so I have this system where users can input tags, but i want to add suggestions/auto-complete with dynamic data from all the previous tags in the database.
Here's what the data looks like:
collection = [
{
title: "Avengers",
tags:["si-fi", "powers", "super-heroes", "iron-man"],
...
},
{
title: "Lego Movie"
tags:["spider-man", "bottle", "man of steel"],
...
}
...
]
So I want to retreive an array of all the tags that match a search string.
For example, if I search with 'man', I want the data returned to be:
[
"iron-man",
"spider-man",
"man of steel"
]
I think it cannot be done by direct querying. The following aggregation can do,
db.collection.aggregate([{
$unwind: '$tags'
}, {
$match: {
'tags': { $regex: 'man' }
}
}, {
$group: {
_id: null,
tags: { '$addToSet': '$tags' }
}
}]);
Hope this helps!
Related
I need to find and update documents with category that corresponding to the query. Array could contain mo than one corresponding id.
Query:
{
"ids": ["61f1cda47018c60012b3dd01", "61f1cdb87018c60012b3dd07"],
"userId": "61eab3e57018c60012b3db3f"
}
I got collection with documents like:
`{
"_id":{"$oid":"61f1cdd07018c60012b3dd09"},
"expenses":[
{"category":"61eafc104b88e154caa58616","price":"1111.00"},
{"category":"61f1cdb87018c60012b3dd07","price":"2222.00"},
{"category":"61f1cda47018c60012b3dd01","price":"1241.00"},
{"category":"61f1cdb87018c60012b3dd07","price":"111.00"}
],
"userId":"61eab3e57018c60012b3db3f"
}`
my method:
async myMethod(ids: [string], userId: string) {
try {
const { ok } = await this.ExpensesModel.updateMany(
{"userId": userId, "expenses.category": { $in: ids }},
{$set: {"expenses.$.category": "newCategoryID"}}
);
return ok
} ........
I path array of ids ["61f1cda47018c60012b3dd01","61f1cdb87018c60012b3dd07","61f1cdb87018c60012b3dd07"] and userId, this code update only 1 category by document.
So can i made it with mongo build in methods? or i need to find matching document and update it it by my self and after that update or insert;
Update with arrayFilters
db.collection.update({
"expenses.category": {
$in: [
"61f1cda47018c60012b3dd01",
"61f1cdb87018c60012b3dd07"
]
}
},
{
$set: {
"expenses.$[elem].category": "61eab3e57018c60012b3db3f"
}
},
{
arrayFilters: [
{
"elem.category": {
$in: [
"61f1cda47018c60012b3dd01",
"61f1cdb87018c60012b3dd07"
]
}
}
]
})
mongoplayground
I have a collection of mongodb like this :
[{
"_id":"ObjectId(""51780fb5c9c41825e3e21fc4"")",
"name":"CS 101",
"students":[
{
"name":"raj",
"year":2016
},
{
"name":"rahul",
"year":2017
},
{
"name":"anil",
"year":2018
}
]
},
{
"_id":"ObjectId(""51780fb5c9c41825e3e21fs4"")",
"name":"CS 102",
"students":[
{
"name":"mukesh",
"year":2016
},
{
"name":"mohan",
"year":2017
},
{
"name":"mangal",
"year":2018
}
]
}
]
I've been looking for similar questions like this one: Mongo db - Querying nested array and objects but in that question they're looking for a specific element inside the "messages" object (in my case) for example. Same as in this other question: Query for a field in an object in an array with Mongo? where they're using $mapan d I don't think it fits my needs.
The documents to find have this structure:
[{
"_id":"ObjectId(""51780fb5c9c41825e3e21fc4"")",
"name":"CS 101",
"students":[
"raj","rahul","anil"
]
},
{
"_id":"ObjectId(""51780fb5c9c41825e3e21fs4"")",
"name":"CS 102",
"students":[
"mukesh","mohan","mangal"
]
}
]
how to solve this?
From the question and datasets, you are trying to return students with an array of student's name (string) instead of the array of student object.
Use $project to display students as students.name array.
db.collection.aggregate([
{
$project: {
"_id": "$_id",
"name": "$name",
"students": "$students.name"
}
}
])
Sample Solution 1 on Mongo Playground
OR
Use $set to replace the students field with students.name array.
db.collection.aggregate([
{
$set: {
"students": "$students.name"
}
}
])
Sample Solution 2 on Mongo Playground
I'd like to do a search in MongoDB using either Mongo or Mongoose based on the value of a field in a document.
