I've got a document in MongoDB which has a multi-dimensional array as shown below.
{"_id":1,
"name":"Johnson",
"card":[
["",12,25,"","",52,60,"",86],
[1,17,29,"",43,"","","",89],
[3,"","",34,45,"",62,70,""]
]
}
I'm looking for a query that returns the index of a particular element in the array, for example, say 29 whose index is [1][2] but when i queried as:
> db.test.aggregate([{$project:{index:{$indexOfArray:["$card",29]}}}])
i got the result as:
{ "_id" : 1, "index" : -1 }
which is not true. I found that this query method works only for one-dimensional array and I'm unable to figure out how to find the index of multi-dimensional array in MongoDB.
Any help will be appreciated.
Thankyou
Not exactly clear on what datatype [1][2] is, so rendering the desired output is a bit of a challenge. Here is a attempt to help your question...
Test Data
db.collection.insert(
{
"name":"Johnson",
"card":[
["", 12, 25, "", "", 52, 60, "", 86],
[1, 17, 29, "", 43, "", "", "", 89],
[3, "", "", 34, 45, "", 62, 70, ""]
]
}
(Assumes a hard-coded value of 29 to search for)
Aggregate
EDIT 2021-12-09 - ADDED $project TO CAST RESULTS AS INTEGER. WAS NumberLong()
db.collection.aggregate([
{
$unwind:
{
path: "$card",
includeArrayIndex: "outerIndex"
}
},
{
$unwind:
{
path: "$card",
includeArrayIndex: "innerIndex"
}
},
{
$match:
{
"card": 29
}
},
{
$project:
{
name: 1,
card: 1,
outerIndex: { $convert: { input: "$outerIndex", to: "int" } },
innerIndex: { $convert: { input: "$innerIndex", to: "int" } }
}
}
])
Results
[
{
_id: ObjectId("61b13476c6c466d7d1ea9b5e"),
name: 'Johnson',
card: 29,
outerIndex: 1,
innerIndex: 2
}
]
Unwanted fields can be supressed with another $project stage, but I did not include it here since I was not clear on desired output.
Related
I want to get an aggregation/count of the occurrence of all items in an array across all documents. I've tried looking up examples but none of them seem to cover this scenario exactly or go about it in a very obtuse way.
Here's a simple idea of the document model i'm working with. The itemIds array within each object is always unique (no repeated values):
[{
_id:1,
itemIds:[3, 4, 6, 12]
},
{
_id:2,
itemIds:[4, 12]
},
{
_id:3,
itemIds:[3, 4, 8, 9, 12]
}]
I need the counts of each of these summed up (doesn't have to be this exact format but just giving a general idea of what I need):
{
itemsCount:[
{
itemId:3,
count:2
},
{
itemId:4,
count:3
},
{
itemId:6,
count:1
},
{
itemId:8,
count:1
},
{
itemId:9,
count:1
},
{
itemId:12,
count:3
}
]
}
Please try this :
db.yourCollection.aggregate([
{$project : {'itemIds' : 1, _id :0}},
{$unwind : '$itemIds'},
{$group : {'_id': '$itemIds', count :{$sum :1}}}
])
Document Structure
{
_id: 5,
grades: [
{ grade_ : 80, mean: 75, std: 8 },
{ mean: 90, std: 5 },
{ mean: 85, std: 3 }
]
}
As per above document structure in mongodb i want rename key grade_ to grade
db.collection.update({"_id":5},{"$rename":{"grades.grade_":"grades.grade"}},{"upsert":false,"multi":true})
which gives below error
"writeError" : {
"code" : 28,
"errmsg" : "cannot use the part (grades of grades.grade_) to traverse the element ({grades: [ { grade_: 80.0, mean: 75.0, std: 8.0 }, { mean: 90.0, std: 5.0 }, { mean: 85.0, std: 3.0 } ]})"
}
I want to rename key grade_ to grade, expected output
{
_id: 5,
grades: [
{ grade : 80, mean: 75, std: 8 },
{ mean: 90, std: 5 },
{ mean: 85, std: 3 }
]
}
As per MongoDB documentation: ($rename does not work if these fields are in array elements.)
For fields in embedded documents, the $rename operator can rename these fields as well as move the fields in and out of embedded documents. $rename does not work if these fields are in array elements.
