I'm searching for a value in an array of a sub arrays. What will the code in C# look like?
db.File.find({
Properties: {
$elemMatch: {
$elemMatch: {
$in:
['AWS-Uploaded']
}
}
}
});
A simplified version of the documents looks like this:
{
"_id" : ObjectId("4f3b83acec76021c6827769e"),
"Extension" : ".mov",
"Length" : NumberLong(7910975),
"Properties" : [
["MediaId", "20898180"],
["AWS-Uploaded", "11/08/2013 16:15:50"]
]
}
For the query object for returning documents where an array element exists, this should do the job
Query.ElemMatch("Properties",
Query.Exists('AWS-Uploaded',true)
);
To use ElemMatch with query operators, like where MediaId=20898180 would be:
Query.ElemMatch("Properties",
Query.EQ('MediaId',20898180)
);
Hope that helps
Related
This question already has answers here:
Find in Double Nested Array MongoDB
(2 answers)
Spring data Match and Filter Nested Array
(1 answer)
Closed 3 years ago.
I'm looking to search into my collection and retreive only element who matched Criteria.
Here is my collection :
{
"_id" : "id",
"name" : "test",
"groupUsers" : [
{
"name" : "blabla",
"toys" : [
{
"createdAt" : ISODate("2019-10-30T12:59:41.409Z"),
},
{
"createdAt" : ISODate("2019-11-30T12:59:10.409Z"),
},
{
"createdAt" : ISODate("2019-12-30T12:59:12.409Z"),
}
],
"createdAt" : ISODate("2019-10-30T12:33:39.036Z")
},
{
"name" : "blabla2",
"toys" : [
{
"createdAt" : ISODate("2019-10-32T12:59:41.409Z"),
},
{
"createdAt" : ISODate("2019-11-30T12:59:56.409Z"),
},
{
"createdAt" : ISODate("2019-12-30T12:59:15.409Z"),
}
],
"createdAt" : ISODate("2019-10-32T12:33:39.036Z")
}
],
}
I want to retreive the whole collection but it depends when the user was added to the group for example, user blabla2 (in the example above) will only get the whole group but with only the two last toys of the first user in the response.
Anyway, I guess it's something really basic but I don't know why I can't figure it out.
What I'm Doing
I'm doing a first query to get the current user and get when he was added in the group (notice that the date gets converted into java Date Util here).
Aggregation groupAgg = newAggregation(match(Criteria.where("_id").is(groupId).and("groupUsers.userId").is(userId)));
GroupUser groupUser = mongoTemplate.aggregate(groupAgg, Group.class, GroupUser.class).getUniqueMappedResult();
In a second query, I want to get the whole document but only with the Criteria that I define before.
MatchOperation matchedGroup = match(new Criteria("_id").is(groupId));
MatchOperation matchedToys = match(
new Criteria("groupUsers.toys.createdAt").gte(groupUser.getCreatedAt()));
Aggregation aggregation = newAggregation(matchedGroup, matchedToys);
AggregationResults<Group> result = mongoTemplate.aggregate(aggregation, Group.class, Group.class);
Group group = result.getUniqueMappedResult();
This query doesn't work, and I'm looking to something like even if there is no match (for example, none toys has been created yet), it still return the group basic response and not null.
Maybe I need to unwind the nested array ?
Any help is appreciate. I'm using spring data.
Try this query
db.testers.aggregate([
{
$addFields:{
"groupUsers":{
$map:{
"input":"$groupUsers",
"as":"doc",
"in":{
$mergeObjects:[
"$$doc",
{
"toys":{
$filter:{
"input":"$$doc. toys",
"as":"sn",
"cond": {
"$and": [
{ "$gte": [ "$$sn.createdAt", ISODate('2015-06-17T10:03:46.000Z') ] },
]
}
}
}
}
]
}
}
}
}
}
]).pretty()
I've an Application collection with documents like this:
{
"_id" : "TAIS",
"commonUserName" : "TAIS",
"scopes" : [
DBRef("Scope", "GEN_ECO"),
DBRef("Scope", "GEN_PRE")
]
}
So, Scope collection documents are like:
{
"_id" : "GEN_PRE",
"code" : "1DPVE000"
}
Here, there's another third collection, Reference:
{
"_id": "sdfls2",
"app" : "TAIS"
}
I need to build a query in order to look up references where have been reference.app belongs to a given %scope%.
Any ideas?
You can use $lookup to "join" collections.
e.g.
db.applications.aggregate([
{
$lookup:
{
from: "third_collection",
localField: "_id",
foreignField: "app",
as: "app_with_reference"
}
}
])
More:
https://docs.mongodb.com/manual/reference/operator/aggregation/lookup/#pipe._S_lookup
After asking question to understand a bit more of the aggregation framework in MongoDB I finally found the way to do aggregation for my need (thanks to a StackExchange user)
So basically here is a document from my collection:
{
"_id" : ObjectId("s4dcsd5s4d6c54s6d"),
"items" : [
{
type : "TYPE_1",
text : "blablabla"
},
{
type : "TYPE_2",
text : "blablabla"
},
{
type : "TYPE_3",
text : "blablabla"
},
{
type : "TYPE_1",
text : "blablabla"
},
{
type : "TYPE_2",
text : "blablabla"
},
{
type : "TYPE_1",
text : "blablabla"
}
]
}
The idea was to be able to filter only some elements of my collections (avoiding Type 2 and 3). In fact I have more than 30 types and 6 are not allowed but for simplicity I made this example.
So the aggregation command in command line is this one:
db.history.aggregate([{
$match: {
_id: ObjectId("s4dcsd5s4d6c54s6d")
}
}, {
$unwind: '$items'
}, {
$match: {
'items.type': { '$nin': [ "TYPE_2" , "TYPE_3"] }
}
},
{ $limit: 10 }
]);
With this I am able to retrieve the 10 elements items of this document which do not match TYPE_2 and TYPE_3
However when I am using spring data there is no output. I looked a bit at the example to build mine but its still not working.
