to consistently return results.
Basically I am trying to write the following SQL query in Mongo
select * from descriptors where
(id=123 and value="Latest based on new infor")
or
(id=3221 and value="Latest new info")
I have tried the following:
db.collection.find({$or: [
{ descriptors:
{
'$elemMatch':
{
id: 123,
value: 'Latest based on new infor',
}
}
},
{ descriptors:
{
'$elemMatch':
{
id: 3221,
value: 'Latest new info',
}
}
}
]
}
Here are sample documents.
{
"_id" : ObjectId("569d62673b020a47f0401325"),
"descriptors" : [
{
"id" : 123,
"name" : "Version",
"value" : "Latest based on new infor",
"parent" : null
},
{
"id" : 345,
"name" : "Eligibility Criteria",
"value" : "Really qualified ",
"parent" : null
}
],
}
{
"_id" : ObjectId("569dac2e4e6247c01bbac47f"),
"descriptors" : [
{
"id" : 3221,
"name" : "Version",
"value" : "Latest new info",
"parent" : null
},
{
"id" : 345,
"name" : "Eligibility Criteria",
"value" : "Different Value",
"parent" : null
}
],
}
{
"_id" : ObjectId("56bce4df7aae8369d8fc705d"),
"descriptors" : [
{
"id" : 3221,
"name" : "Version",
"value" : "Latest based on new infor",
"parent" : null
},
{
"id" : 345.0,
"name" : "Eligibility Criteria",
"value" : "Really qualified",
"parent" : null
}
],
}
Any help would be appreciated,
gsvi