save and recover Storage as string

[lucas]

hello one and all,

i'd like to save and recover Storage instances to a text blob field in a database.  converting to the string is not hard to store it in the field.  recovering it back to a Storage instance is other issue, especially when they're embedded Storage objects in the main Storage object.  i've tried from a script file not under a web2py application as:

#!/usr/bin/env python3

# -*- coding: utf-8 -*-

from sys import path, argv

path.append('/opt/web2py_apps/web2py/')

from gluon import *

from gluon.storage import Storage

if 1:

    ss = Storage(s='main')

    ss.happy = 'yes happy'

    #ss.status = Storage(s1="1status1", s2="2status2")

    print("1:::", ss, type(ss))

    ss = repr(ss)

    print("2:::", ss, type(ss))

    #xglobal, xlocal = globals(), { }

    #eval(ss, xglobal, xlocal)

    ss = eval(ss)

    print("3:::", ss, type(ss))

exit()

with output:

1::: <Storage {'s': 'main', 'happy': 'yes happy'}> <class 'gluon.storage.Storage'>

2::: <Storage {'s': 'main', 'happy': 'yes happy'}> <class 'str'>

Traceback (most recent call last):

  File "./web2py_Storage.py", line 17, in <module>

    ss = eval(ss)

  File "<string>", line 1

    <Storage {'s': 'main', 'happy': 'yes happy'}>

    ^

SyntaxError: invalid syntax

any ideas how to make this work smoothly?  thank you in advance, lucas

[Dave S]

When you convert the storage to string (via the repr() call), don't use the same name.

/dps

 

[lucas]

i'm sorry that doesn't make sense to me.  nonetheless, i tried it with different variable names, as:

if 1:

    ss = Storage(s='main')

    ss.happy = 'yes happy'

    print("1:::", ss, type(ss))

    s1 = repr(ss)

    print("2:::", s1, type(s1))

    s2 = eval(s1)

    print("3:::", s2, type(s2))

and i still got the same error:

1::: <Storage {'s': 'main', 'happy': 'yes happy'}> <class 'gluon.storage.Storage'>

2::: <Storage {'s': 'main', 'happy': 'yes happy'}> <class 'str'>

Traceback (most recent call last):

  File "./web2py_Storage.py", line 17, in <module>

    s2 = eval(s1)

  File "<string>", line 1

    <Storage {'s': 'main', 'happy': 'yes happy'}>

    ^

SyntaxError: invalid syntax

there are so many convertors like to and from json, wouldn't it make sense to and from string for storage?  thank you again, lucas

[Dave S]

On Sunday, April 25, 2021 at 12:52:24 PM UTC-7 lucas wrote:

i'm sorry that doesn't make sense to me.  nonetheless, i tried it with different variable names, as:

My thought was that using the same name was getting into type problems,. 

if 1:

    ss = Storage(s='main')

    ss.happy = 'yes happy'

    print("1:::", ss, type(ss))

    s1 = repr(ss)

    print("2:::", s1, type(s1))

    s2 = eval(s1)

    print("3:::", s2, type(s2))

and i still got the same error:

1::: <Storage {'s': 'main', 'happy': 'yes happy'}> <class 'gluon.storage.Storage'>

2::: <Storage {'s': 'main', 'happy': 'yes happy'}> <class 'str'>

Traceback (most recent call last):

  File "./web2py_Storage.py", line 17, in <module>

    s2 = eval(s1)

  File "<string>", line 1

    <Storage {'s': 'main', 'happy': 'yes happy'}>

    ^

SyntaxError: invalid syntax

there are so many convertors like to and from json, wouldn't it make sense to and from string for storage?  thank you again, lucas

Storage is a special version of dictionary (er, dict), and I don't recognize eval() as a way to initialize a dictionary.   Storage is also pretty simple as a child of dict; gluon/storage.py isn't many lines, and Storage isn't the only class defined there.

This does work:

s1 = "<Storage {'s': 'main', 'happy': 'yes happy'}>"

s2 = Storage()

for sub in s1.replace("<Storage {'",'').replace("'}>",'').split(','):

    key, val = sub.replace("'", "").split(':')

    key = key.strip().rstrip()

    val = val.strip().rstrip()

    s2[key] = val

print(s1, type(s1))

print(s2, type(s2))

Most of the mess in the code comes from de-formatting s1

[lucas]

yes, your method works.

changing the __repr__ line under gluon/storage.py to "__repr__ = lambda self: 'Storage(%s)' % dict.__repr__(self)" will also allow eval(s1) to create the proper and filled Storage instance, or without changing storage.py:

if 1:

    ss = Storage(s='main')

    ss.happy = 'yes happy'

    #ss.status = Storage(s1="1status1", s2="2status2")

    print("1:::", ss, type(ss))

    s1 = repr(ss)

    print("2:::", s1, type(s1))

    s2 = 'Storage('+s1[9:-1]+')'

    print('"%s"' % s2)

    s2 = eval(s2)

    print("3:::", s2, type(s2))

    print(s2.happy)

exit()

where we replace the "<Storage " with "Storage(" at the beginning and ">" with ")" at the end and eval does the rest.

thank you for your help.  i think __repr__ should be updated to my suggestion above so its easier to convert to and from string for easier db storage of python data.  lucas