So I did:
Aggregation aggregation = newAggregation(
match(Criteria.where("id").is(myID)),
unwind("items"),
match(Criteria.where("items.type").nin(ignoreditemstype)),
limit(3),
skip(offsetLong)
);
AggregationResults<PersonnalHistory> results = mongAccess.getOperation().aggregate(query,
"items", PersonnalHistory.class);
PersonnalHistory is marked with annotation #Document(collection = "history") and id with the #id annotation
ignoreditemstype is a list containing TYPE_2 and TYPE_3
Here is what I have in the toString method of aggregation:
{
"aggregate" : "__collection__" ,
"pipeline" : [
{ "$match": { "id" : "s4dcsd5s4d6c54s6d"} },
{ "$unwind": "$items"},
{ "$match": { "items.type": { "$nin" : [ "TYPE_2" , "TYPE_3" ] } } },
{ "$limit" : 3},
{ "$skip" : 0 }
]
}
I tried a lot of stuff (to have at least an answer :) ) like removing id or the nin:
aggregation = newAggregation(
unwind("items"),
match(Criteria.where("items.type").nin(ignoreditemstype)),
limit(3),
skip(offsetLong)
);
aggregation = newAggregation(
match(Criteria.where("id").is(myid)),
unwind("items")
);
For information when I do a simple query like:
query.addCriteria(Criteria.where("id").is(myID));
My document is returned. However I have thousands of items. So I just want to have the 15 first (in fact the 15 first are the 15 last added)
Do you maybe see what I am doing wrong?
Yeah looks like you are passing simple String while it is expecting ObjectId
Aggregation aggregation = newAggregation(
match(Criteria.where("_id").is(new ObjectId(myID))),
unwind("items"),
match(Criteria.where("items.type").nin(ignoreditemstype)),
limit(3),
skip(offsetLong)
);
Now the question is why it works with simple query, my answer would be because spring-data driver is not that mature at least not with aggregation pipeline.
I am trying to do a SpanFirstQuery with NEST, as described in:
https://www.elastic.co/guide/en/elasticsearch/reference/1.4/query-dsl-span-first-query.html
The SpanFirstQuery class has a Match property, but the Match property is an ISpanQuery which has a SpanFirst property that is a ISpanFirstQuery. That seems to be an endless loop.
I am confused..
How to do a spanfirstquery with NEST?
Thanks.
A span_first query in NEST can be done very simply like this:
var s = new SearchDescriptor<ElasticsearchProject>()
.Query(q => q
.SpanFirst(sf=>sf
.MatchTerm(f => f.User, "kimchy")
.End(3)
)
);
That will produce the same query as depicted in the official documentation:
{
"span_first" : {
"match" : {
"span_term" : { "user" : "kimchy" }
},
"end" : 3
}
}
I am new to mongo db so excuse me if this is rather trivial. I would really appreciate the help.
The idea is to generate a histogram over some specific values. In that case the mime types of some files. For that I am using a map reduce job.
I have a mongo with documents in the following form:
{
"_id" : ObjectId("4fc5ed3e67960de6794dd21c"),
"name" : "some name",
"uid" : "some app specific uid",
"collection" : "some name",
"metadata" : [
{
"key" : "key1",
"value" : "Plain text",
"status" : "SINGLE_RESULT",
},
{
"key" : "key2",
"value" : "text/plain",
"status" : "SINGLE_RESULT",
},
{
"key" : "key3",
"value" : 3469,
"status" : "OK",
}
]
}
Please note, that in almost every document there are more metadata key values.
Map Reduce job
I tried doing the following:
function map() {
var mime = "";
this.metadata.forEach(function (m) {
if (m.key === "key2") {
mime = m.value;}
});
emit(mime, {count:1});
}
function reduce() {
var res = {count:0};
values.forEach(function (v) {res.count += v.count;});
return res;
}
db.collection.mapReduce(map, reduce, {out: { inline : 1}})
This seems to work for a small number of documents (~15K) but the problem is that iterating through all metadata key values takes a lot of time during the mapping phase. When running this on more documents (~1Mio) the operation takes for ever.
So my question is:
Is there some way in which I can emit the mime type (the value) directly instead of iterating through all keys and selecting it? Or is there a better way to write a map reduce functions.
Something like emit (this.metadata.value {$where this.metadata.key:"key2"}) or similar...
Thanks for your help!
Two thoughts ...
First thought: How attached are you to this document schema? Could you instead have the metadata field value as an embedded document rather than an embedded array, like so:
{
"_id" : ObjectId("4fc5ed3e67960de6794dd21c"),
"name" : "some name",
"uid" : "some app specific uid",
"collection" : "some name",
"metadata" : {
"key1" : {
"value" : "Plain text",
"status" : "SINGLE_RESULT"
},
"key2": {
"value" : "text/plain",
"status" : "SINGLE_RESULT"
},
"key3" : {
"value" : 3469,
"status" : "OK"
}
}
}
Then your map step does away with the loop entirely:
function map() {
emit( this.metadata["key2"].value, { count : 1 } );
}
At that point, you might even be able to cast this as a "group" command rather than a "mapReduce".
Second thought: Absent a schema change like that, particularly if "key2" appears early in the metadata array, you could at least exit the loop eagerly once the key is found to save yourself some iterations, like so:
function map() {
var mime = "";
this.metadata.forEach(function (m) {
if (m.key === "key2") {
mime = m.value;
break;
}
});
emit(mime, {count:1});
}
Not sure if either path is the key to victory, but hopefully helpful thoughts. Best of luck!