So, you need to write your custom logic to update.
db.collection.find({
"grades.grade_": { $exists : 1 }
}).forEach( function( doc ) {
for( i=0; i < doc.grades.length; i++ ) {
if(doc.grades[i].grade_ != undefined) {
doc.grades[i].grade = doc.grades[i].grade_;
delete doc.grades[i].grade_;
}
}
db.collection.update({ _id : doc._id }, doc);
});
$rename do not works in an array. So,you can use Aggregate framework's $addField to rename fields in an array.
db.collection.aggregate([
{
$addFields: {
grades: {
$map: {
input: "$grades",
as: "grade",
in: {
grade: "$$grade.grade_",
mean: "$$grade.mean",
std: "$$grade.std"
}
}
}
}
}
])
Output:
[
{
"_id": 5,
"grades": [
{"grade": 80,"mean": 75,"std": 8},
{"mean": 90,"std": 5},
{"mean": 85,"std": 3}
]
}
]
Let's say my collection has documents with ExpName field and Rname field. Expname are all of the type - exp_1, exp_2 etc. Rname is a character string with 4 dashes for example. "As-34rt-d3r5-4453f-er4"
I need to aggregate based on experiment name and removing the text between the last two dashes. In the example I gave above that would be "As-34rt-d3r5"
question 1) how do i incorporate this in one table?
question 2) i solved this in a dirty fashion for one exp, because it seemed like the number of characters was almost the same, so I could just take the first 13 characters which seemed like it was the the substring omitting the last two dashes. Is there a correct way to do this if the text was not so uniform?
db.getCollection('rest01').aggregate(
{$match : {ExpName : "exp_1"}},
{$group: {_id :"$ExpName",_id : {$substr : ["$RName", 0,13]}, total: { $sum:1 }}
})
Ideally I would like to have a result that says Expname, Rnamesubstring, count. This code snippet was for exp_1 one alone. Is it even possible to get it all in one result?
Here is how you could do that:
db.getCollection('rest01').aggregate({
$project: {
"ExpName": 1,
"splitRName": { $split: [ "$RName", "-" ] } // add an array with the constituents of your dash-delimited string id as a new field "splitRName"
}
}, {
$group: {
_id: { // our group id shall be made up of both...
"ExpName": "$ExpName", // ...the "ExpName" field...
"Rnamesubstring": { // and some parts of the "RName" field
$concat:
[
{ $arrayElemAt: [ "$splitRName", 0 ] },
"-",
{ $arrayElemAt: [ "$splitRName", 1 ] },
"-",
{ $arrayElemAt: [ "$splitRName", 2 ] }
]
}
},
total: { $sum: 1 }
}
})
In case you want to do it in MongoDB v3.2 (as stated in your comment), here is something that is not exactly pretty but works:
db.getCollection('rest01').aggregate({
$group: {
_id: { // our group id shall be made up of both...
"ExpName": "$ExpName", // ...the "ExpName" field...
"Rnamesubstring": {
$substr:
[
"$RName",
0,
{
$ifNull:
[
{
$arrayElemAt:
[{
$filter: {
input: {
$map: {
input: [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 /* add numbers as required */ ],
as: "index",
in: {
$cond: {
if: { $eq: [ "-", { $substr: [ "$RName", "$$index", 1 ] } ] }, // if the string we look at is a dash...
then: "$$index", // ...then let's remember it
else: null // ...otherwise ignore it
}
}
}
},
as: "item",
cond: { $ne: [ null, "$$item" ] } // get rid of all null values
}
},
2 ] // we want the position of the third dash in the string (only)
},
1000 // in case of a malformed RName (wrong number of dashes or completely missing) we want the entire substring
]
}
]
}
},
total: { $sum: 1 }
}
})
Update 2: You seem to be having some data related issues as per your comments (so either missing RName values or improperly structured ones, i.e. without the required number of sections with dashes in between). I have updated the above statement for v3.2 to deal with these rows. You may want to find out, though, which rows actually cause this behaviour. They can be easily identified using the following statement:
db.getCollection('rest01').aggregate({
$project: {
_id: 1,
RName: 1,
"Rnamesubstring": {
$arrayElemAt:
[{
$filter: {
input: {
$map: {
input: [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 /* add numbers as required */ ],
as: "index",
in: {
$cond: {
if: { $eq: [ "-", { $substr: [ "$RName", "$$index", 1 ] } ] }, // if the string we look at is a dash...
then: "$$index", // ...then let's remember it
else: null // ...otherwise ignore it
}
}
}
},
as: "item",
cond: { $ne: [ null, "$$item" ] } // get rid of all null values
}
},
2 ] // we want the position of the third dash in the string (only)
}
}
}, {
$match: { "Rnamesubstring": { $exists:false } }
})
This question already has answers here:
Query for documents where array size is greater than 1
(14 answers)
Closed 6 years ago.
