How to get firebaseData into class/Struct and perform query operation

Firebase Realtime db Json

In my code:

1. contain("University_1") is any way to get character search so i can get university_1 data only
2. I need class/Struct to store all [data] down below

Code:

let ref = Database.database().reference()
ref.child("chat").child("Student_2-University_1").observeSingleEvent(of: .value, with: { (snapshot) in
    for child in (snapshot.children.allObjects as! [DataSnapshot]) {
        if (child.key.contains("user2")){
            print(child.value(forKey: "university_id"))
            // print(child)
        }
    }
})

my struct look like

struct ChatModel {
    
    let lastMessage : LastMesage
    let user1 : StudentData
    let user2 : UniversityData    
    
    struct LastMesage{
        
        let lastMsg : String
        let sendBy: String
        let time: Int
        
    }
    struct StudentData {
        let student_id, student_name: String
    }
    struct UniversityData {
        let university_id, university_name: String
    }
}