How to Query a nested child from firebase angular? - javascript

// my db structure now
rcv : {
visible: 'all',
ids: [
[0] : userId,
[1] : user2Id ]
}
this is how i query to get the data it works.
//service.ts
getAlbumByUserId(userId) {
return this.afs.collection('albums', ref => ref.where('rcv.visible', '==', 'all').where('rcv.ids', 'array-contains', userId)).valueChanges();
}
//component.ts
this.service.getAlbumByUserId(this.userId);
but i want to set the structure like this but i don't know how to query nested objects in firebase
// database structure
rcv : {
visible: 'all',
ids: {
userId: {
id: userId
}
user2Id: {
id: user2Id
}
}
}

You're looking for the array-contains operator, which can check if a field that is an array contains a certain value.
You're already using the correct array-contains operator, but not with the correct syntax. The array-contains operator checks whether any element of your array is exactly the same as the value you pass in. So you need to pass in the complete value that exists in the array:
ref.where('rcv.visible', '==', 'all').where('rcv.ids', 'array-contains', { id: userId })
As you add more data to the array, it may become unfeasible to reproduce the entire array element for the query. In that case, the common approach is to add an additional field where you keep just the IDs.
So you'd end up with one field (say rcv.users) where you keep all details about the receiving users, and one field (say rcv.ids) where you just keep their IDs, and that you use for querying.

Related

Prisma - Optimistic Update using LastUpdated field, is it possible to express with Prisma's safe query builder syntax?

I am working with a PostgreSQL database using Prisma. I have a bulk update command which I want to fail if any of the records have changed since my last read.
My schema:
model OrderItem {
id String #id #default(uuid()) #db.Uuid
quantity Int
lastUpdated DateTime #updatedAt #map("last_updated")
##map("order_item")
}
I have written a query which works, but I built the query manually rather than using Prisma's safe query builder tools.
My query:
type OrderItemType = {
id: string;
quantity: number;
lastUpdated: Date;
}
type OrderItemUpdateDataType = {
quantity: number;
}
const updateByIds = async (
orderItemIdLastUpdatedTuples: ([OrderItemType['id'], OrderItemType['lastUpdated']])[],
orderItemUpdateData: OrderItemUpdateDataType,
) => {
// Optimistic concurrency - try updating based on last known "last updated" state. If mismatch, fail.
await prisma.$transaction(async (prisma) => {
// TODO: Prefer prisma.$queryRaw. Prisma.join() works on id[], but not on [id, lastUpdated][]
const idLastUpdatedPairs = orderItemIdLastUpdatedTuples
.map(([id, lastUpdated]) => `(uuid('${id}'), '${lastUpdated.toISOString()}')`)
.join(', ');
const query = `SELECT * FROM order_item WHERE (id, last_updated) in ( ${idLastUpdatedPairs} )`;
const items = await prisma.$queryRawUnsafe<OrderItem[]>(query);
// If query doesn't match expected update count then another query has outraced and updated since last read.
const itemIds = orderItemIdLastUpdatedTuples.map(([id]) => id);
if (items.length !== orderItemIdLastUpdatedTuples.length) {
throw new ConcurrentUpdateError(`Order Items ${itemIds.join(', ')} were stale. Failed to update.`);
}
await prisma.orderItem.updateMany({
where: { id: { in: itemIds } },
data: orderItemUpdateData,
});
});
};
This function wants to update a set of items. It accepts a list of tuples - id/lastUpdated pairs. It starts an explicit transaction, then performs an unsafe SELECT query to confirm the items to affect haven't been updated, then updates. This is following the guidance of Prisma's docs here - https://www.prisma.io/docs/concepts/components/prisma-client/transactions#interactive-transactions-in-preview
I was hoping to achieve the same results using prisma.$queryRaw rather than prisma.$queryRawUnsafe or even using implicit transactions rather than an explicit transaction wrapper. I wasn't able to find a syntax for expressing "where in tuple" using either of these approaches, though.
I am able to express what I want using implicit transactions when updating a single record. An example here would look like:
const { count } = await prisma.orderItem.updateMany({
where: { id, lastUpdated },
data: orderItemUpdateData,
});
and when using an explicit, safe query I stumbled on joining the array of tuples properly.
From the Prisma documentation, https://www.prisma.io/docs/concepts/components/prisma-client/raw-database-access#tagged-template-helpers, there exists a Prisma.join command (which happens implicitly when using their tagged template helper syntax) but I wasn't able to generate a valid output when feeding it an array of tuples.
Did I miss anything? Does Prisma support joining a tuple using their safe query template syntax?

How to update a document based on two filter conditions?

