I am creating an application that allows the user to create subtables from master tables, where he/she can specify a range of rows to be included in the subtable.
This is my Subtable model:
// Imports
const mongoose = require('mongoose');
const timestamps = require('mongoose-timestamp');
// Setup
const Schema = mongoose.Schema;
const ViewSchema = new Schema({
name: {
type: String,
required: true
},
table: {
type: mongoose.Types.ObjectId,
required: true,
ref: 'Table'
},
range: [
[
{
start: { type: mongoose.Types.ObjectId, ref: 'Row' },
end: { type: mongoose.Types.ObjectId, ref: 'Row' }
}
]
],
columns: {
type: Object,
required: true
}
});
ViewSchema.plugin(timestamps);
module.exports = mongoose.model('View', ViewSchema);
I currently store the starting row of the range and the ending row.
Now I wanted to know that if there is a way I can select only the documents that are inserted after the starting row and before the ending row so I don't have to pull 1000's of rows and filter them on the client side.
And if this is not possible, then I would love to know about any other solution.
Thanks a bunch!
A very naive solution to do this is using $gt and $lt operators, like this:
RowModel.find({ _id: { $gt: ObjectIdOfTheStart, $lt: ObjectIdOfTheEnd } });
So this will return all the rows which have an ObjectId greater than that of the start row and lower than that of the end row.
More on $gt and $lt.
Also as #the_mahasagar mentioned that you must use something like start and end dates, querying ObjectId does the same as well, as mentioned by Steve Ridout here.
Word of caution, I wouldn't recommend doing something like this. you should use some other kind of identifier for querying these rows.
Related
I have two Entities, Organization and Applications. One organization can have many Applications.
const organization = mongoose.Schema(
{
name: {
type: String,
required: [true, 'Organization name is required.']
}, // min 1 max 255
// administrators get it from user table with org and role.
applications: [
// use populate in query
{
type: mongoose.Types.ObjectId,
ref: 'Application'
}
]
I am trying to query Organization with two applications and its returning a blank array
const organizations = await Organization.find({
'applications': {
$all: [
'636bdf70bcd2d24005061023',
'6373ba91f53f95ca187809d6'
]
}
}).populate('applications');
I tried running the same expression in MongoDB compass and it works. What am I doing wrong here ?
Based on your schema model, the applications field is an array of ObjectIDs, not an array of objects where each object would have _id property.
So instead of applications._id, it should be applications:
const organizations = await Organization.find({
applications: {
$all: ['636bdf70bcd2d24005061023', '6373ba91f53f95ca187809d6']
}
})
.populate('applications');
I have a User collection and a Task Collection. Many Users can have many Tasks, and Many Tasks can have many Users. The proper way I believe in doing this is the following models:
var UserSchema = new Schema({
id: ObjectId,
username: { type: String, required: true },
assignments: [ {type : mongoose.Schema.ObjectId, ref : 'Assignment'} ]
});
var TaskSchema = new Schema({
id: ObjectId,
title: { type: String, default: '' },
information: { type: String, default: '' },
assignments: [ {type : mongoose.Schema.ObjectId, ref : 'Assignment'} ]
});
var AssignmentSchema = new Schema({
id: ObjectId,
isCompleted: { type: Boolean, default: false },
completionDate: { type: Date, default: null },
tasks: [ {type : mongoose.Schema.ObjectId, ref : 'Task'} ],
users: [ {type : mongoose.Schema.ObjectId, ref : 'User'} ]
});
If the above models are correct, how do you insert a Task with multiple user assignments? I understand that you would create the Task document first to get its ObjectId, but after that would you just insert all of the assignments into the Assignment collection (with their proper Task and User objectId's) and thats it? Or would I have to insert all of the assignments then edit each individual User and Task to insert the AssignmentId into their assignments property.
I am sure there is a stack over flow question like this already, but I have not been able to find one. Any help is appreciated!
I believe you have the answer in your question.
Create a new task, capture the task id. Then find or create a new user, edit or add the task’s id, capture the user id. Add the user id to the task. Repeat for additional users.
I believe this is what you say in the final part of your question?
I don’t see why this cannot work.
I have the following Schema with a array of ObjectIds:
const userSchema = new Schema({
...
article: [{
type: mongoose.Schema.Types.ObjectId,
}],
...
},
I will count the array elements in the example above the result should be 10.
I have tried the following but this doesn't worked for me. The req.query.id is the _id from the user and will filter the specific user with the matching article array.
const userData = User.aggregate(
[
{
$match: {_id: id}
},
{
$project: {article: {$size: '$article'}}
},
]
)
console.log(res.json(userData));
The console.log(article.length) give me currently 0. How can I do this? Is the aggregate function the right choice or is a other way better to count elements of a array?
Not sure why to use aggregate when array of ids is already with user object.
Define articles field as reference:
const {Schema} = mongoose.Schema;
const {Types} = Schema;
const userSchema = new Schema({
...
article: {
type: [Types.ObjectId],
ref: 'Article',
index: true,
},
...
