I have a structure with document, and lines. A line has a reference to it's document. However some lines can also have a reference to another line.
I want to make a query to retrieve all the lines involved in a documents (meaning lines directly linked, and the referenced lines).
Example
{_id:1, doc:1 },
{_id:3, doc:1, linkedLine:4},
{_id:4, doc:2 },
{_id:5, doc:2 },
I would like to obtain
linesOfDoc(1) = {_id:1, doc:1},{_id:3, doc:1, linkedLine:4},{_id:4, doc:2 }
I could be done getting first lines with doc=1, the doing a loop and getting the linked lines if present.
But is that possible to do this in one mongodb query ?
Regards
You can not do joins with mongo, exactly as you would do with sql, but you can get close with aggregation pipeline.
You got all the data in one query, but you need to flatten it farther to get the exact result you specified.
MONGO> db.playground.find()
{ "_id" : 1, "doc" : 1 }
{ "_id" : 3, "doc" : 1, "linkedLine" : 4 }
{ "_id" : 4, "doc" : 2 }
MONGO> db.playground.aggregate([{ $lookup: { from: "playground", localField: "linkedLine", foreignField: "_id", as: "embeddedLinkedLine"}}, { $match: { doc: <id of the document youre looking for> }}])
{ "_id" : 1, "doc" : 1, "embeddedLinkedLine" : [ ] }
{ "_id" : 3, "doc" : 1, "linkedLine" : 4, "embeddedLinkedLine" : [ { "_id" : 4, "doc" : 2 } ] }
Related
i have some collections for our project.
Casts collection contains movie casts
Contents collection contains movie contents
i want to run aggregate lookup for get information about movie casts with position type.
i removed collections details unnecessary fields.
Casts details:
{
"_id" : ObjectId("5a6cf47415621604942386cd"),
"fa_name" : "",
"en_name" : "Ehsan",
"fa_bio" : "",
"en_bio" : ""
}
Contents details:
{
"_id" : ObjectId("5a6b8b734f1408137f79e2cc"),
"casts" : [
{
"_id" : ObjectId("5a6cf47415621604942386cd"),
"fa_fictionName" : "",
"en_fictionName" : "Ehsan2",
"positionType" : {
"id" : 3,
"fa_name" : "",
"en_name" : "Director"
}
},
{
"_id" : ObjectId("5a6cf47415621604942386cd"),
"fa_fictionName" : "",
"en_fictionName" : "Ehsan1",
"positionType" : {
"id" : 3,
"fa_name" : "",
"en_name" : "Writers"
}
}
],
"status" : 0,
"created" : Timestamp(1516997542, 4),
"updated" : Timestamp(1516997542, 5)
}
when i run aggregate lookup with bellow query, in new generated lookup array only one casts contents If in accordance with above casts array value aggregate lookup should return two casts content with two type. in casts array value exists two type of casts, 1) writers and directors. but returned director casts content. _casts should contains two object not one object!
aggregate lookup query:
{$lookup:{from:"casts",localField:"casts._id",foreignField:"_id",as:"_casts"}}
result:
{
"_id" : ObjectId("5a6b8b734f1408137f79e2cc"),
"casts" : [
{
"_id" : ObjectId("5a6cf47415621604942386cd"),
"fa_fictionName" : "",
"en_fictionName" : "Ehsan2",
"positionType" : {
"id" : 3,
"fa_name" : "",
"en_name" : "Director"
}
},
{
"_id" : ObjectId("5a6cf47415621604942386cd"),
"fa_fictionName" : "",
"en_fictionName" : "Ehsan1",
"positionType" : {
"id" : 3,
"fa_name" : "",
"en_name" : "Writers"
}
}
],
"_casts" : [
{
"_id" : ObjectId("5a6cf47415621604942386cd"),
"fa_name" : "",
"en_name" : "Ehsan",
"fa_bio" : "",
"en_bio" : ""
}
],
"status" : 0,
"created" : Timestamp(1516997542, 4),
"updated" : Timestamp(1516997542, 5)
}
EDIT-1
finally my problem is solved. i have only one problem with this query, this query doesn't show root document fields. finally solve this problem. finally query exists in EDIT-2.
query:
db.contents.aggregate([
{"$unwind":"$casts"},
{"$lookup":{"from":"casts","localField":"casts._id","foreignField":"_id","as":"casts.info"}},
{"$unwind":"$casts.info"},
{"$group":{"_id":"$_id", "casts":{"$push":"$casts"}}},
])
EDIT-2
db.contents.aggregate([
{"$unwind":"$casts"},
{"$lookup":{"from":"casts","localField":"casts._id","foreignField":"_id","as":"casts.info"}},
{"$unwind":"$casts.info"},
{$group:{"_id":"$_id", "data":{"$first":"$$ROOT"}, "casts":{"$push":"$casts"}}},
{$replaceRoot:{"newRoot":{"$mergeObjects":["$data",{"casts":"$casts"}]}}},
{$project:{"casts":0}}
]).pretty()
This is expected behavior.
