Lets say that I have the following document in the books collection:
{
_id:0 ,
item: "TBD",
stock: 0,
info: { publisher: "1111", pages: 430 },
tags: [ "technology", "computer" ],
ratings: [ { _id:id1, by: "ijk", rating: 4 }, {_id:id2 by: "lmn", rating: 5 } ],
reorder: false
}
I would like to update the value of ratings[k].rating and all I know is the id of the collection and the _id of the objects existing in the array ratings.
The tutorial of mongoDB has the following example that uses the position of the object inside the array but I suppose that if the update can only be done by knowing the position, this means that I firstly have to find the position and then proceed with the update? Can I do the update with only one call and if so how I can do that?
db.books.update(
{ _id: 1 },
{
$inc: { stock: 5 },
$set: {
item: "ABC123",
"info.publisher": "2222",
tags: [ "software" ],
"ratings.1": { by: "xyz", rating: 3 }
}
}
)
Sorry for late answer; I think this is what you want to do with mongoose.
Books.findOneAndUpdate({
_id: 1,
'ratings._id': id1
},
{
$set: {
'ratings.$.rating' : 3
}
}, function(err, book){
// Response
});
Positional operator may help you:
db.books.update(
// find book by `book_id` with `rating_id` specified
{ "_id": book_id, "ratings._id": rating_id },
// set new `value` for that rating
{ $set: { 'ratings.$.rating': value }}
);
$ will save position of matched document.
Related
I have a database of a the employees of a company that looks like this:
{
_id: 7698,
name: 'Blake',
job: 'manager',
manager: 7839,
hired: ISODate("1981-05-01T00:00:00.000Z"),
salary: 2850,
department: {name: 'Sales', location: 'Chicago'},
missions: [
{company: 'Mac Donald', location: 'Chicago'},
{company: 'IBM', location: 'Chicago'}
]
}
I have an exercise in which I need to write the MongoDb command that returns all them employees who did all their missions in Chicago. I struggle with the all because I cannot find a way to check that all the locations of the missions array are equal to 'Chicago'.
I was thinking about doing it in two time: first find the total number of missions the employee has and then compare it to the number of mission he has in Chicago (that how I would do in SQL I guess). But I cannot found the number of mission the employee did in Chicago. Here is what I tried:
db.employees.aggregate([
{
$match: { "missions": { $exists: true } }
},
{
$project: {
name: 1,
nbMissionsChicago: {
$sum: {
$cond: [
{
$eq: [{
$getField: {
field: { $literal: "$location" },
input: "$missions"
}
}, "Chicago"]
}, 1, 0
]
}
}
}
}
])
Here is the result :
{ _id: 7698, name: 'Blake', nbMissionsChicago: 0 }
{ _id: 7782, name: 'Clark', nbMissionsChicago: 0 }
{ _id: 8000, name: 'Smith', nbMissionsChicago: 0 }
{ _id: 7902, name: 'Ford', nbMissionsChicago: 0 }
{ _id: 7499, name: 'Allen', nbMissionsChicago: 0 }
{ _id: 7654, name: 'Martin', nbMissionsChicago: 0 }
{ _id: 7900, name: 'James', nbMissionsChicago: 0 }
{ _id: 7369, name: 'Smith', nbMissionsChicago: 0 }
First of all, is there a better method to check that all the locations of the missions array respect the condition? And why does this commands returns only 0 ?
Thanks!
If all you need is the agents who had all their missions in "Chicago" then you don't need an aggregation pipeline for it, specifically the approach of filtering the array as part of the aggregation can't utilize an index and will make performance even worse.
A simple query should suffice here:
db.collection.find({
$and: [
{
"missions": {
$exists: true
}
},
{
"missions.location": {
$not: {
$gt: "Chicago"
}
}
},
{
"missions.location": {
$not: {
$lt: "Chicago"
}
}
}
]
})
Mongo Playground
This way we can build an index on the missions field and utilize it properly, any documents with a different value other then "Chigaco" will not match as they will fail the $gt or $lt comparion.
Note that an empty array also matches the condition, you can change the generic "missions" exists condition key into "missions.0": {$exists: true}, this will also require at least one mission.
You are unable to get the correct result as it is not the correct way to iterate the element in an array field.