});
// add virtual if You want
userSchema.virtual('articleCount').get(function () {
return this.article.length;
});
and get them using populate:
const user = await User.findById(req.query.id).populate('articles');
console.log(user.article.length);
or simply have array of ids:
const user = await User.findById(req.query.id);
console.log(user.article.length);
make use of virtual field:
const user = await User.findById(req.query.id);
console.log(user.articleCount);
P.S. I use aggregate when I need to do complex post filter logic which in fact is aggregation. Think about it like You have resultset, but You want process resultset on db side to have more specific information which would be ineffective if You would do queries to db inside loop. Like if I need to get users which added specific article by specific day and partition them by hour.
I have models called "Activities" that I am querying for (using Mongoose). Their schema looks like this:
var activitySchema = new mongoose.Schema({
actor: {
type: mongoose.Schema.ObjectId,
ref: 'User',
required: true
},
recipient: {
type: mongoose.Schema.ObjectId,
ref: 'User'
},
timestamp: {
type: Date,
default: Date.now
},
activity: {
type: String,
required: true
},
event: {
type: mongoose.Schema.ObjectId,
ref: 'Event'
},
comment: {
type: mongoose.Schema.ObjectId,
ref: 'Comment'
}
});
When I query for them, I am populating the actor, recipient, event, and comment fields (all the references). After that, I also deep-populate the event field to get event.creator. Here is my code for the query:
var activityPopulateObj = [
{ path: 'event' },
{ path: 'event.creator' },
{ path: 'comment' },
{ path: 'actor' },
{ path: 'recipient' },
{ path: 'event.creator' }
],
eventPopulateObj = {
path: 'event.creator',
model: User
};
Activity.find({ $or: [{recipient: user._id}, {actor: {$in: user.subscriptions}}, {event: {$in: user.attending}}], actor: { $ne: user._id} })
.sort({ _id: -1 })
.populate(activityPopulateObj)
.exec(function(err, retrievedActivities) {
if(err || !retrievedActivities) {
deferred.reject(new Error("No events found."));
}
else {
User.populate(retrievedActivities, eventPopulateObj, function(err, data){
if(err) {
deferred.reject(err.message);
}
else {
deferred.resolve(retrievedActivities);
}
});
}
});
This is already a relatively complex query, but I need to do even more. If it hits the part of the $or statement that says {actor: {$in: user.subscriptions}}, I also need to make sure that the event's privacy field is equal to the string public. I tried using $elemMatch, but since the event has to be populated first, I couldn't query any of its fields. I need to achieve this same goal in multiple other queries, as well.
Is there any way for me to achieve this further filtering like I have described?
The answer is to change your schema.
You've fallen into the trap that many devs have before you when coming into document database development from a history of using relational databases: MongoDB is not a relational database and should not be treated like one.
You need to stop thinking about foreign keys and perfectly normalized data and instead, keep each document as self-contained as possible, thinking about how to best embed relevant associated data within your documents.
This doesn't mean you can't maintain associations as well. It might mean a structure like this, where you embed only necessary details, and query for the full record when needed:
var activitySchema = new mongoose.Schema({
event: {
_id: { type: ObjectId, ref: "Event" },
name: String,
private: String
},
// ... other fields
});
Rethinking your embed strategy will greatly simplify your queries and keep the query count to a minimum. populate will blow your count up quickly, and as your dataset grows this will very likely become a problem.
You can try below aggregation. Look at this answer: https://stackoverflow.com/a/49329687/12729769
And then, you can use fields from $addFields in your query. Like
{score: {$gte: 5}}
but since the event has to be populated first, I couldn't query any of its fields.
No can do. Mongodb cannot do joins. When you make a query, you can work with exactly one collection at a time. And FYI all those mongoose populates are additional, distinct database queries to load those records.
I don't have time to dive into the details of your schema and application, but most likely you will need to denormalize your data and store a copy of whatever event fields you need to join on in the primary collection.
I have an existing News articles section that I want to add categories to for more refined searching, my Schema's are as follows:
var ArticleSchema = new Schema({
title: String,
body: String,
author: {
type: Schema.Type.ObjectId,
ref: 'User',
required: true
},
image: String,
catagories: [{
type: Schema.Types.ObjectId, ref: 'Catagory'
}],
meta: {
created: {
type: Date,
'default': Date.now,
set: function(val) {
return undefined;
}
},
updated: {
type: Date,
'default': Date.now
}
}
});
ArticleSchema.statics.search = function (str, callback) {
var regexp = new RegExp(str, 'i');
return this.find({'$or': [{title: regexp}, {body: regexp}]}, callback);
};
module.exports = ArticleSchema;
var CatagorySchema = new mongoose.Schema({
name: { type: String, unique: true },
});
module.exports = CatagorySchema;
I want a user friendly input for selecting categories (don't even know what is best here, be it check-box's or a simple comma separated text input etc.). My question is what is the best practice for obtaining this kind of input and translating that into the Article Schema (providing the categories exist). If anyone could point me in the right direction it would be much appreciated. Thanks.
Keep the category names you want to search for in an array
{
categories: ["cat1", "cat2"]
}
then you can add an index to it and do a $in query. the current schema is not very good because you cannot look for the category in a single query but need to resolve all the "categories" links first.