Unable to store a python class object in postgres database

Question

I have a class defined like below

class StatementStatus:
    def __init__(self, id, statement, call, intent, score):
        self.id = callback_id
        self.statement = statement
        self.entities = entities
        self.intent = intent
        self.score = score

    def getIntent(self):
        return self.intent

    def getScore(self):
        return self.score

    def addIntent(self, intent_val):
        self.intent.append(intent_val)

Now I want to store an instance of this class into postgres database.This file is hosted in a django server and I am unable to use django migrations due to some issues in the server.So I need to do it manually.

Below is my django model

class StoreState(models.Model):
    context_name = models.CharField(null=True,max_length=100)
    state = models.BinaryField(null=True)

Here I want to store the StatementStatus instance in a field called state.

Similarly my postgres table structure looks like below

    Column    |          Type          | Modifiers 
--------------+------------------------+-----------
 id           | integer                | 
 context_name | character varying(100) | 
 state        | bytea                  |

But it doesn't store any entry into the table when I do an operation like below

try:
    conv = StoreState.objects.create(
    context_name = callback_id,
    state=s
    )
except Exception as e:
    print("unable to save update", e)

But it doesn't store anything into the table.I get the below error.

('unable to save update', TypeError("can't escape instance to binary",))

What am I doing wrong?

your state is not a binary object. it is just an instance object — Harun ERGUL
– Harun ERGUL, Commented Jul 21, 2018 at 16:19
I think you should create a StatementStatus table and use ForeingKey in your Storestate — Harun ERGUL
– Harun ERGUL, Commented Jul 21, 2018 at 16:27

Harun ERGUL · Accepted Answer · 2018-07-21 16:32:26Z

1

If you want to save your object in your database then use pickle.

import pickle
state = pickle.dump(state) #your state object will be converted to binary

try:
    conv = StoreState.objects.create(
    context_name = callback_id,
    state=s
      )
except Exception as e:
    print("unable to save update", e)

answered Jul 21, 2018 at 16:32

Harun ERGUL

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