Firebase实时数据库：4级嵌套上的orderByChild（）。equalTo（）

Question

I'm trying to run a firebase realtime database query to filter data based on value nested at 4th level from root. Below is the data structure and my query is:

let ordersSnapshot = await admin.database().ref(`orders`).orderByChild(`info/infoStatus`)
            .equalTo("In Process")
            .once('value');

But this query is returning no data. I have enabled indexing and there is no warning for it. I have also changed my query to .orderByChild('infoStatus') as well but no result.

If I set my ref one level below ie admin.database().ref('orders/userId1').orderByChild('info/infoStatus').equalTo("In Process") then it gets the result successfully. But in my scenario I don't have the user id which I can use in orderByChild .

Is this the limitation of realtime database query ie I need to update my data structure or is there any error in my query ?

Orders Node:

{
    "userId1": {
        "orderId1": {
            "info": {
                "infoStatus": "In Process"
            }
        },
        "orderId2": {
            "info": {
                "infoStatus": "Complete"
            }
        }
    },
    "userId2": {
        "orderId1": {
            "info": {
                "infoStatus": "In Process"
            }
        }
    },
    "userId3": {
        "orderId1": {
            "info": {
                "infoStatus": "In Process"
            }
        }
    }


}

Answer 1

The property that you order/filter on must be at a fixed path under each child. That means that in your current data structure, you can't filter on orders across all users, only on a specific user.

The typical solution is to flatten the data, storing the orders in a flat list, and adding a lookup list of order IDs to each user if that's still needed. Something like:

users: {
    "userId1": {
        "orderId1": true,
        "orderId2": true
    },
    "userId2": {
        "orderId3": true
    }
    "userId3": {
        "orderId4": true
    }
}
orders: {
    "orderId1": {
        "info": {
            "infoStatus": "In Process"
        }
    },
    "orderId2": {
        "info": {
            "infoStatus": "Complete"
        }
    },
    "orderId3": {
        "info": {
            "infoStatus": "In Process"
        }
    },
    "orderId4": {
        "info": {
            "infoStatus": "In Process"
        }
    }
}

Also see: Firebase Query Double Nested