I have searched for join two collection in MongoDB. I found populate. But it is not working for my scenario. I am using mongoose in node js. My schema are like below.
const CoordinateSchema = new mongoose.Schema({
activationId: {
type: mongoose.Schema.ObjectId,
ref: 'Activation'
},
mac: {
type: mongoose.SchemaTypes.String,
required: true,
set: toLower
},
t: { type: Date },
userId: {
type: mongoose.Schema.ObjectId,
ref: 'User'
}
});
const UserSchema = new mongoose.Schema({
email: {
type: mongoose.SchemaTypes.String,
required: true,
//unique: true,
set: toLower
},
mac: {
type: mongoose.SchemaTypes.String,
required: true,
unique: true,
set: toLower,
index: true
},
dob: {
type: mongoose.SchemaTypes.Date,
},
gender: { type: mongoose.SchemaTypes.String, set: toLower },
activations: [{
activationId: {
type: mongoose.Schema.ObjectId,
ref: 'Activation'
},
userType: { type: mongoose.SchemaTypes.String, set: toLower },
_id: false
}]
}
i have thousands of records for single activation in coordinates collection.
My query query requires to filter distinct mac from coordinates collection which matches userType in user collection.
If i use populate method & then apply filter on that it won't restrict fetching record count because of it query is taking so much time because it will return thousands of records.
I want to fetch only coordinates which match userType in user collection.
So far i haven't found any efficient method to join two collection & apply where condition on it.
I want to know efficient method to join two collection in mongodb & apply where condition on both collections.
Related
const user_schema = mongoose.Schema(
{
user_name: {
type: String,
required: true,
},
},
{
collection: `user`,
timestamps: true,
}
);
const test_schema = mongoose.Schema(
{
test_name: {
type: String,
required: true,
},
},
{
collection: `test`,
timestamps: true,
}
);
const score_schema = mongoose.Schema(
{
user_id: {
type: mongoose.Schema.Types.ObjectId,
ref: "user",
required: true,
},
test_id: {
type: mongoose.Schema.Types.ObjectId,
ref: "test",
required: true,
},
test_score: {
type: Number,
required: true,
},
},
{
collection: `score`,
timestamps: true,
}
);
query:
Given an array of user_id and an array of test_id, query the score model to find out the test scores.
To get the array of user_id, a set of conditions is given and the user model must be queried to find the set of users matching the conditions.
To get the array of test_id, a set of conditions is given and the test model must be queried to find the set of tests matching the conditions.
What needs to be done:
Make one query request to the MongoDB server to get the array of user_id.
Make a separate query request to the MongoDB server to get the array of test_id.
Make another query request to the MongoDB server to get the test scores:
db.getCollection("score").aggregate([
{$match: {$and: {user_id: {$in: array_of_user_id}, {test_id: {$in: array_of_test_id}}}}}
])
Is this the most optimal way to get the test scores? Is it possible to make just one request to the MongoDB server?
I have a user schema. While saving document, for every nested object (quizHistory,record & responses) in document, mongoose add _id field automatically. For ref- quizHistory path
const userSchema = new Schema({
firstName: { type: String, required: true ,trim:true},
lastName:{ type: String, required: true ,trim:true},
email: { type: String, unique: true, required: true },
isUser: { type: Boolean, default: true },
password: String,
quizHistory: [{
quizId: { type: Schema.Types.ObjectId, ref: 'Quiz' },
record: [{
recordId:{ type: Number},
startTime: { type: Date },
responses: [{
quesId: { type: Schema.Types.ObjectId, ref: 'Question' },
answers: [Number]
}],
score: Number
}],
avgScore: Number
}]
})
Mongoose create virtual id by default(guide id).
Add this line to your schema.
_id : {id:false}
I created a simple dynamic fields in React-Redux with a plus button to add as many field as I want (hobbies) of an already existing form. I'm using mongodb as a database and so I have this error that tells me that my fields/data don't have iDs.
so how can I generate iDs for my data?
this below is my model with featherJs. as you can see this is how I added my hobbies array in the existing model called myService. I can see that my hobbies are created in mongo (using Robo 3T) which is great but i'm having difficulty reusing them (hobbies) in an other component in Redux. I'm not sure if I should give IDs to this fields or create a new service just for them. I never coded something in backend so I'm confused. what's the rule for this kind of situations.
Any other suggestions would be helpful.
warning in Redux: Each child in a list should have a unique "key" prop.
error in api : Cast to ObjectId failed for value at path "_id" for model "
const { Schema } = mongooseClient;
const myService = new Schema({
type: { type: String, enum: VALID_TYPES, required: true },
user: {
type: mongooseClient.Schema.Types.ObjectId,
ref: 'user',
required: true
},
comment: String,
hobbies: [{
type: mongooseClient.Schema.Types.ObjectId,
ref: 'hobbies',
default: [],
required: false }],
date: {
begin: { type: Date, default: Date.now },
current: { type: Date, default: Date.now },
end: { type: Date, required: true },
},
}, {
timestamps: true
});
return mongooseClient.model('myService', myService);
};
I have 2 mongoose schemas, one for stock (info about stock) and one for trade. Where trade represents the trades of a stock (so time, volume, etc). Each stock has a symbol code and the data feed that I get the trades from includes the symbol codes as strings. How would I populate these two collections since I can't use the regular mongoose 'ref' here.
Here are my two schemas:
const stockSchema = new Schema({
symbolCode: { type: String, trim: true },
symbol: { type: String, trim: true },
type: { type: String, index: true, trim: true },
country: { type: String, lowercase: true }
})
const tradeSchema = new Schema({
symbolCode: { type: String, index: true },
symbol: { type: String, index: true },
price: Number,
volume: Number,
time: Date,
currency: { type: String, default: 'USD', uppercase: true, index: true }
})
I want to remove the first two fields in the trade schema so that I can just have some kind of reference to the stock here. How can I do this?
use the populate like this:
MyModel.populate([{ path: 'author', select: 'username name -_id' }]);
the -fieldName or in your case -_id will deduct it from the projection.
For future reference, I solved this using populate virtuals as follows:
stockSchema.virtual('trades', {
ref: 'Trade',
localField: 'symbolCode',
foreignField: 'symbolCode',
justOne: true
})
I have three schemas, that need them to be separated and I can't use subdocuments. The important one is this
export var TestSchema = new mongoose.Schema({
hash: { type: String, index: { unique: true }, default: common.randomHash },
date: { type: Date, default: Date.now },
result: { type: Object },
user: { type: mongoose.Schema.Types.ObjectId, ref: 'User' },
data: { type: Object },
finished: Date,
lang: { type: String, default: 'pt' },
benchmark: { type: String, required: true },
order: { type: mongoose.Schema.Types.ObjectId, ref: 'Transaction' },
/* TODO: remove */
name: { type: String }
});
I have a query that does the populate (it's actually a pagination helper, but I'm cutting to the chase):
TestModel.find({hide: {$ne: true}, user: id}).populate({
path: 'user',
match: {$or: [
{email: new RegExp(search, i)},
{name: new RegExp(search, i)},
{empresa: new RegExp(search, i)},
]}
}).exec().then(/*...*/)
when populate.match doesn't find anything, it sets the user to null. I tried setting the find({'user':{$ne: null}}) but it ignores it. (I guess the populate happen after the find call, maybe that's the reason).
Is there any way I can filter it in the database layer instead having to rely on iterating of the results, check for null then filter out?
This answer on GitHub clarifies that it is not possible with populate, due to how MongoDB works. However, you should be able to do it with $lookup.