I have a sub document called services in a collection it contains serviceID and type. serviceID is referred to two collections internalservice and externalservice varies based on the type field.
internalServices:[{
serviceID:ObjectId('0000000000000'),
serviceDesc:'sweeping'
},
{
serviceID:ObjectId('0000000000000'),
serviceDesc:'floor cleaning'
}]
externalServices:[{
serviceID:ObjectId('0000000000000'),
serviceDesc:'painting'
},
{
serviceID:ObjectId('0000000000000'),
serviceDesc:'white washing'
}]
Above two are lookup collection. And here the company collection
_id:"xxxxxxxxxxxxxxxx",
name: 'xxxx',
Address:'xxx',
services:[{
serviceID:ObjectId('0000000000000'),
type: internalservice
},
{
serviceID:ObjectId('0000000000000'),
type: externalservice
}]
Here, i want to populate service description based on type.
Is it possible to have conditional path at populate?
Here's my code
Company.findOne({"_id": mongoose.Types.ObjectId(req.params.companyID)},
{})
.populate('services.serviceID','serviceDesc','InternalService')
.exec(function (err, companyInfo) {
console.log(companyInfo);
});
This populates internal service description but i need to populate external service description for type externalservice. When i have two populate the second populate replaces the result with null for unmatched documents.
You can include in populate where conditions like:
Story
.find(...)
.populate({
path: 'fans',
match: { age: { $gte: 21 }},
select: 'name -_id',
options: { limit: 5 }
})
.exec()
Here is the Mongoose Populate Documentation
Related
I have two collections Categories and Subcategories inside a Categories collection. I have an array that is storing the ids of subcategories that are stored in Subcategories collection. Below is my document structure:
Categories collection
{
id:65,
title:"Automotive",
active:true,
subcategories:[35,28,30]
}
subcategories collection
{
id:35,
title:"Automotive technology",
category_id:65,
active:true
},
{
id:28,
title:"Automotive coatings",
category_id:65,
active:true
},
{
id:30,
title:"Machinery and equipments",
category_id:65,
active:true
}
As seen in above collection 3 documents from subcategories collection have been associated with the category document. I want to fetch data in below format on single API hit.
API response should be in below format:
{
data:{
category:{
id:65,
title:"Automotive",
subcategories:[{
id:35,
name:"Automotive technology",
},
{
id:28,
name:"Automotive coatings",
},
{
id:30,
name:"Machinery and equipments",
}]
},
category:{
id:66,
title:"Food",
subcategories:[{
id:23,
name:"Drinks",
},
{
id:2,
name:"Additives",
}]
},
},
messsage:"Success",
code:200
}
As of now I am able to get data in 2 api hits that is like first getting all the categories
const category = await db.categories.find({});
Then on click of some particular category fetching all the sub categories based on the category id.
const subCategories = await db.SubCategories.find({category_id:id});
How can I get the above data in desired format in single API hit?
You need something like this, also, if you use mongoose, you can use .populate()
To format data you can use $project stage in aggregation pipeline or projection in .find()
If you want to use Mongoose with populate:
CategorySchema:
const CategorySchema= new mongoose.Schema({
...
subCategories: [{ type: mongoose.Schema.Types.ObjectId, ref: 'SubCategory' }],
...
});
need _id column on reference table
ref content is must be equal to model name like
module.exports = mongoose.model('SubCategory', SubCategorySchema);
Controller:
const categories = await Category.find({})
.populate({
path: 'subCategories'
})
path content is must be equal to column name
If you want to write with Mongo query:
db.getCollection("categories").aggregate([
{
$lookup:
{
from: 'subCategories',
localField: 'subCategories',
foreignField: 'id',
as: 'subCategories'
}
}
])
You get empty object because you are not using "_id" field for join schemas. If you want to use "id" field u need to use virtuals on Mongoose:
https://mongoosejs.com/docs/tutorials/virtuals.html#populate
I have a document in mongoDB structured like that
_id: ObjectId("generatedByMongo"),
name: {
required: true,
type: String,
trim: true
},
last: {
required: true,
type: String,
trim: true
},
grades: [{
grade: {
_id: ObjectId(""),
grade: Number,
date: date
}
}]
And to server I send array of objects containing 3 fields
[
{studentId}, {gradeId}, {newGrade}
]
What I'm trying to accomplish is I want to find in within that user collection grade with given gradeId and update it's value to newGrade. As far as I tried to do that I have done this
router.patch('/students/updateGrade',async(req,res) => {
const studentId = req.body.updateGradeArray[0].studentId;
const gradeId = req.body.updateGradeArray[0].gradeId;
const newGrade = req.body.updateGradeArray[0].newGrade;
try {
const student = await Student.find({_id: studentId})
.select({'grades': {$elemMatch: {_id: gradeId}}});
} catch(e) {
console.log(e);
}
}
);
If you intend to update just grade.grade(the number value), try this:
Student.updateOne(
// Find a document with _id matching the studentId
{ "_id": studentId },
// Update the student grade
{ $set: { "grades.$[selectedGrade].grade": newGrade } },
{ arrayFilters: [{ "selectedGrade._id": gradeId }] },
)
Why this should work:
Since you are trying to update a student document, you should be using one of MongoDB update methods not find. In the query above, I'm using the updateOne method. Inside the updateOne, I am using a combination of $set and $[identifier] update operators to update the student grade.
