Sails.js Same Model many to many association - node.js

Sails.js .10 rc8
I've completely run out of ideas for this
I have a model called User and I want to associate it in a collection to other users like a friends list. Like a many-to-many association
//User.js
friends: {
collection: 'user',
via: 'friends'
}
but when I run
.populate('friends')
it doesn't populate anything. Any ideas?


I find that the best way to implement this is actually adding a reference to the id.
Check this User model:
module.exports = {
attributes: {
name: {
type: 'string',
required: true,
minLength: 2
},
email: {
type: 'email',
required: true,
unique: true
},
friends: {
collection: 'user',
via: 'id'
}
}
};
Now, if you run sails console you can test the following commands:
User.create({name:'test',email:'test#test.com'}).exec(console.log);
It returns:
{ name: 'test',
email: 'test#test.com',
createdAt: '2016-12-01T22:06:19.723Z',
updatedAt: '2016-12-01T22:06:19.723Z',
id: 1 }
You created your first user. Lets create some other ones:
User.create({name:'test2',email:'test2#test.com'}).exec(console.log);
Resulting in:
{ name: 'test2',
email: 'test2#test.com',
createdAt: '2016-12-01T22:06:40.808Z',
updatedAt: '2016-12-01T22:06:40.808Z',
id: 2 }
Let's see what we have so far:
User.find().populate('friends').exec(console.log);
[ { friends: [],
name: 'test',
email: 'test#test.com',
createdAt: '2016-12-01T22:06:19.723Z',
updatedAt: '2016-12-01T22:06:19.723Z',
id: 1 },
{ friends: [],
name: 'test2',
email: 'test2#test.com',
createdAt: '2016-12-01T22:06:40.808Z',
updatedAt: '2016-12-01T22:06:40.808Z',
id: 2 } ]
Now, let's create a user with a friend, using the reference to the first user. Notice that I just pass a single id, not an array:
User.create({name:'test3',email:'test3#test.com', friends:1}).exec(console.log);
Now, the result is this one. Notice that "friends" does not appear. This is by design.
{ name: 'test3',
email: 'test3#test.com',
createdAt: '2016-12-01T22:07:34.988Z',
updatedAt: '2016-12-01T22:07:34.994Z',
id: 3 }
Let's do a find with populate to see the current status:
User.find().populate('friends').exec(console.log);
Now we see that the third user has friends. The others have an empty array.
[ { friends: [],
name: 'test',
email: 'test#test.com',
createdAt: '2016-12-01T22:06:19.723Z',
updatedAt: '2016-12-01T22:06:19.723Z',
id: 1 },
{ friends: [],
name: 'test2',
email: 'test2#test.com',
createdAt: '2016-12-01T22:06:40.808Z',
updatedAt: '2016-12-01T22:06:40.808Z',
id: 2 },
{ friends:
[ { name: 'test',
email: 'test#test.com',
createdAt: '2016-12-01T22:06:19.723Z',
updatedAt: '2016-12-01T22:06:19.723Z',
id: 1 } ],
name: 'test3',
email: 'test3#test.com',
createdAt: '2016-12-01T22:07:34.988Z',
updatedAt: '2016-12-01T22:07:34.994Z',
id: 3 } ]
Let's create a fourth one, this time with two friends:
User.create({name:'test4',email:'test4#test.com', friends:[1,2]}).exec(console.log);
Resulting in (again, no friends property):
{ name: 'test4',
email: 'test4#test.com',
createdAt: '2016-12-01T22:07:50.539Z',
updatedAt: '2016-12-01T22:07:50.542Z',
id: 4 }
This time, we passed an array of ids to friends. Let's see the current status:
User.find().populate('friends').exec(console.log);
[ { friends: [],
name: 'test',
email: 'test#test.com',
createdAt: '2016-12-01T22:06:19.723Z',
updatedAt: '2016-12-01T22:06:19.723Z',
id: 1 },
{ friends: [],
name: 'test2',
email: 'test2#test.com',
createdAt: '2016-12-01T22:06:40.808Z',
updatedAt: '2016-12-01T22:06:40.808Z',
id: 2 },
{ friends:
[ { name: 'test',
email: 'test#test.com',
createdAt: '2016-12-01T22:06:19.723Z',
updatedAt: '2016-12-01T22:06:19.723Z',
id: 1 } ],
name: 'test3',
email: 'test3#test.com',
createdAt: '2016-12-01T22:07:34.988Z',
updatedAt: '2016-12-01T22:07:34.994Z',
id: 3 },
{ friends:
[ { name: 'test',
email: 'test#test.com',
createdAt: '2016-12-01T22:06:19.723Z',
updatedAt: '2016-12-01T22:06:19.723Z',
id: 1 },
{ name: 'test2',
email: 'test2#test.com',
createdAt: '2016-12-01T22:06:40.808Z',
updatedAt: '2016-12-01T22:06:40.808Z',
id: 2 } ],
name: 'test4',
email: 'test4#test.com',
createdAt: '2016-12-01T22:07:50.539Z',
updatedAt: '2016-12-01T22:07:50.542Z',
id: 4 } ]
Now, how do you add a friend to an existing user? It's somehow odd: you have to first find the user, then use the add function on the resulting model, and then, save it. In my day to day code, I have a helper function that does just that. So, here is the example:
User.findOne(1).populate('friends').exec(function(err,u){ u.friends.add(3);u.save(function(err){ if(err) console.error(err);});});
Now in the console we see no results.
Let's check the User content now:
User.find().populate('friends').exec(console.log);
[ { friends:
[ { name: 'test3',
email: 'test3#test.com',
createdAt: '2016-12-01T22:07:34.988Z',
updatedAt: '2016-12-01T22:07:34.994Z',
id: 3 } ],
name: 'test',
email: 'test#test.com',
createdAt: '2016-12-01T22:06:19.723Z',
updatedAt: '2016-12-01T22:09:41.410Z',
id: 1 },
{ friends: [],
name: 'test2',
email: 'test2#test.com',
createdAt: '2016-12-01T22:06:40.808Z',
updatedAt: '2016-12-01T22:06:40.808Z',
id: 2 },
{ friends:
[ { name: 'test',
email: 'test#test.com',
createdAt: '2016-12-01T22:06:19.723Z',
updatedAt: '2016-12-01T22:09:41.410Z',
id: 1 } ],
name: 'test3',
email: 'test3#test.com',
createdAt: '2016-12-01T22:07:34.988Z',
updatedAt: '2016-12-01T22:07:34.994Z',
id: 3 },
{ friends:
[ { name: 'test',
email: 'test#test.com',
createdAt: '2016-12-01T22:06:19.723Z',
updatedAt: '2016-12-01T22:09:41.410Z',
id: 1 },
{ name: 'test2',
email: 'test2#test.com',
createdAt: '2016-12-01T22:06:40.808Z',
updatedAt: '2016-12-01T22:06:40.808Z',
id: 2 } ],
name: 'test4',
email: 'test4#test.com',
createdAt: '2016-12-01T22:07:50.539Z',
updatedAt: '2016-12-01T22:07:50.542Z',
id: 4 } ]
With this method, you can even add the same user to the friends collection!
User.findOne(1).populate('friends').exec(function(err,u){ u.friends.add(1);u.save(function(err){ if(err) console.error(err);});});
Have fun!


