Joining two models in loopback using include filter

Question

I have two models Purchase and Products, and productId is common for both.

I need to find the productDetails from product model for a purchaseId.

So I have c

Answer 1

Assuming Product and Purchase models defined as follows:

product.json

{
  "name": "Product",
  "base": "PersistedModel",
  "idInjection": true,
  "properties": {
    "productDesc": {
      "type": "string",
      "required": false
    }
  },
  "validations": [],
  "relations": {
    "purchases": {
      "type": "hasMany",
      "model": "Purchase",
      "foreignKey": "productId"
    }
  },
  "acls": [],
  "methods": {}
}

purchase.json

{
  "name": "Purchase",
  "base": "PersistedModel",
  "idInjection": true,
  "properties": {},
  "validations": [],
  "relations": {
    "product": {
      "type": "belongsTo",
      "model": "Product",
      "foreignKey": "productId"
    }
  },
  "acls": [],
  "methods": {}
}

I have adjusted your query like this:

let product = await Purchase.find({
      include: {
        relation: 'product',
        scope: {
          fields: ['productDesc']
        }
      },
      where: {
        id: 1
      }
    })

Note: ES6 and ES7 used, but it can be easily rewriten to ES5

You have to use toJSON to convert the returned model instance with related items into a plain JSON object.

I'm not sure, why are you creating a new endpoint though. The ones provided by loopback should be sufficient.

e.g.

GET /Purchases/{id}/product

or

GET /Purchases/{id}

with filter

{ "include": [ "product"]}