db.py

# Simple DataBase 
#Practice Database comprehension with basic queries

#DataBase Table
users = [
    {
        "id": 1 ,
        "name": "David Makarena" , 
        "email": "david@mail.com",
        "city": "New York"
    } , 
    {
        "id": 2 ,
        "name": "Alice maina" ,
        "email": "alice@mail.com" , 
        "city": "new york" , 
    } , 
    {
        "id": 3 , 
        "name": "Paul  Omondi" , 
        "email": "paul@mail.com" , 
        "city": "nairobi"
    }
    ]


def get_users(database = users ):
    return [ len(database) , database]


def get_user_id( user_id , database = users ): #All users
    for user in database:
        if user["id"] == user_id:
            return user
        else:
            continue
    return 


def get_user( query , database = users ): #Custom user
    found = []
    try:   
        process_argument = query.split("=")
        key_argument = process_argument[0].strip()
        key_value = process_argument[1].strip()
    except Exception as e:
        return[ 0 , f"Error occured. probably because an invalid operator was used.\n{e}" ]
    for user in database:
        if user[key_argument] ==  key_value.lower():
            found.append( user )
        else:
            continue

    num_found = len(found)
    if num_found >= 1 : #If it has appended at least one item / user
        return [ num_found , found]
    else: #If it is  0 ( It has no user ) 
        return [ 0 ,"No results found for your query"] # 0 indicates "No results"
    

def delete_all_users(database = users):
    database.clear()
    return "Database successfully wiped out"



def delete_user( query , database = users):
    to_delete = []
    try:  
        process_argument = query.split("=")
        key_argument = process_argument[0].strip()
        key_value = process_argument[1].strip()
    except Exception as e:
        return[ 0 , f"Error occured. probably because an invalid operator was used.\n{e}" ]
    for user in database:
        if user[key_argument].lower() ==  key_value.lower():
            to_delete.append( user["name"] )
            database.remove( user )
        else:
            continue

    if len(to_delete) >= 1: #If we have at least one user to delete
        return[ len(to_delete) , to_delete ] #Number of users to delete , and their names    
    else:
        return [ 0 , "No user matches that query" ]
    


def add_user( database = users , name = None , email = None , city= None , id = None ):
    user = {}
    user_id = len(database) + 1
    user["id"] = user_id
    if name:
        user["name"] = name
    if email:
        user["email"] = email
    if city:
        user["city"] = city
    else:
        return "No data to add"
    database.append( user )
    print("New user successfully added to the database")
    for key , value in user.items():
        print(f"{key} = {value}")
     




    
#Start the app
while True:
    choices ="""
    1.Get all users
    2.Get custom user
    3.Delete all users
    4.Delete custom user
    5.Add user
    6.Quit
    """
    query_example = "name = david"
    print(choices)
    db_input = input(":")
    while db_input not in [ "1","2","3","4","5","6"]:
        print("Inavlid choice,\nPlease select between:")
        print(choices)
        db_input = input(":")

    if db_input == "1": #Get all users
        db_users = get_users()
        num_db_users = db_users[0]
        all_users = db_users[1]
        if num_db_users >= 1:
            print(f"{num_db_users} results found")
            print(all_users)
        else:
            print(f"Database has got {num_db_users} users")

    elif db_input == "2": #Get custom user
        fetch_query = input(f"Enter query to fetch user\neg: {query_example}\n:")
        found_results = get_user( fetch_query )
        num_users = found_results[0]
        found_users = found_results[1]
        print(f"{num_users} Results found")
        print(f"{found_users}")

    elif db_input == "3": #Delete all users
        deleted = delete_all_users()
        print(deleted)
    
    elif db_input == "4": #Delete custom user
        delete_query = input(f"Enter query to delete user\neg: {query_example}\n:")
        deleted = delete_user( delete_query )
        num_deleted = deleted[0]
        list_deleted = deleted[1]
        print(f"{num_deleted} deleted")
        print(f"{list_deleted}")
    
    elif db_input == "5": #Add user
        print("Non Negotiable. the user must have a name , email , and a city")
        name = input("Enter a name: ")
        email = input("Enter email: ")
        city = input("Enter city: ")
        add_user( name= name , email= email , city= city )

    elif db_input == "6":
        print("Program Ended")
        break