From the docs,
If your localField is an array, you may want to add an $unwind stage
to your pipeline. Otherwise, the equality condition between the
localField and foreignField is foreignField: { $in: [
localField.elem1, localField.elem2, ... ] }.
So to join each local field array element with foreign field element you have to $unwind the local array.
db.content.aggregate([
{"$unwind":"$casts"},
{"$lookup":{"from":"casts","localField":"casts._id","foreignField":"_id","as":"_casts"}}
])
Vendor Collection
Items Collection
db.items.aggregate([
{ $match:
{"item_id":{$eq:"I001"}}
},
{
$lookup:{
from:"vendor",
localField:"vendor_id",
foreignField:"vendor_id",
as:"vendor_details"
}
},
{
$unwind:"$vendor_details"
},
{
$project:{
"_id":0,
"vendor_id":0,
"vendor_details.vendor_company_description":0,
"vendor_details._id":0,
"vendor_details.country":0,
"vendor_details.city":0,
"vendor_details.website":0
}
}
]);
Output
Your Casts collection shows only 1 document. Your Contents collection, likewise, shows only 1 document.
This is 1 to 1 - not 1 to 2. Aggregate is working as designed.
The Contents document has 2 "casts." These 2 casts are sub-documents. Work with those as sub-documents, or re-design your collections. I don't like using sub-documents unless I know I will not need to use them as look-ups or join on them.
I would suggest you re-design your collection.
Your Contents collection (it makes me think of "Movies") could look like this:
_id
title
releaseDate
genre
etc.
You can create a MovieCasts collection like this:
_id
movieId (this is _id from Contents collection, above)
castId (this is _id from Casts collection, below)
Casts
_id
name
age
etc.
I'm quite new to mongodb and there is one thing I can't solve right now:
Let's pretend, you have the following document structure:
{
"_id": ObjectId("some object id"),
name: "valueName",
options: [
{idOption: "optionId", name: "optionName"},
{idOption: "optionId", name: "optionName"}
]
}
And each document can have multiples options that are already classified.
I'm trying to get all the documents in the collection that have, at least one, of the multiples options that I pass for the query.
I was trying with the operator $elemMatch something like this:
db.collectioName.find({"options.name": { $elemMatch: {"optName1","optName2"}}})
but it never show me the matches documents.
Can someone help and show me, what I'm doing wrong?
Thanks!
Given a collection which contains the following documents:
{
"_id" : ObjectId("5a023b8d027b5bd06add627a"),
"name" : "valueName",
"options" : [
{
"idOption" : "optionId",
"name" : "optName1"
},
{
"idOption" : "optionId",
"name" : "optName2"
}
]
}
{
"_id" : ObjectId("5a023b9e027b5bd06add627d"),
"name" : "valueName",
"options" : [
{
"idOption" : "optionId",
"name" : "optName3"
},
{
"idOption" : "optionId",
"name" : "optName4"
}
]
}
This query ...
db.collection.find({"options": { $elemMatch: {"name": {"$in": ["optName1"]}}}})
.. will return the first document only.
While, this query ...
db.collection.find({"options": { $elemMatch: {"name": {"$in": ["optName1", "optName3"]}}}})
...will return both documents.
The second example (I think) meeets this requirement:
I'm trying to get all the documents in the collection that have, at least one, of the multiples options that I pass for the query.
I have a really simple question which has troubled me for some time. I have a list of objects containing an array of Measurements, where each of these contains a time and multiple values like below:
{
"_id" : ObjectId("5710ed8129c7f31530a537bc"),
"Measurements" : [
{
"_t" : "Measurement",
"_time" : ISODate("2016-04-14T12:31:52.584Z"),
"Measurement1" : 1
"Measurement2" : 2
"Measurement3" : 3
},
{
"_t" : "DataType",
"_time" : ISODate("2016-04-14T12:31:52.584Z"),
"Measurement1" : 4
"Measurement2" : 5
"Measurement3" : 6
},
{
"_t" : "DataType",
"_time" : ISODate("2016-04-14T12:31:52.584Z"),
"Measurement1" : 7
"Measurement2" : 8
"Measurement3" : 9
} ]
},
{
"_id" : ObjectId("5710ed8129c7f31530a537cc"),
"Measurements" : [
{
"_t" : "Measurement",
"_time" : ISODate("2016-04-14T12:31:52.584Z"),
"Measurement1" : 0
....
I want to create a query which projects the following data set into the one below. For example, query for Measurement1 and create an array of objects containing the time and value of Measurement1 (see below) via mongo aggregation framework.