I have a collection like
{
"_id": "201503110040020021",
"Line": "1", // several documents may have this Line value
"LineStart": ISODate("2015-03-11T06:49:35.000Z"),
"SSCEXPEND": [{
"Secuence": 10,
"Title": 1,
},
{
"Secuence": 183,
"Title": 613,
},
...
],
} {
"_id": "201503110040020022",
"Line": "1", // several documents may have this Line value
"LineStart": ISODate("2015-03-11T06:49:35.000Z"),
"SSCEXPEND": [{
"Secuence": 10,
"Title": 1,
},
],
}
SSCEXPEND is an array. I am trying to count the size of SSC array and project if the count is greater than or equal to 2. My query is something like this
db.entity.aggregate(
[
{
$project: {
SSCEXPEND_count: {$size: "$SSCEXPEND"}
}
},
{
$match: {
"SSCEXPEND_count2": {$gte: ["$SSCEXPEND_count",2]}
}
}
]
)
I am expecting the output to be only the the first document whose array size is greater than 2.
Project part is working fine and I am able to get the counts but I need to project only those which has count greater than or equal to two but my match part is not working. Can any one guide me as where am I going wrong?
You need to project the other fields and your $match pipeline will just need to do a query on the newly-created field to filter the documents based on the array size. Something like the following should work:
db.entity.aggregate([
{
"$project": {
"Line": 1,
"LineStart": 1, "SSCEXPEND": 1,
"SSCEXPEND_count": { "$size": "$SSCEXPEND" }
}
},
{
"$match": {
"SSCEXPEND_count": { "$gte": 2 }
}
}
])
Sample Output:
/* 0 */
{
"result" : [
{
"_id" : "201503110040020021",
"Line" : "1",
"LineStart" : ISODate("2015-03-11T06:49:35.000Z"),
"SSCEXPEND" : [
{
"Secuence" : 10,
"Title" : 1
},
{
"Secuence" : 183,
"Title" : 613
}
],
"SSCEXPEND_count" : 2
}
],
"ok" : 1
}
This is actually a very simple query, where the trick is to use a property of "dot notation" in order to test the array. All you really need to ask for is documents where the array index of 2 $exists, which means the array must contain 3 elements or more:
db.entity.find({ "SSCEXPEND.2": { "$exists": true } })
It's the fastest way to do it and can even use indexes. No need for calculations in aggregation operations.
I have this db structure
{
"_id": 107,
"standard": {"name": "building",
"item": [{"code": 151001,
"quantity": 10,
"delivered": 8,
"um": "kg" },
{"code": 151001,
"quantity": 20,
"delivered": 6,
"um": "kg" }]
}
}
And i would like to find all the objects that have code:151001 and just show the delivered field.
For example it would show something like this:
{delivered: 8}
{delivered: 6}
So far i got this query, but it does not show exactly what i want:
db.test.find(
{
"standard.item.code": 151001
}
).pretty()
Since your items are in an array, your best approach will be to use the Aggregation Framework for this.
Example code:
db.test.aggregate(
// Find matching documents (could take advantage of an index)
{ $match: {
"standard.item.code" : 151001,
}},
// Unpack the item array into a stream of documents
{ $unwind: "$standard.item" },
// Filter to the items that match the code
{ $match: {
"standard.item.code" : 151001,
}},
// Only show the delivered amounts
{ $project: {
_id: 0,
delivered: "$standard.item.delivered"
}}
)
Results:
{
"result" : [
{
"delivered" : 8
},
{
"delivered" : 6
}
],
"ok" : 1
}
You'll notice there are two $match steps in the aggregation. The first is to match the documents including that item code. After using $unwind on the array, the second $match limits to the items with that code.