use serde_json::{self, Map, Value}; // 1.0.38

fn main() {
    let all_type = b"
    {
       \"number\": 123,
       \"string\": \"abcdefg\",
       \"boolean\": true
    }";
    let string_only = b"
    {
       \"string1\": \"abcdefg\",
       \"string2\": \"abcdefg\",
       \"string3\": \"abcdefg\"
    }";

    let all: Value = serde_json::from_slice(all_type).unwrap();
    let string: Value = serde_json::from_slice(string_only).unwrap();
    let flag1 = is_data_valid(&all);
    let flag2 = is_data_valid(&string);
    println!("{}", flag1);
    println!("{}", flag2);
}

fn is_data_valid(val: &serde_json::Value) -> bool {
    match val.as_object() {
        Some(map) => {
            for key in map.keys() {
                if !is_data_valid(&map[key]) {
                    return false;
                }
            }
        },
        None => {
            match val.as_str() {
                Some(str_val) => true,
                None => false,
            };
        },
    }
    true
}