Merging two Mongoose query results, without turning them into JSON - mongodb

I have two Mongoose model schemas setup so that the child documents reference the parent documents, as opposed to the Parent documents having an array of Children documents. (Its like this due to the 16MB size limit restriction on documents, I didnt want to limit the amount of relationships between Parent/Child docs):
// Parent Model Schema
const parentSchema = new Schema({
name: Schema.Types.String
})
// Child Model Schema
const childSchema = new Schema({
name: Schema.Types.String,
_partition: {
type: Schema.Types.ObjectId,
ref: 'Parent'
}
})
I want to create a static method that I can query for a Parent document, then query for any Child documents that match the parent document, then create a new item in the parent document that will reference the Children array.
Basically if the Parent document is:
{
_id: ObjectId('56ba258a98f0767514d0ee0b'),
name: 'Foo'
}
And the child documents are:
[
{
_id: ObjectId('56b9b6a86ea3a0d012bdd062'),
name: 'Name A',
_partition: ObjectId('56ba258a98f0767514d0ee0b')
},{
_id: ObjectId('56ba7e9820accb40239baedf'),
name: 'Name B',
_partition: ObjectId('56ba258a98f0767514d0ee0b')
}
]
Then id be looking to have something like:
{
_id: ObjectId('56ba258a98f0767514d0ee0b'),
name: 'Foo',
children: [
{
_id: ObjectId('56b9b6a86ea3a0d012bdd062'),
name: 'Name A',
_partition: ObjectId('56ba258a98f0767514d0ee0b')
},{
_id: ObjectId('56ba7e9820accb40239baedf'),
name: 'Name B',
_partition: ObjectId('56ba258a98f0767514d0ee0b')
}
]
}
Also, I want them to remain Mongoose documents, so I can update the Parents and Assets if I need to.
I was able to accomplish this by using toJSON on the Parent, then creating a new item that would hold the Child docs, but then obviously the Parent document isn't a real document..
The error I kept getting when I tried this was that I couldnt create a new element in the Document that wasnt in the schema.
I know I could do something like create a Virtual item that would return the promise that would query the Children, but im looking to have one static method, that returns one response (meaning they dont have to handle the virtual item as a promise or callback)
Let me know if this is possible. Thanks!

FYI, this apparently isn't possible, I've tried a few things and it doesn't seem like it will work.

Use the .populate() method of the schema.
Parent.find(query)
.populate("children")
.exec((err, items) => {
if (err) {
...
}
...
});

Related

Mongoose product category design?

I would like to create an eCommerce type of database where I have products and categories for the products using Mongodb and Mongoose. I am thinking of having two collections, one for products and one for categories. After digging online, I think the category should be as such:
var categorySchema = {
_id: { type: String },
parent: {
type: String,
ref: 'Category'
},
ancestors: [{
type: String,
ref: 'Category'
}]
};
I would like to be able to find all the products by category. For example "find all phones." However, the categories may be renamed, updated, etc. What is the best way to implement the product collection? In SQL, a product would contain a foreign key to a category.
A code sample of inserting and finding a document would be much appreciated!
Why not keep it simple and do something like the following?
var product_Schema = {
phones:[{
price:Number,
Name:String,
}],
TV:[{
price:Number,
Name:String
}]
};
Then using projections you could easily return the products for a given key. For example:
db.collection.find({},{TV:1,_id:0},function(err,data){
if (!err) {console.log(data)}
})
Of course the correct schema design will be dependent on how you plan on querying/inserting/updating data, but with mongo keeping things simple usually pays off.

