I'm trying to do a simple query where some collection data is returned. I want to filter out the _id field in the results.
From my understanding (based on the documentation) the syntax to do so should look like this:
myCollection.findOne(
{ name: hostName },
{ $project: { _id: 0 } }
)
However when I do this the filter has not been applied, e.g.:
{
_id: XXXXXXXXXXXXXXXXXXXX,
name: 'the name',
...
}
Can anybody point me in the right direction?
There are other options for $project. Below one provides the data without _id
myCollection.findOne({ name: hostName }, { '_id': 0 },(err,res)
In case anyone else comes across this, it turns out that the documentation is inaccurate and does not reflect the current state of the SDK.
For reference, see this GitHub Issue where it was confirmed by a Realm dev: https://github.com/realm/realm-js/issues/3275
Related
the problem I am facing is as follows:
Search value: 'cooking'
JSON object::
data: {
skills: {
items: [ { name: 'cooking' }, ... ]
}
}
Expected result: Should find all the "skill items" that contain 'cooking' inside their name, using TypeORM and Nest.js.
The current code does not support search on the backend, and I should implement this. I want to use TypeORM features, rather than handling it with JavaScript.
Current code: (returns data based on the userId)
const allItems = this.dataRepository.find({ where: [{ user: { id: userId } }] })
I investigated the PostgreSQL documentation regarding the PostgreSQL functions and even though I understand how to create a raw SQL query, I am struggling to convert this to the TypeORM equivalent.
Note: I researched many StackOverflow issues before creating this question, but do inform me If I missed the right one. I will be glad to investigate.
Can you help me figure out the way to query this with TypeORM?
UPDATE
Let's consider the simple raw query:
SELECT *
FROM table1 t
WHERE t.data->'skills' #> '{"items":[{ "name": "cooking"}]}';
This query will provide the result for any item within the items array that will match exact name - in this case, "cooking".
That's totally fine, and it can be executed as a raw request but it is certainly not easy to maintain in the future, nor to use pattern matching and wildcards (I couldn't find a solution to do that, If you know how to do it please share!). But, this solution is good enough when you have to work on the exact matches. I'll keep this question updated with the new findings.
use Like in Where clause:
servicePoint = await this.servicePointAddressRepository.find({
where: [{ ...isActive, name: Like("%"+key+"%"), serviceExecutive:{id: userId} },
{ ...isActive, servicePointId: Like("%"+key+"%")},
{ ...isActive, branchCode: Like("%"+key+"%")},
],
skip: (page - 1) * limit,
take: limit,
order: { updatedAt: "DESC" },
relations:["serviceExecutive","address"]
});
This may help you! I'm matching with key here.
I'm setting up a comments-like system where comments have a parent field which relations to another comment. I want to be able to query the top level comment by finding comments that have no parent set, but I cannot see in the documentation any way to do this.
I tried this, but it doesn't look like the $null filter works on joins.
const posts = await strapi.entityService.findMany('api::post.post', {
filters: {
thread: {
id: {
$eq: entity[0].id,
}
},
parent: {
$null: true,
}
}
});
And I get the error: Only $and, $or and $not can by used as root level operators. Found $null.
I can't find anything about this in the Strapi documentation but it seems like a pretty standard thing to do want to do.
So I found a solution to this using the Strapi query API rather than the entity service:
const posts = await strapi.db.query('api::post.post').findMany({
where: {
thread: entity[0].id,
parent: null
}
});
filters[relation_name][id][$null]=true
or
filters:{
relation_name:{
id:{
$null:true
}
}
}
This helped me to filter out the record where a relation is null/doesn't exist.
I have a MongoDB collection called users with documents that look like:
{
_id: ObjectId('123'),
username: "abc",
avatar: "avatar/long-unique-random-string.jpg",
connections: [ObjectId('abc'), ObjectId('xyz'), ObjectId('lmn'), ObjectId('efg')]
}
This document belongs to the users collection.
What I want to do:
First, find one document from the users' collection that matches _id -> '123'.
Project the connections field received from step 1, which is an array of ObjectIds of other users within the same collection.
Find all documents of users from the array field projected in step 2.
