I am having a hard time wrapping my head around associations with sailsjs.
I have 2 models
Services
attributes: {
status: {
defaultsTo: 'inactive'
},
userId:{
model: 'users',
via: 'id',
},
},
Users
attributes: {
email: {
type: 'string',
required: true,
unique: true
},
password: {
type: 'string'
}
},
So, a service is tied to a user (matching the id of the user).
I used to do a call like http://localhost:1337/Services?userId=userId
Now I would like to transition to associations using the above model attributes.
This works by calling the ID of the service just fine (it includes the users data as well), however if all i have is the user, how could I get the service
Doing the same call (http://localhost:1337/Services?userId=userId) returns and empty object.
Am I forced to actually have a one-to-one or one-to-many association? I don't understand why I can no longer use the userId field (stored in the DB) to do queries once I start using associations. I guess I am looking for the best of both worlds here.
EDIT:
Let me try make this more clear. Before trying to do associations, I could call this URL (using blueprint)
http://localhost:1337/Services?userId=userId
The Services model used to look like this
attributes: {
status: {
defaultsTo: 'inactive'
},
userId:{
type: 'string',
required: true,
},
},
Then when a user is created, a service for that user is created with the userId matching the ID in the Users table.
Now I would like to implement associations using the above model scheme.
However, because (my best guess) the userId field of the service is mapped to the Users model, I am unable to search for a Server using the userId field that is stored.
I hope that makes sense? In another words, tryin to call
http://localhost:1337/Services?userId=userId
returns nothing when using associations but does return a value when I don't use associations
Related
database noob here using MongoDB, in my program, I have users, and the core of my program are these roadmaps that I display. So, each user can create roadmaps, save others roadmaps, blah blah... Each user has a field named savedRoadmaps and createdRoadmaps which should store the roadmaps. My question is, should I just store the roadmap _ids in the savedRoadmap and createdRoadmaps field or the entire roadmap?
I am asking this because it feels like saving just the _id of the roadmaps can save storage, but it might not come in handy when I have to fetch the data of the user first, then fetch the roadmap using the roadmap ID in the user's savedRoadmap/createdRoadmap field, versus just fetching the user and the savedRoadmap field will already have the roadmap in there.
And btw, is there any sweet and brief database design read out there, please direct me to some if you know any!
For a user, I want it to have a name, email, password, description ofcourse, and also savedRoadmaps and createdRoadmaps. A user can create unlimited roadmaps and also save as much as he or she wants. For a roadmap, I want it to have a name, category, time_completion, author, date, and a roadmap object which will contain the actual json string that I will use d3 to display. Here's my User and Roadmap Schema right now:
const RoadmapSchema = new Schema({
author: {
type: String,
require: false
},
name: {
type: String,
require: true
},
category: {
type: String,
require: true
},
time_completion: {
type: Number,
require: true
},
date: {
type: Date,
default: Date.now
},
roadmap: {
type: "object",
require: true
}
});
and User Schema:
const UserSchema = new Schema({
name: {
type: String,
required: true
},
email: {
type: String,
required: true
},
password: {
type: String,
required: true
},
date: {
type: Date,
default: Date.now
},
savedRoadmap: {
type: "object",
default: []
},
createdRoadmap: {
type: "object",
default: []
}
});
My question is, inside of the savedRoadmap and createdRoadmap fields of the User schema, should I include just the _id of a roadmap, or should I include the entire json string which represents the roadmap?
There are 3 different data-modeling techniques you can use to design your roadmaps system based on the cardinality of the relationship between users and roadmaps.
In general you need to de-normalize your data model based on the queries that are expected from your application:
One to Few: Embed the N side if the cardinality is one-to-few and there is no need to access the embedded object outside the context of the parent object
One to Many: Use an array of references to the N-side objects if the cardinality is one-to-many or if the N-side objects should stand alone for any reasons
One-to-Squillions: Use a reference to the One-side in the N-side objects if the cardinality is one-to-squillions
And btw, is there any sweet and brief database design read out there,
please direct me to some if you know any!
Rules of Thumb for MongoDB Schema Design: Part 1
I recently started working with Sails and mongo.
I use Sails blueprints to generate part of my api.
The problem is, that the request body I send is being saved to the mongo collection, regardless of the fields defined in the model.
So for example, let's say I have the following Event model:
module.exports = {
attributes: {
title: {
type: 'string',
required: true
},
}
}
When I Send a POST request to the /event/ endpoint with the following params:
{"title":"Some Event", "random":"string"}
The saved mongo document contains also the "random":"string" value, even though it's not part of the model.
I've tried to come up with some common method to remove non-model attributes before creation for all models, but the possible solutions seemed not right and dirty.