Your models should look like this...
//User.js
friends: {
collection: 'friend',
via: 'user'
}
//Friend.js
user: {
model: 'user'
via: 'friends'
}
Also sails 10 rc8 is old. You should be on sails 10.5


You should use .populate('friends') instead of .populate(friends)


As it turns out, when you have a many to many association in waterline you have to declare one of the models as dominant. Since they are the same model, neither is dominated. While a join table is created, there is no way to populate it.

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How to pass the entire data in databese to an array in node js (using mongoose)

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const login = await Signupdetails.find(req.body);
login =
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{
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login =
{
PersonalInformation: {
firstName: 'aravind',
lastName: 'john',
phoneNumber: 9736363777,
DOB: 1999-07-08T18:30:00.000Z
},
Address: {
street: 'pillai',
city: 'Chennai',
pincode: 89997,
state: 'kerala',
country: 'India'
},
password: 'social',
_id: 607804f65c166c32144ae227,
email: 'hari#gmail.com',
userName: 'hari',
__v: 0
}
On the other hand, if you want login to be a list, you have to access:
login[0].userName

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[
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image: 'https://image.jpg',
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price: 809,
createdAt: 2020-12-04T17:34:16.869Z,
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price: 809,
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I am unable to solve this issue (and looking to avoid loop update one by one), please hep me out here.
I have a fambio document (which has its own FamilyModel) which gets created after user gives his below information:
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{ _id: 1234, name: 'Jenny', lname: 'doe', relation: 'mother' },
{ _id: 2345, name: 'Jawn', lname: 'doe', relation: 'father' },
{ _id: 3456, name: 'Jane', lname: 'doe', relation: 'sister' },
{ _id: 4567, name: 'Daisy', lname: 'wick', relation: 'pupper' }
]
}
}
});
Thank you everyone!! Hope this helps someone who may face this problem in future.

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