I have this dataModel
{
"_id": ObjectId("5f0a9c07b001406068c073c1"),
"EmailData" : [
{
"Attachments" : {
"Files" : [
{
"Name" : "a.txt"
},
{
"Name" : "b.txt"
},
{
"Name" : "c.txt"
}
]
}
}
]
}
I want to filter those documents that their name elements insides the Files array be exactly the same as a specific array.
Consider I have this array :{"a.txt", "b.txt", "c.txt"}. I want to write a query to compare what is inside the Files element with this array. In my example condition is met but if the array is like:
{"a.txt", "b.txt"}
It does not meet. I know I have to use multiple $elemMatch but it does not work. Is there any ways to write it without aggregate?
You are describing an exact comparison, try for example:
{'EmailData.Attachments.Files': [{Name: 'a.txt'},{Name: 'b.txt'},{Name:'c.txt'}]}
Or to allow matching in any order:
{'EmailData.Attachments.Files': {$all: [{Name: 'a.txt'},{Name: 'b.txt'},{Name:'c.txt'}], $size: 3}}
Related
I have a collection with documents like this
{
"_id" : ObjectId("59de9454e4b03289d79eeab4"),
"type" : "Draft",
.
.
.
headers
{
"payload" : [
{
"_id" : "ABC",
},
{
"_id" :"DEF",
}]
how should i store the _Id values in a variable like
result: ["ABC","DEF"]
I tried a query like this, but is not working
var result = []
db.request.find({"_id" : ObjectId("59de9454e4b03289d79eeab4")}).forEach(function(u) { result.push(u.headers.payload._id) })
Your input doc is a tad malformed but if payload is a single field subfield of headers i.e. it is not an array, and you want to do a $match or otherwise filter the material before you extract the _id values and you want all the _id values (not a distinct set) and returned neatly in a field called result then this does the trick:
db.foo.aggregate([
{$match: {"_id": 1}}
,{$project: {result: {$map: {
input: "$headers.payload",
as: "z",
in: "$$z._id"
}}
}}
]);
I am trying to do a find request in mongoDB with the condition:
"if element contains a list that contains exactly theses elements".
It makes more sense with an example:
{
"categories" : [
[
"dogs",
"cats"
],
[
"dogs",
"octopus"
]
]
}
I want to find an element with a category containing only "dogs" and "octopus".
find({ 'categories' : ['dogs','octopus']}) finds the element
find({ 'categories' : ['octopus','dogs']}) doesn't find and that's where my issue is since I don't care about the order in the list
The output would be all the elements with a category containing only "dogs" and "octopus"
I am not sure if it's possible but if it's not the two solutions I see would be to store them in alphabetic order (good but what if I need the order afterwards?) or to store/search all the possible orders (very ugly)
You can use aggregation pipelines
db.collection.aggregate([
{ "$unwind": "$categories" },
{ "$match": { "categories" : { "$all" : [ "dogs", "octopus" ]}}}
])
This gives you the following document
{
"_id" : ObjectId("54c6685e7cdaa3f3e4dd8def"),
"categories" : [ "dogs", "octopus" ]
}
I would like to ranked in descending order a list of documents in array names via their number value.
Here's the structure part of my collection :
_id: ObjectId("W")
var1: "X",
var2: "Y",
var3: "Z",
comments: {
names: [
{
number: 1;
},
{
number: 3;
},
{
number: 2;
}
],
field: Y;
}
but all my request with db.collection.find().sort( { "comments.names.number": -1 } ) doesn't work.
the desired output sort is :
{ "_id" : ObjectId("W"), "var1" : "X", "var3" : "Z", "comments" : { [ { "number" : 3 }, { "number" : 2 },{ "number" : 1 } ], "field": "Y" } }
Can you help me?
You need to aggregate the result, as below:
Unwind the names array.
Sort the records based on comments.names.number in descending
order.
Group the records based on the _id field.
project the required structure.
Code:
db.collection.aggregate([
{$unwind:"$comments.names"},
{$sort:{"comments.names.number":-1}},
{$group:{"_id":"$_id",
"var1":{$first:"$var1"},
"var2":{$first:"$var2"},
"var3":{$first:"$var3"},
"field":{$first:"$comments.field"},
"names":{$push:"$comments.names"}}},
{$project:{"comments":{"names":"$names","field":"$field"},"var1":1,
"var2":1,"var3":1}}
],{"allowDiskUse":true})
If your collection is large, you might want to add a $match criteria in the beginning of the aggregation pipeline to filter records or use (allowDiskUse:true), to facilitate sorting large number of records.
db.collection.aggregate([
{$match:{"_id":someId}},
{$unwind:"$comments.names"},
{$sort:{"comments.names.number":-1}},
{$group:{"_id":"$_id",
"var1":{$first:"$var1"},
"var2":{$first:"$var2"},
"var3":{$first:"$var3"},
"field":{$first:"$comments.field"},
"names":{$push:"$comments.names"}}},
{$project:{"comments":{"names":"$names","field":"$field"},"var1":1,
"var2":1,"var3":1}}
])
What The below query does:
db.collection.find().sort( { "comments.names.number": -1 } )
is to find all the documents, then sort those documents based on the number field in descending order. What this actually does is for each document get the comments.names.number field value which is the largest, for each document. And then sort the parent documents based on this number. It doesn't manipulate the names array inside each parent document.