Am I missing something?
Any help would be appreciated!
You can use schema option in your model. Just add it to model declaration and that's it.
// api/models/Model.js
module.exports = {
schema: true,
attributes: {
title: {
type: 'string',
required: true
}
}
};
I am trying to pull an extra attribute for a model from a different table.
I have been trying with associations but it seems wrong to create an extra model and associate that to my original model.
This is my model Company.js
module.exports = {
schema: true,
autoCreatedAt: false,
autoUpdatedAt: false,
autoPK: false,
attributes: {
name: {
type: 'string'
},
url: {
type: 'string'
},
summary: {
type: 'text'
}
}
};
I have another table in MySQL with two columns, crunchbase_url and company_id, I would like to pull the crunchbase_url into the Company model, what would be the best way to do it without migrating the DB (not an option unfortunately).
Thanks,
Well, turns out that the documentation is fine and all works like a charm by simply creating another model and using one to many association with joined with via.
However, there is a bug that threw me off:
When defaultLimit is set to -1, the find action return an empty list if there are associations.
I have two models
countries - from mysql server
Country = {
tableName: 'countries',
connection: 'someMysqlServer',
schema: true,
migrate: 'safe',
autoCreatedAt: false,
autoUpdatedAt: false,
attributes: {
country_id: {
type: 'integer',
primaryKey: true,
autoIncrement: true
},
....
}
};
User = {
connection: 'somePostgresqlServer',
attributes: {
id: {
type: 'integer',
primaryKey: true,
autoIncrement: true
},
country_id: {
model: 'country'
},
$> User.findOneById(1).populate('country_id').exec(console.log)
and get error
sails> Error (E_UNKNOWN) :: Encountered an unexpected error
: Unable to determine primary key for collection `countries` because an error was encountered acquiring the collection definition:
[TypeError: Cannot read property 'definition' of undefined]
at _getPK (/projects/foturist-server/node_modules/sails-postgresql/lib/adapter.js:923:13)
at StrategyPlanner.__FIND__.Cursor.$getPK (/projects/foturist-server/node_modules/sails-postgresql/lib/adapter.js:504:20)
.....
Details: Error: Unable to determine primary key for collection `countries` because an error was encountered acquiring the collection definition:
[TypeError: Cannot read property 'definition' of undefined]
Why country association uses with postgre-connection ?
Well, since the two models are on different database connections, you're not going to be able to do an actual SQL join. I would think what you'd need is a
User.find({id: 1}).exec(function(user) {
var theUser = user;
Country.find(user.country_id)
.exec(function(country) {
theUser.country = country;
return theUser;
}); });
I'm not sure what specific needs you're trying to address, but since a lookup table of countries is unlikely to frequently change, and is in an entirely different data store, I would suggest caching this data in something like Redis or Memcache. Then on your User find callback you can fetch the country by id from your cache store. This will be much faster unless you expect this data to change on a regular basis. You could write a service that does a lazy lookup in your other database and serves from the cache then on, or cache them all up front when your app launches.
I'm having a hard time trying to figure out if sails/waterline even does this.
(so an adequate answer would simply be if this is possible or not, I have been reading docs, looking through github issues and looking through code, but still not sure)
I have a one to one association setup where an 'account' has a 'contact'
I'm trying to create a contact within sails blueprints (so basically just using the create() method)
account =
{ name: 'Corp'
contact:{
firstName: 'Bob',
lastName: 'Jones'
}
}
so should Account.create(account).exec() create the account and the associated contact? Because I'm getting the following error
TypeError: Cannot convert null to object
My model is setup like so
account.js
module.exports = {
migrate: 'safe',
tableName: 'accounts',
autoPK: false,
attributes: {
id: {
type: 'INTEGER',
primaryKey: true,
autoIncrement: true
},
contactId: 'INTEGER',
name: {type: 'STRING', maxLength: 100},
contact: {
model: 'contact',
columnName:'contactId'
}
}
};
I'm using sails 10.0-rc8 / waterline 10.0-rc15
Creating an associated instance at the same time as its parent (aka "nested create") should work, but it's tricky to get things just right when you're dealing with a legacy database. In your case, the contactId attribute declaration is probably causing the issue, since Waterline expects the foreign key field to be implicit, not explicit. Try removing:
contactId: 'INTEGER',
entirely and see where that gets you.
After some research I found out that as of version 0.10.0-rc15 of waterline you can NOT have a customized foreign keys. In the above model if I change the "contactId" column to just "contact" (basically make it look exactly like it does in the docs. Then it works.
I made the following bug report
https://github.com/balderdashy/waterline/issues/529