Building a dynamic mongo query for meteor - mongodb

I'm building an app that has clickable 'filters'; I'm creating a list of objects(?) that I want to pass to a mongo 'find', so that I can pull out listings if selected attributes match a certain score.
My data is structured like this (a snippet):
name: 'Entry One',
location: {
type: 'Point',
coordinates: [-5.654182,50.045414]
},
dogs: {
score: '1',
when: 'seasonal',
desc: 'Dogs allowed from October to April'
},
lifeguard: {
score: '1',
when: 'seasonal',
desc: 'A lifeguard hut is manned between April and October',
times: ''
},
cafe: {
score: '1',
name:'Lovely cafe',
open:'seasonal'
}, ...
My search variable is a list of objects (I think?) that I assign to a session variable. If I output this session var ('searchString') via JSON.stringify, it looks like this:
{"cafe":{"score":"1"},"dogs":{"score":"1"}}
I'd like to pass this to my mongo find so that it only lists entries that match these scores on these attributes, but it's returning zero results. Do I need to somehow make this an $and query?
Currently it looks like this:
Beaches.find(searchString);
Unfortunately as soon as I drop searchString into the find, I get zero results even if it's empty {}. (When it's just a find() the entries list fine, so the data itself is ok)
What am I doing wrong? I'm relatively new to mongo/meteor, so I apologise in advance if it's something stupidly obvious!

Don't stringify the query. Flatten the object instead. Example:
Beaches.find({
"cafe.score": 1,
"dogs.score": 1,
});

Related

How to target a field in Prisma and get a flat array of values rather than an array of objects

I just started using Primsa 2 so I am still a noob at this but all I am trying to do is create a flat array of strings(Array<number>) based on the values I get from a specific field. Right now when I target that field it gives me an array of objects like this: userIds: [{ issueId: 1, userId: 1 }]
All I want is the value I get from the userId key and the array to return like this userIds: [ 1 ]. I was able to fix this with some formatting code after the query which was done like so:
const issues = project.issues.map(issue => ({ ...issue, userIds: [...issue.userIds.map((id) => id.userId)] }))
const _project = { ...project, issues }
However, this doesn't seem like the most optimal solution. If this is the only way that is fine but I assume with the power that Prisma has for querying, this is something I can do just in the query alone?
For reference, my query currently looks like this:
const project = await prisma.project.findFirst({
where: { id: req.currentUser.projectId },
include: { users: true, issues: { include: { userIds: true } } },
})
Thanks in advance!
Can you show your schema? Perhaps you can model the relation differently. However, unless if you provide a field, userIds, that is a flat array and not a field of a an other relation it will be returned as a list of objects as you have already.

Getting a value from MongoDB using ExpressJS

I'm trying to single fetch a value from my database.
I have a collection named: randoms
Model's Name: Random
Inside the collection, I have one object and with a name field. I want to retrieve that value of 'name' and display it in my console.
The result in the console should be: 'TestName' only.
This has been my approach:
Random.find({}, (err, randoms) => {
if(err) throw err
// console.log(randoms)
res.render('entries', console.log(randoms.name))
})
The console displays the result: undefined.
Here's the database.
If I console.log(randoms) instead of console.log(randoms.name) I get the result:
[{
_id: 5e256c819f972c268493488c,
name: 'TestName',
defination: 'Home page paragraph text',
count: 2,
__v: 0
}]
so that means the connection is alright.
db.collection.find returns a Cursor which is A pointer to the result set of a query. Clients can iterate through a cursor to retrieve results.
yourCollection.find().forEach(function(item){})

return specific properties of array element - MongoDB/ Meteor

I have documents in games collection.Each document is responsible for holding the data that requires to run the game. Here's my document structure
{
_id: 'xxx',
players: [
user:{} // Meteor.users object
hand:[] //array
scores:[]
calls:[]
],
table:[],
status: 'some string'
}
Basically this is a structure of my card game(call-bridge). Now what I want for the publication is that the player will have his hand data in his browser( minimongo ) along with other players user, scores, calls fields. So the subscription that goes down to the browser will be like this.
{
_id: 'xxx',
players: [
{
user:{} // Meteor.users object
hand:[] //array
scores:[]
calls:[]
},
{
user:{} // Meteor.users object
scores:[]
calls:[]
},
// 2 more player's data, similar to 2nd player's data
],
table:[],
status: 'some string'
}
players.user object has an _id property which differentiates the user. and in the meteor publish method, we have access to this.userId which returns the userId who is requesting the data.It means I want the nested hand array of that user whose _id matches with this.userId. I hope this explanations help you write more accurate solution.
What you need to do is "normalize" your collection. Instead of having hand,scores, calls in the players field in the Games collection, what you can do is create a separate collection to hold that data and use the user _id as the "Key" then only reference the user _id in the players field. For example.
Create a GameStats collection(or whichever name you want)
{
_id: '2wiowew',
userId: 1,
hand:[],
scores:[],
calls:[],
}
Then in the Games collection
{
_id: 'xxx',
players: [userId],
table:[],
status: 'some string'
}
So if you want to get the content of the current user requesting the data
GameStats.find({userId: this.userId}).hand
EDIT
They do encourage denormalization in certain situations, but in the code you posted above, array is not going to work. Here is an example from the mongoDB docs.
{
_id: ObjectId("5099803df3f4948bd2f98391"),
name: { first: "Alan", last: "Turing" },
birth: new Date('Jun 23, 1912'),
death: new Date('Jun 07, 1954'),
contribs: [ "Turing machine", "Turing test", "Turingery" ],
views : NumberLong(1250000)
}
To get a specific property from an array element you may write something as in the below line db.games.aggregate([{$unwind:"$players"},{$project:{"players.scores":1}}]); this gives us only the id and scores fields

