I'm currently working on a project where I have 3 models with a child and parent structure.
City has multiple Locations which has multiple Stones. Each Stone only has one Location as parent and each Location only has one City as parent.
Now, I want to create a list of all Stones that 'belong' (through a Location) to a specific City. How would I retrieve all these associations, without having to do the following:
City.find({
where: {
id: 1337
},
include: [{
model: Location,
include: [{
model: Stone
}]
}]
})
.then((city) => {
city.stones = [].concat.apply([], city.locations.map(location => location.stones));
});
I'm trying to find out if there's a "SQL only" solution, so not retrieving data / having to execute JavaScript to generate this array.
Related
Here's my case.
I'm building a system in which you have users (consider them admins) that create employees and a performance report is created for every employee. The users can only view employees that were created by users from the same company. However, another company can create a report for an employee from a different company using a search field. Once a report is created for that employee, then they can view that employee within the employees list, if the report is not there, they wouldn't have seen it within that list.
Note: The model names are changed but have same characteristics
I'm trying to have an endpoint which returns all employees based on either of these two scenarios:
Return all employees created by the user which their company belong to the same company as the user initiating the request.
Return all employees that (if they don't belong to the same company as the user who created the employee) have a report associated to them and the report was created by a user from the same company as the user initiating the request.
Here's a brief ERD that explains the relationship between the models:
Here's the code which uses nested joins:
async function getAll(company) {
return await Employee.findAll({
where: {
[Op.or]: [
{
'$User.company$': { [Op.eq]: company }
},
{
'$Report.User.company$': { [Op.eq]: company }
}
]
},
include: [
{
attributes: [],
model: User.scope('withoutPassword'),
},
{
attributes: [],
model: Report,
include: {
attributes: [],
model: User.scope('withoutPassword'),
}
}
]
})
.then(employees => {
return employees
});
}
I have a model Booking, which is having hasMany relation with hotels, and hotel is having one to one relation with supppliers.
What i need is, get all booking where supplier_id = 33333.
I am trying this
BOOKINGS.findAll({
where: {
'hotels.supplier.supplier_id' : '32',
},
include: [
{
model: HOTELS,
include: [
{
model: SUPPLIERS,
],
}
],
limit : 30,
offset: 0
})
It throws error like hotels.supplier... column not found.. I tried all things because on docs of sequelze it only gives solution to add check which adds where inside the include which i can't use as it adds sub queries.
I don't want to add where check alongwith supplier model inside the include array, because it adds sub queries, so If i am having 1000 bookings then for all bookings it will add sub query which crashes my apis.
I need a solutions like this query in Sequelize.
Select col1,col2,col3 from BOOKINGS let join HOTELS on BOOKINGS.booking_id = HOTELS.booking_id, inner join SUPPLIERS on BOOKINGS.supplier_id = SUPPLIERS.supplier_id
Adding a where in the include object will not add a sub query. It will just add a where clause to the JOIN which is being applied to the supplier model. It will not crash your API in anyway. You can test it out on your local machine plenty of times to make sure.
BOOKINGS.findAll({
include: [
{
model: HOTELS,
include: [
{
model: SUPPLIERS,
where: { supplier_id: 32 }
}
]
}
],
limit: 30,
offset: 0
})
If you still want to use the query on the top level you can use sequelize.where+ sequelize.literal but you will need to use the table aliases that sequelize assigns. e.g this alias for supplier table will not work hotels.supplier.supplier_id. Sequelize assings table aliases like in the example I have shown below:
BOOKINGS.findAll({
where: sequelize.where(sequelize.literal("`hotels->suppliers`.supplier_id = 32")),
include: [
{
model: HOTELS,
include: [SUPPLIERS]
}
],
limit: 30,
offset: 0
})
When I associate two models, how do I prevent name collisions?
// Find all projects with a least one task where task.state === project.state
Project.findAll({
include: [{
model: Task,
where: { state: Sequelize.col('project.state') }
}]
})
In this example, what if there was a name property in both project and task.
I'm building a Node/Express/Postgres version of an app that I already built in Rails. I'm learning Node, so I figured I'd rebuild something that I know works.
For now, I'm dumping everything in one file (set up my database, defined my models, etc.), just to make sure I have everything set up correctly before I divvy them up into different files.
I set up my postgres database at the very top of the file, like so:
var Sequelize = require('sequelize');
var db = new Sequelize('my_database_name', 'my_username', null, {
host: 'localhost',
dialect: 'postgres',
});
With regard to my models, I have a Politician model:
var Politician = db.define("politician", {
name: {
type: Sequelize.STRING,
},
politicalParty: {
type: Sequelize.STRING
}
});
A Category model:
var Category = db.define("category", {
name: {
type: Sequelize.STRING
},
keywords: {
type: Sequelize.ARRAY(Sequelize.TEXT)
},
});
And a join model of Politician and Category, called "Interest". Because Interest is a join model, it will have a "politicianId" and "categoryId" properties....but will those properties automatically generate in the database? And so, is this how I would define the Interest model, with no properties?