You need update document for sort an array.
db.collection.update(
{ _id: 1 },
{
$push: {
comments.names: {
$each: [ ],
$sort: { number: -1 }
}
}
}
)
check documentation here:
http://docs.mongodb.org/manual/reference/operator/update/sort/#use-sort-with-other-push-modifiers
MongoDB queries sort the result documents based on the collection of fields specified in the sort. They do not sort arrays within a document. If you want the array sorted, you need to sort it yourself after you retrieve the document, or store the array in sorted order. See this old SO answer from Stennie.
Here is an example of a document from the collection I am querying
meteor:PRIMARY> db.research.findOne({_id: 'Z2zzA7dx6unkzKiSn'})
{
"_id" : "Z2zzA7dx6unkzKiSn",
"_userId" : "NtE3ANq2b2PbWSEqu",
"collaborators" : [
{
"userId" : "aTPzFad8DdFXxRrX4"
}
],
"name" : "new one",
"pending" : {
"collaborators" : [ ]
}
}
I want to find all documents within this collection with either _userId: 'aTPzFad8DdFXxRrX4' or from the collaborators array, userId: 'aTPzFad8DdFXxRrX4'
So I want to look though the collection and check if the _userId field is 'aTPzFad8DdFXxRrX4'. If not then check the collaborators array on the document and check if there is an object with userId: 'aTPzFad8DdFXxRrX4'.
Here is the query I am trying to use:
db.research.find({$or: [{_userId: 'aTPzFad8DdFXxRrX4'}, {collaborators: {$in: [{userId: 'aTPzFad8DdFXxRrX4'}]}}] })
It does not find the document and gives me a syntax error. What is my issue here? Thanks
The $in operator is basically a simplified version of $or but you really only have one argument here so you should not even need it. Use dot notation instead:
db.research.find({
'$or': [
{ '_userId': 'aTPzFad8DdFXxRrX4'},
{ 'collaborators.userId': 'aTPzFad8DdFXxRrX4'}
]
})
If you need more than one value then use $in:
db.research.find({
'$or': [
{ '_userId': 'aTPzFad8DdFXxRrX4'},
{ 'collaborators.userId': {
'$in': ['aTPzFad8DdFXxRrX4','aTPzFad8DdFXxRrX5']
}}
]
})
I am seriously baffled by mongodb's aggregate function. All I want is to find the newest document in my collection. Let's say each record has a field "created"
db.collection.aggregate({
$group: {
_id:0,
'id':{$first:"$_id"},
'max':{$max:"$created"}
}
})
yields the correct result, but I want the entire document in the result? How would I do that?
This is the structure of the document:
{
"_id" : ObjectId("52310da847cf343c8c000093"),
"created" : 1389073358,
"image" : ObjectId("52cb93dd47cf348786d63af2"),
"images" : [
ObjectId("52cb93dd47cf348786d63af2"),
ObjectId("52f67c8447cf343509d63af2")
],
"organization" : ObjectId("522949d347cf3402c3000001"),
"published" : 1392601521,
"status" : "PUBLISHED",
"tags" : [ ],
"updated" : 1392601521,
"user_id" : ObjectId("52214ce847cf344902000000")
}
In the documentation i found that the $$ROOT expression addresses this problem.
From the DOC:
http://docs.mongodb.org/manual/reference/operator/aggregation/group/#group-documents-by-author
query = [
{
'$sort': {
'created': -1
}
},
{
$group: {
'_id':null,
'max':{'$first':"$$ROOT"}
}
}
]
db.collection.aggregate(query)
db.collection.aggregate([
{
$group: {
'_id':"$_id",
'otherFields':{ $push: { fields: $ROOT } }
}
}
])
I think I figured it out. For example, I have a collection containing an array of images (or pointers). Now I want to find the document with the most images
results=[];
db.collection.aggregate([
{$unwind: "$images"},
{$group:{_id:"$_id", 'imagecount':{$sum:1}}},
{$group:{_id:"$_id",'max':{$max: "$imagecount"}}},
{$sort:{max:-1}},
{$group:{_id:0,'id':{$first:'$_id'},'max':{$first:"$max"}}}
]).result.forEach(function(d){
results.push(db.stories.findOne({_id:d.id}));
});
now the final array will contain the document with the most images. Since images is an array, I use $unwind, I then group by document id and $sum:1, pipe that into a $group that finds the max, pipe it into reverse $sort for max and $group out the first result. Finally I fetchOne the document and push it into the results array.
You should be using db.collection.find() rather than db.collection.aggregate():
db.collection.find().sort({"created":-1}).limit(1)