Project and return an array of only the username and avatar of all those users from step 3.
While I know that I can do this in two separate queries. First using findOne which returns the friends array. Then, using find with the results of findOne to get all the corresponding usernames and avatars.
But, I would like to do this in one single query, using the aggregation pipeline.
What I want to know, is it even possible to do this in one query using aggregation?
If so, what would the query look like?
What, I currently have:
await usersCollection
.aggregate([
{ $match: { _id: new ObjectId(userId) } },
{ $project: { ids: "$connections" } },
{ $match: { _id: { $in: "ids" } } },
{
$project: {
username: "$username",
avatar: { $ifNull: ["$avatar", "$$REMOVE"] },
},
},
])
.toArray()
I know this is wrong because each aggregation stage receives the results from the previous stage. So, the second match cannot query on the entire users' collection, as far as I know.
I'm using MongoDB drivers for nodeJS. And I would like to avoid $lookup for possible solutions.
I'm transitioning to ArangoDB for its power as a graph database and am struggling with the simple stuff.
If I have a document...
{ _id:'1234', tags:['apple','orange'] }
how can I update it to push or pull a value from the array? I would expect the syntax to be something like this, but didn't find anything in the docs...
collection.update({ _id:'1234' },{ tags:pull('mango') })
collection.update({ _id:'1234' },{ tags:push('avocado') })
Thank you!
You achieve this with AQL. For example
FOR c in collection UPDATE c WITH { tags : PUSH(c.tags, 'avocado')} IN collection
https://docs.arangodb.com/3.3/AQL/Operations/Update.html
How can I query a Mongo collection using Mongoose to find all the documents that have a specific relation between two of their own properties?
For example, how can I query a characters collections to find all those characters that have their currentHitPoints value less than their maximumHitPoints value? Or all those projects that have their currentPledgedMoney less than their pledgeGoal?
I tried to something like this:
mongoose.model('Character')
.find({
player: _currentPlayer
})
.where('status.currentHitpoints').lt('status.maximumHitpoints')
.exec(callback)
but I am getting errors since the lt argument must be a Number. The same goes if I use $.status.maximumHitpoints (I was hoping Mongoose would be able to resolve it like it does when doing collection operations).
Is this something that can be done within a Query? I would expect so, but can't find out how. Otherwise I can filter the whole collection with underscore but I suspect that is going to have a negative impact on performance.
PS: I also tried using similar approaches with the find call, no dice.
MongoDB 3.6 and above supports aggregation expressions within the query language:
db.monthlyBudget.find( { $expr: { $gt: [ "$spent" , "$budget" ] } } )
https://docs.mongodb.com/manual/reference/operator/query/expr/
Thanks to Aniket's suggestion in the question's comments, I found that the same can be done with Mongoose using the following syntax:
mongoose.model('Character')
.find({
player: _currentPlayer
})
.$where('this.status.currentHitpoints < this.status.maximumHitpoints')
.exec(callback)
Notice the $where method is used instead of the where method.
EDIT: To expand on Derick's comment below, a more performance sensitive solution would be to have a boolean property inside your Mongoose schema containing the result of the comparison, and update it everytime the document is saved. This can be easily achieved through the use of Mongoose Schema Plugin, so you would have something like:
var CharacterSchema = new mongoose.Schema({
// ...
status: {
hitpoints: Number,
maxHitpoints: Number,
isInFullHealth: {type: Boolean, default: false}
}
})
.plugin(function(schema, options) {
schema.pre('save', function(next) {
this.status.isInFullHealth = (this.status.hitPoints >= this.status.maxHitpoints);
next();
})
})
mongoose.model('Character')
.find({
player: _currentPlayer, $expr: { $lt: ['$currentHitpoints', '$maximumHitpoints'] }
})
This above query means find the record which has currentHitpoints less than maximumHitpoints
Starting in MongoDB 5.0, the $eq, $lt, $lte, $gt, and $gte comparison operators placed in an $expr operator can use an index on the from collection referenced in a $lookup stage.
Example
The following operation uses $expr to find documents where the spent amount exceeds the budget:
db.monthlyBudget.find( { $expr: { $gt: [ "$spent" , "$budget" ] } } )