006 a database app

use shelve 

import sys,shelve

width=77

def store_person(db):
    """

    Query user for data and store it in the shelf object
    """

    pid=input('Enter unique ID number:')
    if pid in db:
        print('The id exist')
        print_person(db[pid])
        lookup_main(db,pid)
    else:
        db[pid]=input_person()

def lookup_person(db):
    """

    Query user for ID and desired field. and fetch the corresponding
    data from the shelf object
    """
    if len(db.keys())==0:
        print('The database is empty! Please store some data.')
        print('You can try store command.')
        return
    
    while True:
        pid=input('Enter ID number:')
        if pid in db:
            lookup_person_attr(db,pid)
            lookup_main(db,pid)
            return
        print('No this key,Please try again')

def lookup_person_attr(db,pid):
    """

    look up a person attributes by pid
    """
    while True:
        cmd=enter_lookup_attr_cmd()
        if cmd=='?':
            print_attr_help()
        else:
            fields=cmd.split(',')
            if len(fields)==1:
                if fields[0]=='all':
                    print_person(db[pid])
                    return
                
            message=[]  
            for field in fields:
                if field in db[pid]:
                    message.append(print_person_info(db[pid],field))
                else:
                    message.append('No '+field+' attribute')
            beauti_print('Person '+pid+'\'s Information',*message)
            return
        
def modify_person(dp,pid):
    """

    modify a person
    """
    person=dp[pid]
    print_person(person)
    while True:
        cmd=enter_modify_attr_cmd()
        if cmd=='name' or cmd=='age' or cmd=='phone':
            input_person_info(person,cmd)
            break
        elif cmd=='all':
            input_person()
            break
        elif cmd=='?':
            print_attr_help()
        else:
            cmds=cmd.split(",")
            for cmd in cmds:
                input_person_info(person,cmd)
            break
    dp[pid]=person
    print_person(person)
    
def input_person():
    """

    accept user input in a person object
    """
    person={}
    input_person_info(person,'name')
    input_person_info(person,'age')
    input_person_info(person,'phone')
    return person
 
def print_person(p):
    """

    print a person information
    """
    message=[]
    message.append(print_person_info(p,'name'))
    message.append(print_person_info(p,'age'))
    message.append(print_person_info(p,'phone'))
    beauti_print('Person Information',*message)

def input_person_info(p,field):
    p[field]=input('Enter '+field+':')

def print_person_info(p,field):
    return field.capitalize()+': '+p[field]

def del_person(db):
    """

    delete user for ID
    """
    pid=input('Enter ID number:')

    message=[]
    if pid in db:
        del db[pid]
        message.append('Delete success')
    else:
        message.append('No this id!')
    beauti_print('About Delete',*message)
    
def print_attr_help():
    message=[]
    message.append('You can try enter name,age,phone')
    message.append('all      : Prints person all information')
    message.append('?(h)     : Prints this message')
    beauti_print('About Person',*message,flag='=')
    
def print_lookup_help():
    message=[]
    message.append('del(d)   : Delete information about a person by ID number')
    message.append('modify(m): Modify information about a person by ID number')
    message.append('back(b)  : Back to upper list')
    message.append('?(h)     : Prints this message')
    beauti_print('The available commands are',*message,flag='+')
    
def print_help():
    message=[]
    message.append('store(s) : Store information about a person')
    message.append('del(d)   : Delete information about a person by ID number')
    message.append('lookup(l): Looks up a person from ID number')
    message.append('quit(q)  : Save changes and exit')
    message.append('?(h)     : Prints this message')
    beauti_print('The available commands are',*message)
    
def beauti_print(head,*message,flag='*'):
    flag=flag
    if len(flag)>1:
        flag='*'
        
    mess_format=flag+'   '+'%-'+str(width-5)+'s'+flag
    
    left_width=(width-len(head)-2)//2
    right_width=width-len(head)-left_width-2
    print(flag*left_width,head,flag*right_width)
    
    for mess in message:
        print(mess_format % mess)
        
    print(flag*width)

def enter_modify_attr_cmd():
    return base_command('What would you like to modify(? for help):')
def enter_lookup_attr_cmd():
    return base_command('What would you like to know(? for help):')
def enter_lookup_cmd():
    return base_command('what would you like to do about this person(? for help):')
def enter_command():
    return base_command('Enter command(? for help):')

def base_command(message):
    while True:
        cmd=input(message)
        cmd=cmd.strip().lower()
        if cmd!='':
            return cmd

def lookup_main(db,pid):
    while True:
        cmd=enter_lookup_cmd()
        if cmd=='del' or cmd=='d':
            del db[pid]
            print('Delete success!')
            break
        elif cmd=='modify' or cmd=='m':
            modify_person(db,pid)
            break
        elif cmd=='back' or cmd=='b':
            break
        elif cmd=='?' or cmd=='h':
            print_lookup_help()
        
def top_main(db):
    try:
        while True:
            cmd=enter_command()
            if cmd=='store' or cmd=='s':
                store_person(db)
            elif cmd=='lookup' or cmd=='l':
                lookup_person(db)
            elif cmd=='del' or cmd=='d':
                del_person(db)
            elif cmd=='?' or cmd=='h':
                print_help()
            elif cmd=='quit' or cmd=='q':
                return
    finally:
        db.close()
        
def main():
    database=shelve.open(r'E:/tunie/usePython/003oop/database.dat')
    top_main(database)

if __name__=='__main__':
    main()