Loopback : How to create embedded document or create object type

Here is your Contact model and if you want embed another model called as Address inside it then you need to put relations as embedsOne.
Please note that if you are using mongodb then embeds document will be part of parent document which mean all child documents will not be part of different collections which are linked, rather they will all be part of single parent doc.

“relations”: {
“address”: {
“type”: “embedsOne”,
“model”: “Address”,
“property”: “address”,
“options”: {
“validate”: true,
“forceId”: false
}

Now Contacts.json would look like this

{
“name”: “Contact”,
“base”: “PersistedModel”,
“idInjection”: true,
“options”: {
“validateUpsert”: true
},
“properties”: {
“id”: {
“type”: “string”,
“id”: true,
“defaultFn”: “uuid”
},
“name”: {
“type”: “string”,
“required”: true
},
“phone”: {
“type”: “string”,
“required”: true
},
“email”: {
“type”: “string”
},
“relationship”: {
“type”: “string”
}
},
“validations”: [],
“relations”: {
“address”: {
“type”: “embedsOne”,
“model”: “Address”,
“property”: “address”,
“options”: {
“validate”: true,
“forceId”: false
}
}
},
“acls”: [],
“methods”: {}
}

Please note that default id creator or sub document is “defaultFn”: “uuid” which will add id.