Instead, you need to work with $size operator to get the size of an array and the $filter operator to filter the document.
Updated: You can directly compare the filtered array with the original array.
db.employees.aggregate([
{
$match: {
"missions": {
$exists: true
}
}
},
{
$project: {
name: 1,
nbMissionsChicago: {
$eq: [
{
$filter: {
input: "$missions",
cond: {
$eq: [
"$$this.location",
"Chicago"
]
}
}
},
"$missions"
]
}
}
}
])
Demo # Mongo Playground
This question already has answers here:
Find duplicate records in MongoDB
(10 answers)
Closed 2 years ago.
I have a DB with news articles, and I am trying to do a little DB cleaning. I want to find all duplicate documents, and the best way i think to accomplish this by using the url field. My documents are structured as follows:
{
_id:
author:
title:
description:
url:
urlToImage:
publishedAt:
content:
summarization:
source_id:
}
Any help is greatly appreciated
Assuming a collection documents with name (using name instead of url) field consisting duplicate values. I have two aggregations which return some output which can be used to do further processing. I hope you will find this useful.
{ _id: 1, name: "jack" },
{ _id: 2, name: "john" },
{ _id: 3, name: "jim" },
{ _id: 4, name: "john" }
{ _id: 5, name: "john" },
{ _id: 6, name: "jim" }
Note that "john" has 3 occurrances and "jim" has 2.
(1) This aggregation returns the names which have duplicates (more than one occurance):
db.collection.aggregate( [
{
$group: {
_id: "$name",
count: { $sum: 1 }
}
},
{
$group: {
_id: "duplicate_names",
names: { $push: { $cond: [ { $gt: [ "$count", 1 ] }, "$_id", "$DUMMY" ] } }
}
}
] )
The output:
{ "_id" : "duplicate_names", "names" : [ "john", "jim" ] }
(2) The following aggregation just returns the _id field values for the duplicate documents. For example, the name "jim" has _idvalues 3 and 6. The output has only the id's for the duplicate documents, i.e., 6.
db.colection.aggregate( [
{
$group: {
_id: "$name",
count: { $sum: 1 },
ids: { $push: "$_id" }
}
},
{
$group: {
_id: "duplicate_ids",
ids: { $push: { $slice: [ "$ids", 1, 9999 ] } }
}
},
{
$project: {
ids: {
$reduce: {
input: "$ids",
initialValue: [ ],
in: { $concatArrays: [ "$$this", "$$value" ] }
}
}
}
}
] )
The output:
{ "_id" : duplicate_ids", "ids" : [ 6, 4, 5 ] }
I have an object that has an array of page objects and each page object has an array of questions.
Ex object:
{
Id: 1,
UserId: 14,
Deleted: false,
Collaborators: [],
Title: "Awesome",
Pages: [{
Id: 1,
Title: 'Jank',
Questions: [
{ Id: 1, Content: 'Ask me about it' },
{ Id: 2, Content: 'Ask me about it again' }
]
}, {
Id: 2,
Title: 'Janker',
Questions: [
{ Id: 1, Content: 'Tell me about it' },
{ Id: 2, Content: 'Tell me about it again' }
]
}]
}
What I am trying to do is to get a count of all the questions for the entire bas object. I am not sure how to do that. I have tried to use aggregate and $sum the total questions and then do another function to $sum those all together to get a total for the entire object. Unfortunately my $sum is not working like I thought it would.
Ex code (nodejs):
var getQuestionCount = function(id) {
var cursor = mongo.collection('surveys').aggregate([{
$match: {
$or: [{
"UserId": id
}, {
"Collaborators": {
$in: [id]
}
}]
}
}, {
$match: {
"Deleted": false
}
}, {
$unwind: "$Pages"
},
{ $group: { _id: null, number: { $sum: "$Pages.Questions" } } }
], function(err, result) {
//This log just gives me [object Object], [object Object]
console.log('q count ' + result);
});
}
Any idea how to do this? My end result from the example object above would ideally return 4 as the question count for the whole object.
I'd try following shell query.
db.collection.aggregate([
// filter out unwanted documents.
{$match:{Id: 1}},
// Unwind Pages collection to access Questions array
{$unwind:"$Pages"},
// Count items in Questions array
{$project:{count: {$size:"$Pages.Questions"}}},
// Finally sum items previously counted.
