Incorrect data saving
You have a trailing comma:

```python

pth.deck_original = bliat,
pth.deck_current = bliat,
``` Oh, my God, this is my mistake)))
Thanks you!!! somehow i had the exact same mistake. Thank god this issue exist :)

I apologize in advance for my English.

 I will describe the problem in a few steps:

1. Creating a model for storing a deck of cards:
```
db = pw.MySQLDatabase(database=db, user=user, password=password, host=host, port=port)`

class PTH(pw.Model):`
    deck_original = pw.TextField(null=True)
    deck_current = pw.TextField(null=True)
    cards_left = pw.TextField(null=True)

    class Meta:
        database = db
```

2. Create object:
```
new_deck: list = generate_deck()
pth = PTH.create(deck_original=str(new_deck),
                            deck_current=str(new_deck),
                            cards_left=str([]))
pth.save()
print(type(new_deck), new_deck)
# <class 'str'> [[13, 'K', 'd', 'Kd', 'K♦'], [3, '3', 'd', '3d', '3♦'], [14, 'A', ...
```

3. And then strange things happen:
```
pth = PTH.get_or_none(PTH.id == pth_id)

new_deck: list = generate_deck()
print('where does the error occur?-1', type(new_deck), new_deck)
# where does the error occur?-1 <class 'list'> [[2, '2', 's', '2s', '2♠'], [8, '8', 's', '8s', '8♠'], [6, '6', ...

print('where does the error occur?-2', type(pth.deck_original), pth.deck_original)
# where does the error occur?-2 <class 'str'> [[13, 'K', 'd', 'Kd', 'K♦'], [3, '3', 'd', '3d', '3♦'], [14, 'A', ...

bliat = str(new_deck)
print('where does the error occur?-3', type(bliat), bliat)
# where does the error occur?-3 <class 'str'> [[2, '2', 's', '2s', '2♠'], [8, '8', ...

pth.deck_original = bliat,
pth.deck_current = bliat,
pth.cards_left = str([])
pth.save()

print('where does the error occur?-4', type(pth.deck_original), pth.deck_original)
# where does the error occur?-4 <class 'tuple'> ("[[2, '2', 's', '2s', '2♠'], [8, '8', 's', '8s', '8♠'], [6, '6', ...
```

Where does the tuple come from?
If I set the bliat variable to  'abcd' (str), the result will be the same.
```
# where does the error occur?-4 <class 'tuple'> ('abcd',)
```

Update:
 If you apply this approach:
```
pth.__data__['deck_original'] = new_deck
# where does the error occur?-4 <class 'tuple'> ([[12, 'Q', 'd', 'Qd', 'Q♦'], [11, 'J', 'c', 'Jc', 'J♣'], [2, '2', ...
```
A list is inserted into the tuple.