Updating an array field in a mongodb collection

I am trying to update my collection which has an array field(initially blank) and for this I am trying this code
Industry.update({_id:industryId},
{$push:{categories: id:categoryId,
label:newCategory,
value:newCategory }}}});
No error is shown, but in my collection just empty documents({}) are created.
Note: I have both categoryId and newCategory, so no issues with that.
Thanks in advance.
This is the schema:
Industry = new Meteor.Collection("industry");
Industry.attachSchema(new SimpleSchema({
label:{
type:String
},
value:{
type:String
},
categories:{
type: [Object]
}
}));
I am not sure but maybe the error is occuring because you are not validating 'categories' in your schema. Try adding a 'blackbox:true' to your 'categories' so that it accepts any types of objects.
Industry.attachSchema(new SimpleSchema({
label: {
type: String
},
value: {
type: String
},
categories: {
type: [Object],
blackbox:true // allows all objects
}
}));
Once you've done that try adding values to it like this
var newObject = {
id: categoryId,
label: newCategory,
value: newCategory
}
Industry.update({
_id: industryId
}, {
$push: {
categories: newObject //newObject can be anything
}
});
This would allow you to add any kind of object into the categories field.
But you mentioned in a comment that categories is also another collection.
If you already have a SimpleSchema for categories then you could validate the categories field to only accept objects that match with the SimpleSchema for categories like this
Industry.attachSchema(new SimpleSchema({
label: {
type: String
},
value: {
type: String
},
categories: {
type: [categoriesSchema] // replace categoriesSchema by name of SimpleSchema for categories
}
}));
In this case only objects that match categoriesSchema will be allowed into categories field. Any other type would be filtered out. Also you wouldnt get any error on console for trying to insert other types.(which is what i think is happening when you try to insert now as no validation is specified)
EDIT : EXPLANATION OF ANSWER
In a SimpleSchema when you define an array of objects you have to validate it,ie, you have to tell it what objects it can accept and what it can't.
For example when you define it like
...
categories: {
type: [categoriesSchema] // Correct
}
it means that objects that are similar in structure to those in another SimpleSchema named categoriesSchema only can be inserted into it. According to your example any object you try to insert should be of this format
{
id: categoryId,
label: newCategory,
value: newCategory
}
Any object that isn't of this format will be rejected while insert. Thats why all objects you tried to insert where rejected when you tried initially with your schema structured like this
...
categories: {
type: [Object] // Not correct as there is no SimpleSchema named 'Object' to match with
}
Blackbox:true
Now, lets say you don't what your object to be filtered and want all objects to be inserted without validation.
Thats where setting "blackbox:true" comes in. If you define a field like this
...
categories: {
type: [Object], // Correct
blackbox:true
}
it means that categories can be any object and need not be validated with respect to some other SimpleSchema. So whatever you try to insert gets accepted.
If you run this query in mongo shell, it will produce a log like matched:1, updated:0. Please check what you will get . if matched is 0, it means that your input query is not having any matching documents.

Meteorjs - What is the proper way to join collections on backend

I am very new to meteor.js and try to build an application with it. This time I wanted to try it over MEAN stack but at this point I am struggled to understand how to join two collection on server side...
I want very identical behaviour like mongodb populate to fetch some properties of inner document.
Let me tell you about my collection it is something like this
{
name: 'Name',
lastName: 'LastName',
anotherObject: '_id of another object'
}
and another object has some fields
{
neededField1: 'asd',
neededField2: 'zxc',
notNeededField: 'qwe'
}
So whenever I made a REST call to retrieve the first object I want it contains only neededFields of inner object so I need join them at backend but I cannot find a proper way to do it.
So far while searching it I saw some packages here is the list
Meteor Collections Helper
Publish with Relations
Reactive joins in Meteor (article)
Joins in Meteor.js (article)
Meteor Publish Composite
You will find the reywood:publish-composite useful for "joining" related collections even though SQL-like joins are not really practical in Mongo and Meteor. What you'll end up with is the appropriate documents and fields from each collection.
Using myCollection and otherCollection as pseudonyms for your two collections:
Meteor.publishComposite('pseudoJoin', {
find: function() {
return myCollection.find();
},
children: [
{
find: function(doc) {
return otherCollection.find(
{ _id: post.anotherObject },
{ fields: { neededField1: 1, neededField2: 1 } });
}
}
]
});
Note that the _id field of the otherCollection will be included automatically even though it isn't in the list of fields.
Update based on comments
Since you're only looking to return data to a REST call you don't have to worry about cursors or reactivity.
var myArray = myCollection.find().fetch();
var myOtherObject = {};
var joinedArray = myArray.map(function(el){
myOtherObject = otherCollection.findOne({ _id: el.anotherObject });
return {
_id: el._id,
name: el.name,
lastName: el.lastName,
neededField1: myOtherObject.neededField1,
neededField2: myOtherObject.neededField2
}
});
console.log(joinedArray); // These should be the droids you're looking for
This is based on a 1:1 relation. If there are many related objects then you have to repeat the parent object to the number of children.