{ "Measurement": [
{
"Time": ISODate("2016-04-14T12:31:52.584Z"),
"Value": 1
}
{
"Time": ISODate("2016-04-14T12:31:52.584Z"),
"Value": 4
}
{
"Time": ISODate("2016-04-14T12:31:52.584Z"),
"Value": 7
}
]}
Seems like a pretty standard operation, so I hope you guys can shed some light on this.
You can do this by first unwinding the Measurements array for each doc and then projecting the fields you need and then grouping them back together:
db.test.aggregate([
// Duplicate each doc, once per Measurements array element
{$unwind: '$Measurements'},
// Include and rename the desired fields
{$project: {
'Measurements.Time': '$Measurements._time',
'Measurements.Value': '$Measurements.Measurement1'
}},
// Group the docs back together to reassemble the Measurements array field
{$group: {
_id: '$_id',
Measurements: {$push: '$Measurements'}
}}
])
I have a MongoDB document like this example doc:
{
"_id" : "A",
"articleNumber" : "0123456",
"shopDependentProperties" :
{
"shop" : "DE",
"foo" : "foo",
"bar" : "bar"
}
}
and want to pull out the properties of shopDependentProperties, to have the following result
{
"_id" : "A",
"articleNumber" : "0123456",
"foo" : "foo",
"bar" : "bar"
}
In MongoDB Shell i can solve it this way:
db.test.aggregate(
[
{
$project:
{
_id : "$_id",
articleNumber : "$articleNumber",
foo:"$shopDependentProperties.foo",
bar:"$shopDependentProperties.bar"
}
}
]
)
But: In Spring Data MongoDB i can't extract the embedded document contents.
I tried many combinations, nothing worked. For example:
ProjectionOperation projection = Aggregation.project("_id");
projection.andExpression("shopDependentProperties.foo").as("foo");
projection.andExpression("shopDependentProperties.bar").as("bar");
System.out.println(projection.toDBObject(Aggregation.DEFAULT_CONTEXT));
will ignore the shopDependentProperties.shop stuff and just print out
{ "$project" : { "_id" : 1}}
Any suggestions?
Thx
Haven't tested this, but as of
http://docs.mongodb.org/manual/reference/operator/aggregation/project/
you specify included / excluded fields like this:
db.test.aggregate(
[
{
$project:
{
_id : "$_id",
articleNumber : 1,
"shopDependentProperties.foo": 1,
"shopDependentProperties.bar": 1
}
}
]
)
Further down they explain, how to include embedded documents in the projection result.
I know how to do it in MongoDB, the problem was about doing the same thing in Spring Data.
But it works the same way, why didn't I try that before?
Solution:
ProjectionOperation projection = Aggregation.project(
"brandName",
"$shopDependentProperties.foo",
"$shopDependentProperties.bar" );
I have a collection that stored information about devices like the following:
/* 1 */
{
"_id" : {
"startDate" : "2012-12-20",
"endDate" : "2012-12-30",
"dimensions" : ["manufacturer", "model"],
"metrics" : ["deviceCount"]
},
"data" : {
"results" : "1"
}
}
/* 2 */
{
"_id" : {
"startDate" : "2012-12-20",
"endDate" : "2012-12-30",
"dimensions" : ["manufacturer", "model"],
"metrics" : ["deviceCount", "noOfUsers"]
},
"data" : {
"results" : "2"
}
}
/* 3 */
{
"_id" : {
"dimensions" : ["manufacturer", "model"],
"metrics" : ["deviceCount", "noOfUsers"]
},
"data" : {
"results" : "3"
}
}
And I am trying to query the documents using the _id field which will be unique. The problem I am having is that when I query for all the different attributes as in:
db.collection.find({$and: [{"_id.dimensions":{ $all: ["manufacturer","model"], $size: 2}}, {"_id.metrics": { $all:["noOfUsers","deviceCount"], $size: 2}}]});
This matches 2 and 3 documents (I don't care about the order of the attributes values), but I would like to only get 3 back. How can I say that there should not be any other attributes to _id than those that I specify in the search query?
Please advise. Thanks.
Unfortunately, I think the closest you can get to narrowing your query results to just unordered _id.dimensions and unordered _id.metrics requires you to know the other possible fields in the _id subdocument field, eg. startDate and endDate.
db.collection.find({$and: [
{"_id.dimensions":{ $all: ["manufacturer","model"], $size: 2}},
{"_id.metrics": { $all:["noOfUsers","deviceCount"], $size: 2}},
{"_id.startDate":{$exists:false}},
{"_id.endDate":{$exists:false}}
]});
If you don't know the set of possible fields in _id, then the other possible solution would be to specify the exact _id that you want, eg.
db.collection.find({"_id" : {
"dimensions" : ["manufacturer", "model"],
"metrics" : ["deviceCount", "noOfUsers"]
}})
but this means that the order of _id.dimensions and _id.metrics is significant. This last query does a document match on exact BSON representation of _id.