Interest Model:
var Interest = db.define("interest")
Or, will I have to be specific, and create "politicianId" and "categoryId" properties? Like so:
Interest Model:
var Interest = db.define("interest", {
id: {
type: Sequelize.INTEGER,
primaryKey: true,
autoIncrement: true
},
categoryId: {
type: Sequelize.INTEGER,
foreignKey: true
},
politicianId: {
type: Sequelize.INTEGER,
foreignKey: true
}
});
Also, do I need the "foreignKey: true" bit? Or will it automatically know that those properties are foreign keys? Also, do I need the "id" property? I know models automatically create their own primary key "id"...but again, I've been at this for hours, looking at docs, and trying everything.
I then defined my associations (again, all of this is the same file):
Politician.belongsToMany(Category, {through: "Interest"});
Category.belongsToMany(Politician, {through: "Interest"});
The Node/Sequelize docs seems to suggest that defining those 2 associations above will automatically "create a new model called Interest with the equivalent foreign keys politicianId and categoryId." So, do I even need to define a "Interest" model? Also, do I need the follow associations to describe that Interest belongs to Politician and Category?
Interest.belongsTo(Politician);
Interest.belongsTo(Category);
If I don't write the associations saying that Interest belongs to Politican and Catetory, I don't get the "politicianId" and "categoryId" columns in the Interest table. Just the "id" and createdAt/updatedAt columns.
I then created an instance of Politician, Category, and Interest, to persist everything to the database, to see if everything is there and set up correctly:
Politician Object:
var politician1 = Politician.sync({force: true}).then(function(){
return Politician.create(aPoliticianObjectDefinedInthisFile);
});
This works perfectly. I see this object in the politician table in the database.
Category Object:
var category1 = Category.sync({force: true}).then(function(){
return Category.create(aCategoryObjectDefinedInThisFile);
});
This works perfectly. I see this object in the category table in the database.
Here is what doesn't work. Creating an instance/object of Interest and synching it to the database. My thinking is, if I put integers as values, it will know that "politicianId: 1" means point to the politician object with an id of 1, and the same for "categoryId: 1". But when I write it as I have it below, the Interest table doesn't even show up in the Postgres database at all.
Interest Object:
Interest.sync({force: true}).then(function(){
return Interest.create(
{
politicianId: 1,
categoryId: 1
}
);
});
However, when I create the object of Interest like this, with no properties defined, the Interest table appears in the database, along with the "politicianId" and "categoryId" columns, however, those columns are empty. The object's primary id is in there at 1, and the "createdAt" and "updatedAt" columns have data too. But the foreign key columns are blank.
Interest Object:
Interest.sync({force: true}).then(function()
{
return Interest.create(
{
// No properties defined.
}
);
}
);
Sorry for this long post, lol, but, in all:
Am I creating the "Interest" model correctly?
Am I writing the associations for "Interest" correctly?
Do I even need to write associations for Interest, if I already have associations for its parent classes, Politican and Category defined?
In my Rails app, my associations for Politican and Category are like so:
Politician has_many interests
Politican has_many categories through interests
Category has_many interests
Category has_many politicians through interests
Interest belongs_to politician
Interest belongs_to category
But I use the "belongsToMay" association in Node because I got an error telling me to do so.
Basically, I need to create an instance of Politician, an instance of Category, and an instance of Interest that has "politicianId" and "categoryId" columns that point to those aforementioned instances of those classes.
politicanABC -- id: 1
categoryABC -- id: 1
instanceABC -- id: 1; politicanId: 1 (referring to politicanABC); categoryid: 1 (referring to categoryABC).
My app is set up like that in Rails and works wonderfully.
Help and thank you in advance :-)
You don't have to define the Interest model if you are not going to add any additional fields. Sequelize will internally define the model and add all required fields once you do following:
Politician.belongsToMany(Category, {through: "Interest"});
Category.belongsToMany(Politician, {through: "Interest"});
Sync needs to run on database level and not on tables since Interest model is implicit at this point.
db.sync({force: true});
Sequelize will add relationship build methods on both Politician and Category instances. Category will have methods addPolitician(), addPoliticians([]), setPoliticians([]), getPliticians(). Politician instances will have similar functions to associate categories to them. You can connect these after create option is performed on both objects successfully.
Politician.create({name: 'John Doe', politicalParty: 'Nice Party'})
.then(function(politician) {
Category.create({name: 'Nicers'})
.then(function(category) {
politician.addCategory(category);
});
});
You can also search and associate existing items using helper methods. Alternatively you can associate objects manually by accessing db.models.Interest model and running creates on it.
