I am currently learning how to use the lookup queries for joins but not getting the expected output
Schema 1
State
{
state_name: { type: String, required: true },
country_name: { type: String, required: true }
}
Schema 2
User
{
name: { type: String },
state: { type: Schema.Types.ObjectId, ref: 'State', required: true },
createdAt: { type: Date, default: Date.now }
}
Query I tried
db.User.aggregate([
{ $match: { _id: ObjectId(b1b1b1) } },
{
$lookup: {
localField: 'state',
from: 'state',
foreignField: '_id',
as: 'user_info'
}
},
]).then(console.log)
Getting user_info as an empty array while I do have both documents like this
State
{
_id: a1a1a1,//ObjectId
state_name: "UP",
country_name: "India"
}
User
{
_id:b1b1b1,//ObjectId
name: Test,
state: a1a1a1,//ObjectId
createdAt:"random date"
}
Output:
[{
_id:b1b1b1,//ObjectId
name: Test,
state: a1a1a1,
createdAt:"random date",
userInfo:[]
}]
