如何检查快照在Firebase中是否包含特定值？

Question

When I run this code I get an error that says this:

Terminating app due to uncaught exception 'InvalidPathValidation', reason: '(hasChild:) Must be a non-empty string and not contain '.' '#' '$' '[' or ']''

My problem is how do I check if my snapshot contains the value user.email?

self.databaseRef.child("Test").child("xxx").observeSingleEvent(of: .value, with: { (snapshot) in

                    if snapshot.hasChild((user!.email)!){
                        print("yess")
                    }else{
                        print("Not in db")
                    }


                })

Answer 1

You specify your problem in your text. An email always contains a dot '.'. That is not allowed in the key . You check if the key contains the email, but that is not allowed. Structure your database like this:

"email": theemail

This way your key is "email" and your value is theemail . In the value , every string is allowed.

self.databaseRef.child("Test").child("xxx").observeSingleEvent(of: .value, with: { (snapshot) in
    let values = snapshot.value as? NSDictionary
    let email = values?["email"] as? String ?? "No email found"
    // OR
    if let email = values?["email"] as? String{
    //email (above declared variable) holds the value (the real email)
    }else{
    //no email
    }
    if email == (user!.email)!{

    }else{
    }
})

Answer 2

Let me know if this works. It checks to see if the email field actually exists. I think you are getting the error because of the way you're checking for the actual user's email.

self.databaseRef.child("Test").child("xxx").observeSingleEvent(of: .value, with: { (snapshot) in

    if snapshot.hasChild("email"){

        print("yess")

    }else{

        print("Not in db")
    }
})

hasChild returns true if the specified child path has (non-null) data.