I'm managing a MongoDB database for a building products store. The most immediate collection is products, right?
There are quite several products, however they all belong to one among a set of 5-8 categories and then to one subcatefory among a small set of subcategories.
For example:
-Electrical
*Wires
p1
p2
..
*Tools
p5
pn
..
*Sockets
p11
p23
..
-Plumber
*Pipes
..
*Tools
..
PVC
..
I will use Angular at web site client side to show whole products catalog, I think about AJAX for querying the right subset of products I want.
Then, I wonder whether I should manage one only collection like:
{
MainCategory1: {
SubCategory1: {
{},{},{},{},{},{},{}
}
SubCategory2: {
{},{},{},{},{},{},{}
}
SubCategoryn: {
{},{},{},{},{},{},{}
}
},
MainCategory2: {
SubCategory1: {
{},{},{},{},{},{},{}
}
SubCategory2: {
{},{},{},{},{},{},{}
}
SubCategoryn: {
{},{},{},{},{},{},{}
}
},
MainCategoryn: {
SubCategory1: {
{},{},{},{},{},{},{}
}
SubCategory2: {
{},{},{},{},{},{},{}
}
SubCategoryn: {
{},{},{},{},{},{},{}
}
}
}
Or a single collection per each category. The number of documents might not be higher than 500. However I care about a balance for:
quick DB answer,
easy server side DB querying, and
client-side Angular code for rendering results to html.
I'm using mongodb node.js module, not Mongoose now.
What CRUD operations will I do?
Inserts of products, I'd also like to have a way to obtain autogenerated ids (maybe sequential) per each new register. However, as it might seem natural I wouldn't offer the _id to the user.
Querying the whole documents set of a subcategory. Maybe just obtaining a few attributes at first.
Querying whole or a specific subset of attributes of a document (product) in particular.
Modifying a product's attributes values.
I agree client side should get the easiest result to render. However, to nest categories into products is still a bad idea. The trade off is once you want to change, for example, the name of a category, it will be a disaster. And if you think about the possible usecases, for example:
list all categories
find all subcategories of a certain category
find all products in a certain category
You'll find it hard to do these stuff with your data structure.
I had same situation in my current project. So here's what I do for your reference.
First, categories should be in a separate collection. DON'T nest categories into each other, as it will complicate the procedure to find all subcategories. The traditional way for finding all subcategories is to maintain an idPath property. For example, your categories are divided into 3 levels:
{
_id: 100,
name: "level1 category"
parentId: 0, // means it's the top category
idPath: "0-100"
}
{
_id: 101,
name: "level2 category"
parentId: 100,
idPath: "0-100-101"
}
{
_id: 102,
name: "level3 category"
parentId: 101,
idPath: "0-100-101-102"
}
Note with idPath, parentId is not necessary anymore. It's for you to understand the structure easier.
Once you need to find all subcategories of category 100, simply do the query:
db.collection("category").find({_id: /^0-100-/}, function(err, doc) {
// whatever you want to do
})
With category stored in a separate collection, in your product you'll need to reference them by _id, just like when we use RDBMS. For example:
{
... // other fields of product
categories: [100, 101, 102, ...]
}
Now if you want to find all products in a certain category:
db.collection("category").find({_id: new RegExp("/^" + idPath + "-/"}, function(err, categories) {
var cateIds = _.pluck(categories, "_id"); // I'm using underscore to pluck category ids
db.collection("product").find({categories: { $in: cateIds }}, function(err, products) {
// products are here
}
})
Fortunately, category collection is usually very small, with only hundreds of records inside (or thousands). And it doesn't varies a lot. So you can always store a live copy of categories inside memory, and it can be constructed as nested objects like:
[{
id: 100,
name: "level 1 category",
... // other fields
subcategories: [{
id: 101,
... // other fields
subcategories: [...]
}, {
id: 103,
... // other fields
subcategories: [...]
},
...]
}, {
// another top1 category
}, ...]
You may want to refresh this copy every several hours, so:
setTimeout(3600000, function() {
// refresh your memory copy of categories.
});
That's all I get in mind right now. Hope it helps.
EDIT:
to provide int ID for each user, $inc and findAndModify is very useful. you may have a idSeed collection:
{
_id: ...,
seedValue: 1,
forCollection: "user"
}
When you want to get an unique ID:
db.collection("idSeed").findAndModify({forCollection: "user"}, {}, {$inc: {seedValue: 1}}, {}, function(err, doc) {
var newId = doc.seedValue;
});
The findAndModify is an atomic operator provided by mongodb. It will guarantee thread safety. and the find and modify actually happens in a "transaction".
2nd question is in my answer already.
query subsets of properties is described with mongodb Manual. NodeJS API is almost the same. Read the document of projection parameter.
update subsets is also supported by $set of mongodb operator.