{$group:{_id:"$_id", total: {$sum: "$count"}}}
])
Based on your sample document, it should return correct count of Questions.
{
"_id" : ObjectId("57723bb8c10c41c41ff4897c"),
"total" : NumberInt(4)
}
I have the following schema into my DB:
{ name: 'AFG',
documents: [
{ name: 'doc1',
templates: [
{ name: 'templ1',
lastModified: <Date>},
...]
},
...]
}
I am trying to make a query to look for the template with name 'templ1'. If I find it, I have to compare the last modification date with another and update the value. If I don't find it, I have to push it into the array.
I have tried to do it with the following query:
Country.findOne({name : countrySelected, documents : {$elemMatch: {name: documentSelected}}, 'documents.templates' : {$elemMatch: {name: templateSelected}}}, function(err, templateFound){...}
But I get the following error:
MongoError: cannot use the part (documents of documents.templates) to traverse the element ({documents: [ { name: "Passport", templates: [] }, { name: "Visa", templates: [] }, { name: "Driver's Licence", templates: [] }, { name: "Id Card", templates: [] }, { name: "Other", templates: [] } ]})
Someone knows how can I do it? Thanks!!
You have to use the $in operator to search in arrays.
Country.findOne({
name : countrySelected,
documents: {
$elemMatch: {
$and: [{
name: {
$in: documentSelected //<-- must be array like ['doc1']
}
}, {
'templates.name': {
$in: documentSelected //<-- must be array like ['tmpl1']
}
}]
}
}
}, function(err, templateFound){
//do something with err and templateFound
});
To update the LastModified date you need to update it in the callback function and save the document.
See this answer for nested array updates
I have a Model in MongoDB which include an array(category) which has an array(picture) inside it.
Shirt Model looks like this:
{ _id: 100, category: [ { name: 'CatName', _id: 101, picture: [Object] } ] }
And my Picture Array looks like this:
[ { path: 'p1', _id: 102 },
{ path: 'p2', _id: 103 } ] }
I Pass 3 variables
main array id which is 100 (var1)
category name which is CatName (var2)
picture id which is 102 (var3)
I want to GET an array which looks like:
{ _id: 100, category: [ { name: 'CatName', _id: 101,
picture: [ { path: 'p1', _id: 102 }]
} ]
}
What I have tried is this:
Shirt.find( {_id: var1} ,
{category: { $and:[ { name: var2 } , { picture: {$elemMatch: {_id: var3}}} ] }} )
.exec(function(err, product) {
console.log('Result ' + product );
res.jsonp(product);
});
But the Result I receive is Undefined for First Code
Second Code That I tried:
Shirt.find( {_id: var1} ,
{category: {$elemMatch: { name: var2,picture: {$elemMatch: {_id: var3} }}} } )
And Result from second code filter the array for var1 and var2
But it contain the whole picture array which means it does not filter var3
What is the correct code to find what I want?
Is this a correct approach for a Shopping Website database Or you have a better suggestion?
Am I applying Parent and Child Database Correctly?
Thanks!
Following mongo query will give you expected result:
db.collection.find({
"category": {
$elemMatch: {
"name": "CatName",
"picture": {
$elemMatch: {
"_id": 102
}
}
}
}
})
You need to convert it in node.js format.
Following format may help you. Not Tested
collection.find({
_id: "" // add your match Id here} ,
{
category: {
"$elemMatch": {
"name": "CatName",
"picture": {
$elemMatch: {
"_id": 102
}
}
}
}
}
})
.exec(function(err, product) {
console.log('Result ' + product);
res.jsonp(product);
});
AFTER EDIT QUESTION
You should use mongo aggregation to get required values. Query will be like following -
db.collection.aggregate({
$unwind: '$category'
}, {
$unwind: '$category.picture'
}, {
$match: {
_id: 100, // add here your var1 variable instead of 100
'category.name': 'CatName', // add here your var2 variable instead of 'CatName'
'category._id': 102, //add your match id here if any otherwise remove this condition
'category.picture._id': 102 //add your var3 instead of 102
}
}, {
$group: {
_id: '$category.name',
'name': {
$first: '$category.name'
},
'picture': {
'$push': '$category.picture'
}
}
})