What exactly is "data" that is passed to responses?

I'm writing a custom response that takes data as an input, and I am finding strange properties being added, namely:
add: [Function: add],
remove: [Function: remove]
When I log out some example data, I get:
[ { books:
[ { id: 1,
title: 'A Game of Thrones',
createdAt: '2015-08-04T04:53:38.043Z',
updatedAt: '2015-08-04T04:53:38.080Z',
author: 1 } ],
id: 1,
name: 'George R. R. Martin',
createdAt: '2015-08-04T04:53:38.040Z',
updatedAt: '2015-08-04T04:53:38.073Z' },
{ books:
[ { id: 2,
title: 'Ender\'s Game',
createdAt: '2015-08-04T04:53:38.043Z',
updatedAt: '2015-08-04T04:53:38.080Z',
author: 2 },
{ id: 3,
title: 'Speaker for the Dead',
createdAt: '2015-08-04T04:53:38.043Z',
updatedAt: '2015-08-04T04:53:38.081Z',
author: 2 } ],
id: 2,
name: 'Orson Scott Card',
createdAt: '2015-08-04T04:53:38.042Z',
updatedAt: '2015-08-04T04:53:38.074Z' } ]
Which looks innocent enough, but results in the strange add and remove functions when I use a custom serializer on it. If I take this data and hard-code it straight into the serializer, those are not present. Apparently something is lurking inside of data that's not being printed to the console.
So, what is data?
Edit: So, I'm still not quite sure what other magical properties live in here, but:
Object.keys(data[0].books))
reveals
[ '0', 'add', 'remove' ]
Which is where those are coming from. Why is this included in the data passed to custom responses? And what else might be hiding in there...
More importantly, how do I strip this gunk out and make data a normal object?
JSON.parse(JSON.stringify(data));
That cleans it up nicely, though it feels like a hack. (Actually, it's definitely a hack.)
I assume your data attribute is returned by a database query. e.g.:
Model.find(...).exec(function (err, data) { ... });
But what are these .add() and .remove() methods?
Here is what you can find in the docs:
For the most part, records are just plain old JavaScript objects (aka POJOs). However they do have a few protected (non-enumerable) methods for formatting their wrapped data, as well as a special method (.save()) for persisting programmatic changes to the database.
We can go deeper:
"collection" associations, on the other hand, do have a couple of special (non-enumerable) methods for associating and disassociating linked records. However, .save() must still be called on the original record in order for changes to be persisted to the database.
orders[1].buyers.add({ name: 'Jon Snow' });
orders[1].save(function (err) { ... });
So these methods (.add(), .remove(), .save()) are useful if you play with "collection" associations.
How to remove them?
You'll need to use .toObject() which returns a cloned model instance stripped of all instance methods.
You might want to use .toJSON() that also returns a cloned model instance. This one however includes all instance methods.

Update values in array in MongoDB

I'm trying to come up with a way to update the values in an array of objects in mongo. I have a collection which looks like
[
{ CourseName: '',
Sessions: [
{
_id: null, //oops I didn't set this in the import
Name: 'blah',
Location: 'moon'
}]
}
]
Now I need to set the _id field. I tried the documented approach of doing
db.Course.update({'Sessions._id': null}, {$set:{'Sessions.$._id': ObjectId()}}, false, true)
But I ran into this bug http://jira.mongodb.org/browse/SERVER-1055 which meant that I couldn't do it. Is there some syntax which will allow me just to itterate over the collection and update each record by hand? I tried a few things like
db.Course.find().forEach(
function(course)
{
course.Sessions.forEach(function(session)
{
session._id=ObjectId();
course.Save(session); //Don't know how to save a single object
});
});
but they didn't work. I'm looking for some way to just update that value in each session.
I think what you want is:
db.Course.find().forEach(
function(course)
{
course.Sessions.forEach(function(session)
{
session._id=ObjectId();
});
db.Course.save(course);
});
However, you can run into problems saving stuff into a collection you're in the middle of iterating over, so I'd suggest loading a bunch of documents into an array, processing them, loading another batch, etc.