I hope this helps✌🏾
Currently I have the following structure for one of my documents
Company: {
Buildings: [{
Users: [ { _id: ObjectID, name: String, number: String } ]
}]
}
I'm trying to update the user's name and number and currently have tested and verified the following query in mongo:
db.companies.update(
{ "_id": companyID, "buildings._id": buildingID, "buildings.users._id": userID }
,
{ $set: { "buildings.$.users.0.name": "A new name for the user" } }
);
This query updates correctly however when I run the same exact query using mongoose
Company.findOneAndUpdate(
{ _id: companyID, "buildings._id": buildingID, "buildings.users._id": userID }
,
{ $set: { "buildings.$.users.0.name": newName }})
I get no error but the update is not performed.
Is the updating of a deep nested array not available on Mongoose?
Answer was found in an alternative answer to this question:
Answer: https://stackoverflow.com/a/28952991/1327815
Say I have a collection of documents, each one managing a discussion between a teacher and a student:
{
_id,
teacherId,
studentId,
teacherLastMessage,
studentLastMessage
}
I will get queries with 3 parameters: an _id, a userId and a message.
I'm looking for a way to update the teacherLastMessage field or studentLastMessage field depending on which one the user is.
At the moment, I have this:
return Promise.all([
// if user is teacher, set teacherLastMessage
db.collection('discussions').findOneAndUpdate({
teacherId: userId,
_id
}, {
$set: {
teacherLastMessage: message
}
}, {
returnOriginal: false
}),
// if user is student, set studentLastMessage
db.collection('discussions').findOneAndUpdate({
studentId: userId,
_id
}, {
$set: {
studentLastMessage: message
}
}, {
returnOriginal: false
})
]).then((results) => {
results = results.filter((result) => result.value);
if (!results.length) {
throw new Error('No matching document');
}
return results[0].value;
});
Is there a way to tell mongo to make a conditional update, based on the field matched? Something like this:
db.collection('discussions').findOneAndUpdate({
$or: [{
teacherId: userId
}, {
studentId: userId
}],
_id
}, {
$set: {
// if field matched was studentId, set studentLastMessage
// if field matched was teacherId, set teacherLastMessage
}
});
Surely it must be possible with mongo 3.2?
What you want would require referencing other fields inside of $set. This is currently impossible. Refer to this ticket as an example.
First of all, your current approach with two update queries looks just fine to me. You can continue using that, just make sure that you have the right indexes in place. Namely, to get the best performance for these updates, you should have two compound indexes:
{ _id: 1, teacherId: 1 }
{ _id: 1, studentId: 1 }.
To look at this from another perspective, you should probably restructure your data. For example:
{
_id: '...',
users: [
{
userId: '...',
userType: 'student',
lastMessage: 'lorem ipsum'
},
{
userId: '...',
userType: 'teacher',
lastMessage: 'dolor sit amet'
}
]
}
This would allow you to perform your update with a single query.
Your data structure is a bit weird, unless you have a specific business case which requires the data the be molded that way i would suggest creating a usertype unless a user can both be a teacher and a student then keep your structure.
The $set{} param can take a object, my suggestion is to do your business logic prior. You should already know prior to your update if the update is going to be for a teacher or student - some sort of variable should be set / authentication level to distinguish teachers from students. Perhaps on a successful login in the callback you could set a cookie/local storage. Regardless - if you have the current type of user, then you could build your object earlier, so make an object literal with the properties you need based on the user type.
So
if(student)
{
var updateObj = { studentLastMsg: msg }
}
else
{
var updateObj = { teacherLastMsg: msg }
}
Then pass in your update for the $set{updateObj} I'll make this a snippet - on mobile
Schema of group and member are as below:
var group=new Schema({
group_id:Number,
group_name:String,
members:[member]
});
var member=new Schema({
member_id:number,
name:String,
});
Sample document after inserting some record in group collection
[{
_id:55ff7fca8d3f6607114dc57d
group_id:1001,
group_name:"tango mike",
members:[
{
_id:44ff7fca8d3f6607114dc21c
member_id:2001,
member_name:"Bob martin" ,
address:String,
sex:String
},
{
_id:22ff7fca8d3f6607114dc22d
member_id:2002,
member_name:"Marry",
address:String,
sex:String
},
{
_id:44ff7fca8d3f6607114dc23e
member_id:2003,
member_name:"Alice" ,
address:String,
sex:String
}
]
}]
My problem:
I am trying to update record of individual group member(element of subdocument members). While updating I have follwing data group: _id, group_id, members:_id and newdata. I am trying like this; but it is not working
var newData={
member_name:"Alice goda" ,
address:"xyz",
sex:"F"
}
groupModel.findOne({"_id":"55fdbaa7457aa1b9bd7f7cf7","group_id":1001},'members -_id',function(err,groupMembers){
if(err)
{
res.json({
"isError":true,
"error":{
"status":1042,
"message":err
}
});
}
else
{
var mem=groupMembers.id("44ff7fca8d3f6607114dc23e");
mem.member_name=newData.member_name;
mem.address=newData.address;
mem.sex=newData.sex;
mem.save(function(err,data){
if(!err)
//sucessfull updated
});
res.json(groupDetails);
}
});
As I understand from your question details, you would like to update one object from the members array, in accordance with the criteria that you specify.
Thus, in order to accurately run the update query for your use case, you could run the following update operation against your collection:
db.collection.update({ _id: "55ff7fca8d3f6607114dc57d",
group_id:1001,
members: {
$elemMatch: { _id: "44ff7fca8d3f6607114dc23e" }
}
},
{ $set: {
"members.$.member_name": "Alice goda",
"members.$.address": "xyz",
"members.$.sex": "F"
}});
Still, be aware that the $ positional operator only updates the first array item that matches your query.
Unfortunately, there is no possibility of updating all the array elements that match your criteria in a single operation. As you can see on MongoDB Jira, the aforementioned feature is one of the most requested functionality, but it has not yet been directly implemented in MongoDB.