MongoDB: Get all mentioned items

I've got two relations in my Mongoose/MongoDB-Application:
USER:
{
name: String,
items: [{ type: mongoose.Schema.ObjectId, ref: 'Spot' }]
}
and
ITEM
{
title: String,
price: Number
}
As you can see, my user-collection containing a "has-many"-relation to the item-collection.
I'm wondering how to get all Items which are mentioned in the items-field of on specific user.
Guess its very common question, but I haven't found any solution on my own in the Docs or elsewhere. Can anybody help me with that?
If you are Storing items reference in user collection,then fetch all items from user,it will give you a array of object ids of items and then you can access all items bases on their ids
var itemIdsArray = User.items;
Item.find({
'_id': { $in: itemIdsArray}
}, function(err, docs){
console.log(docs);
});
You can get the items at the same time you query for the user, by using Mongoose's support for population:
User.findOne({_id: userId}).populate('items').exec(function(err, user) {
// user.items contains the referenced docs instead of just the ObjectIds
});

How do I use new Meteor.Collection.ObjectID() in my mongo queries with meteor?

I have a Collection that has documents with an array of nested objects.
Here is fixture code to populate the database:
if (Parents.find().count() == 0) {
var parentId = Parents.insert({
name: "Parent One"
});
Children.insert({
parent: parentId,
fields: [
{
_id: new Meteor.Collection.ObjectID(),
position: 3,
name: "three"
},
{
_id: new Meteor.Collection.ObjectID(),
position: 1,
name: "one"
},
{
_id: new Meteor.Collection.ObjectID(),
position: 2,
name: "two"
},
]
});
}
You might be asking yourself, why do I even need an ObjectID when I can just update based off of the names. This is a simplified example to a much more complex schema that I'm currently working on and the the nested object are going to be created dynamically, the ObjectID's are definitely going to be necessary to make this work.
Basically, I need a way to save those nested objects with a unique ID and be able to update the fields by their _id.
Here is my Method, and the call I'm making from the browser console:
Meteor.methods({
upChild: function( options ) {
console.log(new Meteor.Collection.ObjectID());
Children.update({_id: options._id, "fields._id": options.fieldId }, {$set: {"fields.$.position": options.position}}, function(error){
if(error) {
console.log(error);
} else {
console.log("success");
}
});
}
});
My call from the console:
Meteor.call('upChild', {
_id: "5NuiSNQdNcZwau92M",
fieldId: "9b93aa1ef3868d762b84d2f2",
position: 1
});
And here is a screenshot of the html where I'm rendering all of the data for the Parents and Children collections:
Just an observation, as I was looking how generate unique IDs client side for a similar reason. I found calling new Meteor.Collection.ObjectID() was returning a object in the form 'ObjectID("abc...")'. By assigning Meteor.Collection.ObjectID()._str to _id, I got string as 'abc...' instead, which is what I wanted.
I hope this helps, and I'd be curious to know if anyone has a better way of handling this?
Jason
Avoid using the _str because it can change in the future. Use this:
new Meteor.Collection.ObjectID().toHexString() or
new Meteor.Collection.ObjectID().valueOf()
You can also use the official random package:
Random.id()