Let's say I had three MongoDB documents that looked like this:
{
name: "Michael",
mentored: ["Dwight", "Ryan", "Jim"]
},
{
name: "Jim",
mentored: ["Toby", "Roy", "Darryl"]
},
{
name: "Stanley",
mentored: ["Pam", "Meredith", "Angela"]
}
Let's further say I want to do a search for anyone who Michael has not mentored, which in this case would be Stanley (let's assume that the people in the arrays don't necessarily have their own records). I know I can do a search like this in Mongoose to get the result I want:
User.findOne({ name: "Michael" })
.then((person) => {
const mentored = person.mentored
return User.find({ name: { $nin: mentored } })
)
.then((person2) => {
console.log(person2); // Stanley
})
However, is there any way to do this without first returning the array from the database and then doing a second search? Something like this:
User.findOne({ name: { $nin: { "Michael's mentored people array" } } })
Ultimately I'm looking to see if there's any way to make more efficient such a situation in which arrays can get 10s of thousands of values long. Many thanks.
I think what you are doing is already efficient for large arrays.
But you could try the following, as suggested by #D.SM. but using aggregation the intermediate results will have to be loaded in memory, which does not seem efficient to me.
User.aggregate([
{
$match: {
name: "Michael"
}
},
{
$lookup: {
from: "collection",
as: "notMentored",
let: {
mentored: "$mentored",
/*
You probably want to remove "Michael" from the result, one way is to add him to the mentored array
mentored: { $concatArrays: ["$mentored", ["$name"]]}
*/
},
pipeline: [{
$match: {
$expr: { $not: { $in: ["$name", "$$mentored"] } }
}
}]
}
},
{
$unwind: "$notMentored"
},
{
$replaceRoot: {
newRoot: "$notMentored"
}
}
])
I have the following query:
Documents.find({
$and: [
{
user_id: {$nin:
myUserId
}
},
{ date: { $gte: dateMax, $lt: dateMin } },
{documentTags: {$all: tags}}
],
})
What I'm trying to do is make the documentTags portion of the query optional. I have tried building the query as follows:
let tags = " ";
if (req.body.tags) {
tags = {videoTags: {$all: req.body.tags}};
}
let query = {
$and: [
{
user_id: {$nin:
myUserId
}
},
{ date: { $gte: dateMax, $lt: dateMin } },
tags
],
}
and then Document.find(query). The problem is no matter how I modify tags (whether undefined, as whitespace, or otherwise) I get various errors like $or/$and/$nor entries need to be full objects and TypeError: Cannot read property 'hasOwnProperty' of undefined.
Is there a way to build an optional requirement into the query?
I tried the option below and the query is just returning everything that matches the other fields. For some reason it isn't filtering by tags. I did a console.log(queryArr) and console.log(query) get the following respectively:
[
{ user_id: { '$nin': [Array] } },
{
date: {
'$gte': 1985-01-01T00:00:00.000Z,
'$lt': 2020-01-01T00:00:00.000Z
}
},
push: { documentTags: { '$all': [Array] } }
]
console.log(query)
{
'$and': [
{ user_id: [Object] },
{ date: [Object] },
push: { documentTags: [Object] }
]
}
You are almost there. Instead you could construct the object outside the query and just put the constructed query in $and when done..
let queryArr = [
{
user_id: {$nin: myUserId}
},
{ date: { $gte: dateMax, $lt: dateMin } }
];
if (req.body.tags) {
queryArr.push({videoTags: {$all: req.body.tags}});
}
let query = {
$and: queryArr
}
Now you can control the query by just pushing object into the query Array itself.
I figured out why it wasn't working. Basically, when you do myVar.push it creates a key-value pair such as [1,2,3,push:value]. This would work if you needed to append a k-v pair in that format, but you'll have difficulty using it in a query like mine. The right way for me turned out to be to use concact which appends the array with just the value that you set, rather than a k-v pair.
if (req.body.tags){
queryArgs = queryArgs.concat({documentTags: {$all: tags}});
}
let query = {
$and: queryArgs
}
I currently have a problem where I have to update entries in a deeply nested Document. Now to simplify my problem I have this example. Let's assume I store cars in my MongoDB. A Document would look like this
{
Make: "BMW",
Model: "3Series",
Wheels: [
{
_id: someObjectId
Size: "19 inch",
Screws: [
{
_id: someObjectId
Type : "M15x40"
},
{
_id: someObjectId
Type : "M15x40"
}
]
}
]
}
Now if I want to update a specific Wheel, my code would look somewhat like this
CarModel.findOneAndUpdate({
"_id": CarId, "Wheels._id": WheelId
}, {
"$set" : {
"Wheels.$.Size": NewSize
}
})
Now this works. But I am pretty lost on how I would update an specific screw as I am going through 2 Arrays. Any Idea how I could make this work?
You need arrayFilters functionality to define the path for more than one nested array:
CarModel.findOneAndUpdate(
{ "_id": CarId },
{ $set: { "Wheels.$[wheel].Screws.$[screw].Type": "something" } },
{ arrayFilters: [ { 'wheel._id': WheelId }, { 'screw._id': screwId } ] })