I have a document structure that looks like this:
type Document = {
_id: string
title: string
variants: VariantType[]
}
type VariantType = {
timestamp: Int
active: Boolean
content: any[]
}
I'm trying to filter a document based on two filter conditions in one query. First I want to match the _id and then find a specific variant based on a timestamp.
My previous version of the query was filtering based on the active key.
const updatedDocument = await allDocuments
.findOneAndUpdate({ _id: mongoId, 'variants.active': false }, .... };
Changing it to
const updatedDocument = await allDocuments
.findOneAndUpdate({ _id: mongoId, 'variants.timestamp': timestamp }, .... };
returns null.
Can mongo even match a document like this. I saw that there is an $eq query selector but I can't seem to get it working either.
Turns out I the problem was with the timestamp I was sending to the server. I was getting it from the wrong place and it wasn't matching any of the variants.

Insert documents into collection unless they are already inserted?

I get a list of objects from an API:
let sold = [
{ objId: 3240747,
soldDate: '2018-09-27',
soldPrice: 4610000,
apartmentNumber: '1202',
soldPriceSource: 'bid',
},
{ objId: 3234263,
soldDate: '2018-09-24',
soldPrice: 2580000,
soldPriceSource: 'bid',
}
...
]
I store these in a collection:
soldCollection.insertMany(sold)
Some of the objects have been retrieved before, and I only want to store the once that are not already in the database.
dbo.collection("sold").createIndex({ "objId": 1 }, { unique: true })
What would be an efficient way of doing this? Should I ask for each object before storing it or is there method for dealing with this?
By default insertMany will stop inserting when first error occurs (E11000 duplicate key error in this case). You can change that behavior by specifying ordered parameter set to false. In that case you'll get a list of errors from failed inserts however all valid documents will be inserted succesfully:
db.sold.insertMany(sold, { ordered: false })
docs example here

Mongoose: Add more items to existing object

Using Mongoose, How can I add more items to an object without replacing existing ones?
User.findOneAndUpdate(
{ userId: 0 },
{ userObjects: { newItem: value } }
);
The problem with above code is that it clears whatever was there before and replaces it with newItem when I wanted it just to add another item to userObjects(Like push function for javascript arrays).
Use dot notation to specify the field to update/add particular fields in an embedded document.
User.findOneAndUpdate(
{ userId: 0 },
{ "userObjects.newerItem": newervalue } }
);
or
User.findOneAndUpdate(
{ userId: 0 },
{ "$set":{"userObjects.newerItem": newervalue } }
);
or Use $mergeObjects aggregation operator to update the existing obj by passing new objects
User.findOneAndUpdate(
{"userId":0},
[{"$set":{
"userObjects":{
"$mergeObjects":[
"$userObjects",
{"newerItem":"newervalue","newestItem":"newestvalue"}
]
}
}}]
)
According to your question, i am guessing userObjects is an array.
You can try $push to insert items into the array.
User.findOneAndUpdate(
{ userId: 0 },
{ $push : {"userObjects": { newItem: value } }},
{safe :true , upsert : true},function(err,model)
{
...
});
For more info, read MongoDB $push reference.
Hope it helps you. If you had provided the schema, i could have helped better.
Just create new collection called UserObjects and do something like this.
UserObject.Insert({ userId: 0, newItem: value }, function(err,newObject){
});
Whenever you want to get these user objects from a user then you can do it using monogoose's query population to populate parent objects with related data in other collections. If not, then your best bet is to just make the userObjects an array.

Mongodb: Find ids $in nested array property

I have the following data structure for my users in my mongodb:
{
_id: "someId",
profile: {
username: "oliv",
friendRequests: [
{ fromUserId: "anId", accepted: false, created: "someDate"},
{ fromUserId: "otherId", accepted: true, created: "otherDate"}
]
}
I'd like to retrieve the user objects that are referenced in my logged user's friendsRequested.
So I tried something like this:
Meteor.users.find({_id: {$in: Meteor.user().profile.friendRequests.fromUserId}});
// FYI: Meteor.users is the collection and Meteor.user() retrieves the current user
But it's not working. I'm assuming it's because of the nested array.
Is there any way of telling mongo to iterate through the fromUserId or something?
Thanks
Change your query to:
Meteor.users.find({_id: {$in: _.pluck(Meteor.user().profile.friendRequests, 'fromUserId') }});
Reasoning:
friendRequests is an array of objects, and $in wants an array of strings(the ids), using _.pluck you're able to pass an array of objects, and tell _ to only return the field fromUserId for each object in the array.
Question in comment ("what if I only want to get the ids from friend requests where "accepted" is false?"):
_.pluck(
_.filter(Meteor.user().profile.friendRequests, function (req) {
return !req.accepted;
}),
'fromUserid'
);
Underscore filter docs

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